Content:

NH – Natural Hazards

NH1.1 – Recent innovations and advances in flood modeling, assessment and risk management (Including levees and other flood defences)

EGU21-14646 | vPICO presentations | NH1.1 | Highlight

US fluvial, pluvial and coastal flood hazard under current and future climates

Paul Bates, Niall Quinn, Christopher Sampson, Andrew Smith, Oliver Wing, James Savage, Gaia Olcese, Jeison Sosa, and Jeff Neal

This talk reports a new and significantly enhanced analysis of US flood hazard at 30m spatial resolution.  For the first time we consider pluvial, fluvial and coastal flood hazards within the same framework and provide projections for both current (rather than historic average) conditions and for future time periods centred on 2035 and 2050 under the RCP4.5 emissions pathway.  Validation against high quality local models and the entire catalogue of FEMA 1% annual probability flood maps yielded Critical Success Index values in the range 0.69-0.82.  Significant improvements over a previous pluvial/fluvial model version are shown for high frequency events and coastal zones, along with minor improvements in areas where model performance was already good.  The result is the first comprehensive and consistent national scale analysis of flood hazard for the conterminous US for both current and future conditions.  Even though we consider a stabilization emissions scenario and a near future time horizon we project clear patterns of changing flood hazard (3σ changes in 100yr inundated area of -3.8 to +16% at 1° scale), that are significant when considered as a proportion of the land area where human use is possible or in terms of the currently protected land area where the standard of flood defence protection may become compromised by this time.

How to cite: Bates, P., Quinn, N., Sampson, C., Smith, A., Wing, O., Savage, J., Olcese, G., Sosa, J., and Neal, J.: US fluvial, pluvial and coastal flood hazard under current and future climates, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14646, https://doi.org/10.5194/egusphere-egu21-14646, 2021.

EGU21-1199 | vPICO presentations | NH1.1

Clustering model responses in the frequency space for improved flood risk analysis

Anna E. Sikorska-Senoner

Hydrologic models are employed in the flood risk studies to simulate time series of model responses to given inputs. These simulated time series of pseudo-observations can be next statistically analysed and in this way they can extend existing observed records. Simulations of hydrologic models are however associated with modelling uncertainty, often represented through a simulation ensemble with multiple parameter sets. The need of using multiple parameter sets to represent uncertainty is linked however with increased computational costs that may become prohibitive for long-time series and many input scenarios to be analysed. Due to the non-linear input-output relationship in the hydrologic model, a pre-selection of parameter sets is challenging.

This work presents a clustering approach as a tool to learn about the model hydrologic responses in the flood frequency space from the training dataset. Based on this learning process, representative parameter sets are selected that can be directly used in other model applications to derive prediction intervals at much lower computational costs. The study is supported with sensitivity analysis to the number of clusters. Based on results from a small catchment in Switzerland and 10’000 years of streamflow pseudo-observations, it has been found that grouping the full simulation ensemble with 1000 members into 3 to 10 clusters is already suitable to derive commonly applied prediction intervals (90%, 95% or 98%) in the flood frequency space. The proposed clustering approach can be applied in any flood risk analysis to lower the computational costs linked with the use of a hydrologic model.

How to cite: Sikorska-Senoner, A. E.: Clustering model responses in the frequency space for improved flood risk analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1199, https://doi.org/10.5194/egusphere-egu21-1199, 2021.

EGU21-9838 | vPICO presentations | NH1.1 | Highlight

A conflict between traditional flood measures and maintaining river ecosystems. A case study in river Lærdal, Norway

Ana Juárez, Knut Alfredsen, Morten Stickler, Ana Adeva-Bustos, Sonia Seguín-Garcia, Bendik Hansen, and Rodrigo Suarez

Floods are among the most damaging natural disasters which are likely to increase with the effects of climate change and changes in land use. Therefore, rivers have been the focus of engineering for establishing structural flood mitigation measures. Traditional flood infrastructure, such as levees and dredging have threatened floodplains and river ecosystems and during the last decade, sustainable reconciliation of freshwater ecosystems is increasing. However, we still find many areas where these traditional measures are proposed and it is challenging to find tools for evaluations of different measures and quantification of the possible impacts. We propose the use of hydraulic modelling and remote sensing data for evaluation of different flood strategies and quantification of changes in hydraulic parameters in an ecological scale. This is applied in Lærdal River, in Norway, a national salmon river specially recognized by its environment for Atlantic salmon, where the Norwegian Water Resources and Energy Directorate (NVE) has proposed l flood measures that include confinement with walls and dredging in the riverbed. Results show that the constructing a higher wall could avoid dredging in the river bed resulting in a most cost-effective solution. Dredging could improve hydraulic conditions for juvenile salmon if applied as river restoration measure but channelization of the river would have big impacts in the river ecosystem.

How to cite: Juárez, A., Alfredsen, K., Stickler, M., Adeva-Bustos, A., Seguín-Garcia, S., Hansen, B., and Suarez, R.: A conflict between traditional flood measures and maintaining river ecosystems. A case study in river Lærdal, Norway, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9838, https://doi.org/10.5194/egusphere-egu21-9838, 2021.

EGU21-4723 | vPICO presentations | NH1.1

Combination of geomorphic classifiers through Machine Learning-based techniques for flood hazard assessment 

Andrea Magnini, Michele Lombardi, Simone Persiano, Antonio Tirri, Francesco Lo Conti, and Attilio Castellarin

Every year flood events cause worldwide vast economic losses, as well as heavy social and environmental impacts, which have been steadily increasing for the last five decades due to the complex interaction between climate change and anthropogenic pressure (i.e. land-use and land-cover modifications). As a result, the body of literature on flood risk assessment is constantly and rapidly expanding, aiming at developing faster, computationally lighter and more efficient methods relative to the traditional and resource-intensive hydrodynamic numerical models. Recent and reliable fast-processing techniques for flood hazard assessment and mapping consider binary geomorphic classifiers retrieved from the analysis of Digital Elevation Models (DEMs). These procedures (termed herein “DEM-based methods”) produce binary maps distinguishing between floodable and non-floodable areas based on the comparison between the local value of the considered geomorphic classifier and a threshold, which in turn is calibrated against existing flood hazard maps. Previous studies have shown the reliability of DEM-based methods using a single binary classifier, they also highlighted that different classifiers are associated with different performance, depending on the geomorphological, climatic and hydrological characteristics of the study area. The present study maps flood-prone areas and predicts water depth associated with a given non-exceedance probability by combining several geomorphic classifiers and terrain features through regression trees and random forests. We focus on Northern Italy (c.a. 100000 km2, including Po, Adige, Brenta, Bacchiglione and Reno watersheds), and we consider the recently compiled MERIT (Multi-Error Removed Improved-Terrain) DEM, with 3sec-resolution (~90m at the Equator). We select the flood hazard maps provided by (i) the Italian Institute for Environmental Protection and Research (ISPRA), and (ii) the Joint Research Centre (JRC) of the European Commission as reference maps. Our findings (a) confirm the usefulness of machine learning techniques for improving univariate DEM-based flood hazard mapping, (b) enable a discussion on potential and limitations of the approach and (c) suggest promising pathways for further exploring DEM-based approaches for predicting a likely water depth distribution with flood-prone areas. 

How to cite: Magnini, A., Lombardi, M., Persiano, S., Tirri, A., Lo Conti, F., and Castellarin, A.: Combination of geomorphic classifiers through Machine Learning-based techniques for flood hazard assessment , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4723, https://doi.org/10.5194/egusphere-egu21-4723, 2021.

EGU21-10445 | vPICO presentations | NH1.1 | Highlight

Exploring Sentinel-1 and Sentinel-2 diversity for Flood inundation mapping using deep learning

Goutam Konapala and Sujay Kumar

Identification of flood water extent from satellite images has historically relied on either synthetic aperture radar (SAR) or multi-spectral (MS) imagery. But MS sensors may not penetrate cloud cover, whereas SAR is plagued by operational errors such as noise-like speckle challenging their viability to global flood mapping applications. An attractive alternative is to effectively combine MS data and SAR, i.e., two aspects that can be considered complementary with respect to flood mapping tasks. Therefore, in this study, we explore the diverse bands of Sentinel 2 (S2) derived water indices and Sentinel 1 (S1) derived SAR imagery along with their combinations to access their capability in generating accurate flood inundation maps. For this purpose, a fully connected deep convolutional neural network known as U-Net is applied to combinations of S1 and S2 bands to 446 (training: 313, validating: 44, testing: 89) hand labeled flood inundation extents derived from Sen1Floods11 dataset spanning across 11 flood events. The trained U-net was able to achieve a median F1 score of 0.74 when using DEM and S1 bands as input in comparison to 0.63 when using only S1 bands highlighting the active positive role of DEM in mapping floods. Among the, S2 bands, HSV (Hue, Saturation, Value) transformation of Sentinel 2 data has achieved a median F1 score of 0.94 outperforming the commonly used water spectral indices owing to HSV’s transformation’s superior contrast distinguishing abilities. Also, when combined with Sentinel 1 SAR imagery too, HSV achieves a median F1 score 0.95 outperforming all the well-established water indices in detecting floods in majority of test images.

How to cite: Konapala, G. and Kumar, S.: Exploring Sentinel-1 and Sentinel-2 diversity for Flood inundation mapping using deep learning, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10445, https://doi.org/10.5194/egusphere-egu21-10445, 2021.

EGU21-4187 | vPICO presentations | NH1.1 | Highlight

Improving assessment of flood inundation of Navsari (India) via open-source data and HEC-RAS model

Azazkhan Ibrahimkhan Pathan, Dr.Prasit Girishbhai Agnihotri, Dr. Dhruvesh Patel, and Dr. Critina Prieto

Flooding seems to be the most widespread and common catastrophe in a tropical country such as India. Efficient rainfall, industrial development, huge population, the effect of the tide, and urban growth are actual reasons for flooding in urban coastal regions. Navsari, the city of Gujarat, located 19 km upstream of the Arabian Sea. The city has experienced a devastating flood on 4rth August 2004. Flash flooding and maximum discharge estimated at the Mahuva gauge station of about 8836 m3/sec were responsible for a disaster that resulted in massive damage to property and lives. A two dimensional (2D) flood simulation model is carried out to assessment of flood inundation in an urban coastal area. HEC-RAS is one of the most popular open-source hydraulic software having 2D capabilities including GIS features. In the present study, the distance between the Mahuva gauge station to the Arabian sea was considered for flood inundation assessment, whereas the SRTM 30 m DEM was used for grid generation for Navsari city. The inflow hydrograph was used as the upstream boundary condition, and normal depth was used as the downstream boundary condition during the 4th August 2004 flood event. The unsteady flow simulation was performed and validated for the year of 2004 flood event. The simulated outcomes show that major areas such as Viraval, Kachiawad, Jalalpore, near Railway station, Kaliawad, Tavdi village, and Near TATA School were flooded with 2-4 m depth. Furthermore, the simulated result demonstrates that, if the discharge exceeds 8836 m3/sec in the area of a floodplain, it may take 11 to 13 hours to make the city inundated. The R2 value for the model is 0.9679, which shows that the observed value is the best match with the simulated value. The research study illustrates the accurate flood inundation assessment in the urban coastal area using open-source 2D HEC-RAS model. The present study described the applicability of open-source data and model in flood inundation assessment. The study will fill the gap of flood assessment through 2D HEC-RAS model worldwide areas, which are situated nearby coastal region, accompanied by the benefits of open-source dataset and model.

How to cite: Pathan, A. I., Agnihotri, Dr. P. G., Patel, Dr. D., and Prieto, Dr. C.: Improving assessment of flood inundation of Navsari (India) via open-source data and HEC-RAS model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4187, https://doi.org/10.5194/egusphere-egu21-4187, 2021.

EGU21-6483 | vPICO presentations | NH1.1

Multi-source flood mapping for rapid impact assessment

Kai Schröter, Max Steinhausen, Fabio Brill, Stefan Lüdtke, Daniel Eggert, Bruno Merz, and Heidi Kreibich

Globally increasing flood losses due to anthropogenic climate change and growing exposure underline the need for effective emergency response and recovery. Knowing the inundation situation and resulting losses during or shortly after a flood is crucial for decision making in emergency response and recovery. With increasing amounts of data available from a growing number and diversity of sensors and data sources, data science methods offer great opportunities for combining data and extracting knowledge about flood processes in near real-time.

The main objective of this research is to develop a rapid and reliable flood depth mapping procedure by integrating information from multiple sensors and data sources. The created flood depth maps serve as input for the prediction of flood impacts. This contribution presents outcomes of a demonstration case using the flood of June 2013 in Dresden (Germany) where satellite remote sensing data, water level observations at the gauge Dresden and Volunteered Geographic Information based on social media images providing information about flooding are combined using statistical and machine learning-based data fusion algorithms. A detailed post-event inundation depth map based on terrestrial survey data and aerial images is available as a reference map and is used for evaluation. First results show that the individual datasets have different strengths and weaknesses. The combination of multiple data sources is able to counteract the weaknesses of single datasets and provide a significantly improved flood map and impact assessment. Our work is conducted within the Digital Earth Project (.

 

How to cite: Schröter, K., Steinhausen, M., Brill, F., Lüdtke, S., Eggert, D., Merz, B., and Kreibich, H.: Multi-source flood mapping for rapid impact assessment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6483, https://doi.org/10.5194/egusphere-egu21-6483, 2021.

EGU21-6049 | vPICO presentations | NH1.1 | Highlight

Safety evaluation of buildings under flood impact

Youtong Rong, Paul Bates, and Jeffrey Neal

The flood caused by a dam-break event generally contains a large amount of energy, and it can be destructive to the downstream buildings and structures. An experiment-validated three-dimensional numerical model was designed to investigate the impact of dam-break flood on structures with different arrangements. The Eulerian two-phase flow model and the smooth particle dynamics method are applied separately to solve the flow motion, and  the deformation characteristics of buildings under the flood impact are evaluated by fluid-structure interaction model. An experiment is constructed to validate the numerical simulation. The results show that the structure suffers a large instantaneous impact pressure when the flood water first contacts the structure, and the value of this pressure can reach 1.5-3.0 times that of the maximum pressure after the first impact, and the maximum total pressure of the upstream building surface is about 1800N. The deformation near the door and windows is obvious, and the maximum deformation can reach 600μm, which further results in the large deformation of the gable and roof on both sides. Moreover, the arrangement of buildings has different blocking effect on flood. The back-row buildings arranged in alignment along the flow direction still has to bear 20% flood impact, and the front row buildings arranged alternately bear 90% high-speed flow impact. The structural damage is evaluated by the material failure criterion, and the weak position of buildings is identified, providing an optimal design of buildings.

How to cite: Rong, Y., Bates, P., and Neal, J.: Safety evaluation of buildings under flood impact, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6049, https://doi.org/10.5194/egusphere-egu21-6049, 2021.

EGU21-121 | vPICO presentations | NH1.1

Assessment of lumped physically-based numerical models of dyke breaching

Vincent Schmitz, Grégoire Wylock, Kamal El Kadi Abderrezzak, Ismail Rifai, Michel Pirotton, Sébastien Erpicum, Pierre Archambeau, and Benjamin Dewals

Failure of fluvial dykes often leads to devastating consequences in the protected areas. Overtopping flow is, by far, the most frequent cause of failure of fluvial dykes. Numerical modeling of the breaching mechanisms and induced flow is crucial to assess the risk and guide emergency plans.

Various types of numerical models have been developed for dam and dyke breach simulations, including 2D and 3D morphodynamic models (e.g., Voltz et al., 2017 ; Dazzi et al., 2019 ; Onda et al., 2019). Nevertheless, simpler models are a valuable complement to the detailed models, since they enable fast multiple model runs to test, e.g. a broad range of possible breach locations or to perform uncertainty analysis. Moreover, unlike statistical formulae, physically-based lumped models are reasonably accurate and remain interesting in terms of process-understanding (Wu, 2013 ; Zhong et al., 2017 ; Yanlong, 2020).

Nonetheless, existing lumped physically-based models were developed and tested mostly in frontal configurations, i.e. for the case of breaching of an embankment dam and not a fluvial dyke. Despite similarities in the processes, the breaching mechanisms involved in the case of fluvial dykes differ due to several factors such as a loss of symmetry and flow momentum parallel to the breach (Rifai et al., 2017). Therefore, there is a need to assess the transfer of existing lumped physically-based models to configurations involving fluvial dyke breaching.

Here, we have developed a modular computational modeling framework, in which we are able to implement various physically-based lumped models of dyke breaching. In this framework, we started with our own implementation of the model presented by Wu (2013) and we incorporated a number of changes to the model. Next, we evaluated the model performance for a number of laboratory and field tests covering both frontal (Frank, 2016; Hassan and Morris, 2008) and fluvial (Rifai et al., 2017; 2018; Kakinuma and Shimizu, 2014) configurations. The modular framework we have developed proves also particularly suitable for testing the sensitivity and uncertainties arising from assumptions in the model structure and parameters.

How to cite: Schmitz, V., Wylock, G., El Kadi Abderrezzak, K., Rifai, I., Pirotton, M., Erpicum, S., Archambeau, P., and Dewals, B.: Assessment of lumped physically-based numerical models of dyke breaching, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-121, https://doi.org/10.5194/egusphere-egu21-121, 2021.

EGU21-679 | vPICO presentations | NH1.1 | Highlight

How do transitions affect the wave overtopping flow locally as well as downstream?

Vera van Bergeijk, Jord Warmink, and Suzanne Hulscher

Wave overtopping on grass-covered dikes results in erosion of the dike cover. Once the dike cover is eroded, the core will be washed away and the dike breaches, leading to flooding of the hinterland. Transitions between grass covers and revetments or geometric transitions are vulnerable for cover erosion and are therefore the most likely locations to initiate dike breach. These transitions affect the overtopping flow and thereby the hydraulic load on the dike cover. For example, bed roughness differences can create additional turbulence and slope changes can result in the formation of a jet that increases the load at the jet impact location. Although it is known that dike cover failure often starts at transitions, the effect of transitions on the hydraulic load remains unknown.

We developed a detailed numerical 2DV model in OpenFOAM for the overtopping flow over the crest and the landward slope of a grass-covered dike. This model is used to study the effects of transitions on the overtopping flow variables including the flow velocity, shear stress, normal stress and pressure. Several types of transitions are studied such as revetment transitions, slope changes and height differences. 

The results show that the shear stress, normal stress and pressure increase significantly at geometric transitions such as the transition from the crest to the slope and at the landward toe. The increase depends on the wave volume and the geometry of the dike such as the steepness and length of the landward slope. Furthermore, the results show that roughness changes at revetment transition on a grass-covered crest has no influence on the maximum shear stress, maximum normal stress and maximum pressure. The flow velocity increases from a rough to a smooth revetment, while the opposite occurs for the transition from a smooth to a rough revetment. The variation in the flow velocity is well described by analytical formulas for the maximum flow velocity along the dike profile. These formulas are also able to describe the variation in flow velocity for a revetment transition on a berm on the landward slope. In this case, the shear stress increases from a smooth to a rough revetment and decreases from a rough to a smooth revetment. This means that a rough revetment can locally reduce the shear stress, however the transitions have no effect on the shear stress downstream.

These model results are used to obtain relations for the increase in the hydraulic variables at transitions. These relations can be used to describe the effect of transitions on the hydraulic load in models for grass cover failure by overtopping waves. Accurate descriptions of the hydraulic load in these models will improve the failure assessment of grass-covered dikes with transitions.

How to cite: van Bergeijk, V., Warmink, J., and Hulscher, S.: How do transitions affect the wave overtopping flow locally as well as downstream?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-679, https://doi.org/10.5194/egusphere-egu21-679, 2021.

EGU21-4338 | vPICO presentations | NH1.1

A transient backward erosion piping model based on laminar flow transport equations

Manuel Wewer, Juan Pablo Aguilar-López, Matthijs Kok, and Thom Bogaard

Backward erosion piping (BEP) has been proven to be one of the main failure mechanisms of water-retaining structures worldwide. Dikes, which are often built on sandy aquifers, are particularly vulnerable to this special type of internal erosion. In this research, we propose a numerical solution that combines a 2D Darcy groundwater solution with Exner’s 1D sediment transport mass conservation equation. The inclusion of criteria for incipient particle motion, as well as the linkage of the bedload transport rate to the pipe progression, enables us to build a stable time-dependent piping model. As an estimate of sediment transport, we tested four different empirical transport equations for laminar flow. The model performance was evaluated based on the results of a real-scale dike failure experiment. Through this, we were able to demonstrate the applicability of existing sediment transport equations to the description of particle motion during piping erosion. The proposed transient piping model not only predicts the pipe progression in time, it also allows for an identification of pore pressure transitions due to the erosion process. The main finding of the study is that from the four different modeling approaches for laminar flow, it is recommended to follow the approach of Yalin et al. (1963, 1979) to simulate backward erosion piping in dikes.

How to cite: Wewer, M., Aguilar-López, J. P., Kok, M., and Bogaard, T.: A transient backward erosion piping model based on laminar flow transport equations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4338, https://doi.org/10.5194/egusphere-egu21-4338, 2021.

EGU21-6541 | vPICO presentations | NH1.1

Future estuarine circulation patterns characterization based on a hydrodynamic models ensemble

Isabel Iglesias, José Luís Pinho, Ana Bio, Paulo Avilez-Valente, Willian Melo, José Vieira, Luísa Bastos, and Fernando Veloso-Gomes

Estuarine regions are strategically important from an environmental, economic, and social point of view. To reduce vulnerability and increase resilience, it is crucial to know their dynamics that usually are poorly understood. Numerical models have proven to be an appropriate tool to improve this knowledge and simulate scenarios for future conditions. However, as the modelling results may be inaccurate, the application of the ensembles technique can be very useful in reducing possible uncertainties. In the EsCo-Ensembles project, this technique is proposed to improve hydrodynamic predictions for two Portuguese estuaries: Douro and Minho.

Two already validated numerical models (openTELEMAC-MASCARET and Delft3D), which have demonstrated their ability to accurately describe estuarine hydrodynamic patterns and water elevation for river flow in normal and extreme conditions, were applied. Several scenarios for climate change effects were defined including river flood peak flows for the 100 and 1000 year return periods and sea level extreme values for RCPs 4.5 and 8.5 in 2100.

The results demonstrated a clear difference between the hydrodynamic behaviour of the two estuaries. Model outcomes for the Minho estuary, which is dominated by the tide and therefore by oceanographic conditions, show a pronounced effect of rising sea levels on estuarine hydrodynamics. Whereas, for the Douro estuary, which is heavily dominated by the river flow, the effect of the sea level rise is hardly noticeable during flood events.

These and further results of this ongoing project are expected to (i) provide a complete hydrodynamic characterization of the two estuaries; (ii) evaluate future trends; (iii) estimate the flood risks associated with extreme events and (iv) demonstrate that the combined use of different models reduces their uncertainty and increases the confidence and consistency of the forecasts.

Acknowledgements: To the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 (FCT and ERDF) and to the project EsCo-Ensembles (PTDC/ECI-EGC/30877/2017, NORTE 2020, Portugal 2020, ERDF and FCT). The authors also want to acknowledge the data provided by EDP, IH and Confederación Hidrográfica Miño-Sil.

How to cite: Iglesias, I., Pinho, J. L., Bio, A., Avilez-Valente, P., Melo, W., Vieira, J., Bastos, L., and Veloso-Gomes, F.: Future estuarine circulation patterns characterization based on a hydrodynamic models ensemble, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6541, https://doi.org/10.5194/egusphere-egu21-6541, 2021.

EGU21-7591 | vPICO presentations | NH1.1

Prediction capabilities of GeoFlood for the delineation of flood-prone areas: the Tiber River case study

Claudia D'Angelo, Paola Passalacqua, Aldo Fiori, and Elena Volpi

Land use and delineation of flood-prone areas require valuable and effective tools, such as flood mapping. Local authorities, in order to prevent and mitigate the effects of flood events, need simplified methodologies for the definition of preliminary flooded areas at a large scale. In this work, we focus on the workflow GeoFlood, which can rapidly convert real-time and forecasted river flow conditions into flooding maps. It is built upon two methodologies, GeoNet and the HAND model, making use only of high-resolution DTMs to define the geomorphological and hydraulic information necessary for flood inundation mapping, thus allowing for large-scale simulations at a reasonable economical and computational cost. GeoFlood potential is tested over the mid-lower portion of the river Tiber (Italy), investigating the conditions under which it is able to reproduce successful inundation extent, considering a 200-year return period scenario. Results are compared to authority maps obtained through standard detailed hydrodynamic approaches. In order to analyze the influence of the main parameters involved, such as DTM resolution, channel segmentation length, and roughness coefficient, a sensitivity analysis is performed. GeoFlood proved to produce efficient and robust results, obtaining a slight over-estimation comparable to that provided by standard costly methods. It is a valid and relatively inexpensive framework for inundation mapping over large scales, considering all the uncertainties involved in any mapping procedure. Also, it can be useful for a preliminary delineation of regions where the investigation based on detailed hydrodynamic models is required.

How to cite: D'Angelo, C., Passalacqua, P., Fiori, A., and Volpi, E.: Prediction capabilities of GeoFlood for the delineation of flood-prone areas: the Tiber River case study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7591, https://doi.org/10.5194/egusphere-egu21-7591, 2021.

EGU21-9118 | vPICO presentations | NH1.1

Design of offline reservoirs for flood mitigation by using a structure-based risk framework

Stefano Cipollini, Aldo Fiori, and Elena Volpi

In this work, we present a general framework for design and risk assessment of hydraulic structures for water control. The framework relies on a “structure-based approach”, accounting for both the statistical behavior of the hydrological load acting on the river system and the hydraulic response of the structure to the environmental load. This approach allows for the reduction of a multivariate and complex statistical problem to a univariate one, focusing on the damage. The framework is applied to an offline detention basin for flood mitigation based on a general, yet simplified routing model. Furthermore, a real-world case study application is presented, with the specific aim of discussing the role of the design parameters and their effect on the probability distribution of damage. Results show the robustness and the effectiveness of the approach for applications to real cases and provide design guidance for practitioners.

How to cite: Cipollini, S., Fiori, A., and Volpi, E.: Design of offline reservoirs for flood mitigation by using a structure-based risk framework, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9118, https://doi.org/10.5194/egusphere-egu21-9118, 2021.

EGU21-11038 | vPICO presentations | NH1.1

A multilayer soil approach for seepage process analysis in earthen levees

Bianca Bonaccorsi, Tommaso Moramarco, Leonardo Valerio Noto, and Silvia Barbetta

Earthen levees protect flood-prone areas during severe flood events. In most cases, however, flooding is the result of the collapse of the embankments due to the seepage through and under the levee body. The description of the seepage line is difficult mainly because of the uncertainty on the hydraulic parameters, first of all the soil hydraulic conductivity. Barbetta et al. (2017) proposed a practical method for the seepage analysis based on the Marchi’s equation for the estimation of the probability of occurrence of the levee seepage which provides a vulnerability index under the assumption that the groundwater level coincides with the ground. Recently, the method has been tested also considering the groundwater level below the ground pointing out that such a condition has a high impact on the levee vulnerability to seepage. However, it does not consider the interactions between seepage process in the levee body and in the foundation.

In this context, this work proposes a new approach for the analysis of the infiltration line through the body and the foundation, considering a multilayer soil and assuming a different soil hydraulic conductivity for each layer. The new equation is obtained starting from the continuity equation and the flow equation.

The saturation line estimated through the Marchi’s equation and the one derived through the new multilayer model equation are compared. The analysis is first addressed to identify a threshold of the ratio between water head and water table beyond which the Marchi’s equation is no longer applicable. Indeed, the Marchi’s equation is valid when the river water head is lower than the water table. Different values of these two variables are analyzed and a threshold ratio equal to 0.57 is identified.

Furthermore, the levee vulnerability to seepage estimated with the two approaches is compared and the levee is found more vulnerable when the new approach is applied. The results indicate that the difference between the two vulnerability approaches decreases as the distance between the groundwater table and the ground level tends to zero. The proposed approach is an attempt to quantify the seepage probability with more realistic levees characteristics, hydraulic and soil parameters.

 

Barbetta, S., Camici, S., Bertuccioli, P., Palladino, M. R., & Moramarco, T. 2017. Refinement of seepage vulnerability assessment for different flood magnitude in national levee database of Italy. Hydrology Research, 48(3), 763–775. https://doi.org/10.2166/nh.2017.101.

How to cite: Bonaccorsi, B., Moramarco, T., Noto, L. V., and Barbetta, S.: A multilayer soil approach for seepage process analysis in earthen levees, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11038, https://doi.org/10.5194/egusphere-egu21-11038, 2021.

EGU21-15435 | vPICO presentations | NH1.1

Predicting drought-induced cracks in dikes with machine learning algorithms

Shaniel Chotkan, Juan Pablo Aguilar-López, Raymond van der Meij, Phil Vardon, Wouter Jan Klerk, and Juan Carlos Chacon Hurtado

During intense periods of drought, the development of cracks is observed in peat and clay dikes. Asset managers of the dikes increase the inspection frequency in times of drought to be able to monitor these cracks. Significant development of the cracks contributes to the development of different failure mechanisms. In this study, the occurrence of the cracks is predicted at a large spatial scale. An inspection database in which the observations from the last three years are stored is used as the basis. The database contains hundreds of observed cracks including the  location and time in which they were observed. The database was extended with attributes such as the precipitation deficit, the peat width at the surface, the orientation of the dike body, the subsidence of the dike body and the soil stiffness. Decision tree algorithms were then used to classify which circumstances will lead to cracks and which circumstances will not. From the resulting decision trees it was deduced that high precipitation deficits, low soil stiffness and the peat width can be used as the main predictors for the occurrence of cracks. Both subsidence of the foundation and the dike body being orientated to the sunny side are also contributors, although less prominent. Time-independent cracking criteria were then used to classify which regions are prone to cracking. Dikes which are rich in peat with a low stiffness were thus highlighted. The Mathews correlation coefficient was used as performance criteria resulting in a 0.3 value for the obtained tree. Application of a random forest increased the coefficient to 0.8. An important conclusion is that proper monitoring of the peat width, soil stiffness and precipitation may result in better asset management.

How to cite: Chotkan, S., Aguilar-López, J. P., van der Meij, R., Vardon, P., Jan Klerk, W., and Chacon Hurtado, J. C.: Predicting drought-induced cracks in dikes with machine learning algorithms, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15435, https://doi.org/10.5194/egusphere-egu21-15435, 2021.

EGU21-12223 | vPICO presentations | NH1.1

Simulation of a small scale model of dike susceptible to suffusion

Rachel Gelet, Alaa Kodieh, and Didier Marot

EGU21-14904 | vPICO presentations | NH1.1

Proof of Concept with Distributed Temperature Sensing for Crack Detection on Dikes

Leonardo Duarte Campos and Juan Pablo Aguilar López

Cracks occurring on dike surfaces due to droughts, are a big threat for the safety of flood defence infrastructure as they increase infiltration rates and reduce the resistance to mass rotational failure (slope stability). Hence, an effective and sustainable monitoring system for crack detection is of paramount importance given the increase in frequency of drought events. Conventional methods heavily rely on visual inspections by expert observers, drone technologies survey, or destructive techniques such as sampling and trenching. Most of them result sparse qualitative and labor-intensive assessments. In this project, we aim to develop a method which combines two different sensing techniques —distributed temperature sensing (DTS) and conventional video cameras— for detecting the cracks on the dike surface. In contrast to earlier studies using DTS to measure the temperature changes during high water levels in the riverside slope and to detect seepage changes, we will be measuring the superficial moisture content on the riverside and the landside slopes of the dike, and use it as a proxy for crack detection in combination with the camera images and deep learning techniques. It is expected that by including the DTS measurements, the detection of cracks may outperform the actual methods in an economically and more densely manner along several kilometers of dikes in real time.

How to cite: Duarte Campos, L. and Aguilar López, J. P.: Proof of Concept with Distributed Temperature Sensing for Crack Detection on Dikes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14904, https://doi.org/10.5194/egusphere-egu21-14904, 2021.

Floods are natural disasters caused mainly due to heavy or excessive rainfall. They induce massive economic losses in Bangladesh every year. Physically-based flood prediction models have been used over the years where simplified forms of physical laws are used to reduce calculations' complexity. It sometimes leads to oversimplification and inaccuracy in the prediction. Moreover, a physically-based model requires intensive monitoring datasets for calibration, accurate soil properties information, and a heavy computational facility, creating an impediment for quick, economical and precise short-term prediction. Researchers have tried different approaches like empirical data-driven models, especially machine learning-based models, to offer an alternative approach to the physically-based models but focused on developing only one machine learning (ML) technique at a time (i.e., ANN, MLP, etc.). There are many other techniques, algorithms, and models in machine learning (ML) technology that have the potential to be effective and efficient in flood forecasting. In this study, five different machine learning algorithms- exponent back propagation neural network (EBPNN), multilayer perceptron (MLP), support vector regression (SVR), DT Regression (DTR), and extreme gradient boosting (XGBoost) were used to develop total 180 independent models based on a different combination of time lags for input data and lead time in forecast. Models were developed for Someshwari-Kangsa sub-watershed of Bangladesh's North Central hydrological region with 5772 km2 drainage area. It is also a data-scarce region with only three hydrological and hydro-meteorological stations for the whole sub-watershed. This region mostly suffers extreme meteorological events driven flooding. Therefore, satellite-based precipitation, temperature, relative humidity, wind speed data, and observed water level data from the Bangladesh Water Development Board (BWDB) were used as input and response variables.

For comparison, the accuracy of these models was evaluated using different statistical indices - coefficient of determination, mean square error (MSE), mean absolute error (MAE), mean relative error (MRE), explained variance score and normalized centred root mean square error (NCRMSE). Developed models were ranked based on the coefficient of determination (R2) value. All the models performed well with R2 being greater than 0.85 in most cases. Further analysis of the model results showed that most of the models performed well for forecasting 24-hour lead time water level. Models developed using XGBoost algorithm outperformed other models in all metrics. Moreover, each of the algorithms' best-performed models was extended further up to 20 days lead time to generate forecasting horizon. Models demonstrated remarkable consistency in their performance with the coefficient of determination (R2) being greater than 0.70 at 20 days lead-time of forecasting horizon in most cases except the DTR-based model. For 10- and 5-days lead time of forecasting horizon, it was greater than 0.75 and 0.80 respectively, for all the model extended. This study concludes that the machine algorithm-based data-driven model can be a powerful tool for flood forecasting in data-scarce regions with excellent accuracy, quick building and running time, and economic feasibility.

How to cite: Haque, M. H., Sadia, M., and Mustaq, M.: Development of Flood Forecasting System for Someshwari-Kangsa Sub-watershed of Bangladesh-India Using Different Machine Learning Techniques, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15294, https://doi.org/10.5194/egusphere-egu21-15294, 2021.

EGU21-15322 | vPICO presentations | NH1.1

A state-based and optimal path dependant short-term flood planning 

Mengke Ni and Tohid Erfani

Temporary flood protective defences (TFPD) are supplementary to permanent engineering solutions. In a flood event, asset managers are faced with a challenging task of deploying large-scale temporary defences at multiple locations. As the performance of temporary defences is sensitive to various uncertain weather condition factors, it is difficult to fix a single specific deployment plan as the optimal solution. This, moreover, leads to insufficient and/or underused defences on flood-affected locations. This paper describes a state-based (SB) mathematical modelling approach to deal with above challenge by adapting TFPD strategies consistently to short-term future as they unfold. We employ multistage stochastic and scenario tree to identify a set of alternative SB optimal paths for deployment planning. The proposed model is applied to nine flood-affected locations in Carlisle, northwest England. The results indicate that the inclusion of SB path-dependant solution strategy are beneficial for the flood asset manager faced with making short-term deployment planning decisions.

How to cite: Ni, M. and Erfani, T.: A state-based and optimal path dependant short-term flood planning , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15322, https://doi.org/10.5194/egusphere-egu21-15322, 2021.

EGU21-12779 | vPICO presentations | NH1.1 | Highlight

Can soils act as environmental sponges to help reduce flooding?

Joshua Ahmed, Robert E. Thomas, Joshua Johnson, Edward Rollason, Christopher Skinner, and Daniel R. Parsons

Flooding presents a serious socioeconomic challenge to riverine communities across the world, impacting >300 million people each year and causing loss of life, damage to infrastructure, long-term mental and physical health problems, and threatening food security. Across many parts of the globe, including north-west Europe, climate change is projected to increase the magnitude, frequency, and intensity of rainfall events, thus exacerbating future flood risk and increasing the demand for flood alleviation schemes. Historically, flood prevention strategies have focused on constructing hard defences that restrict the overbank flows and aim to convey them downstream. However, as floods become larger and more difficult to predict, the construction of ever-higher defences becomes unfeasible. As such, natural-based solutions are being adopted as a more cost-effective and sustainable approach to managing flood waters through upland attenuation in leaky dams and offline storage in reservoirs in the lowlands. Here we demonstrate the feasibility and efficacy of using agricultural soils as “environmental sponges” to retain moisture and reduce downstream flood peaks in a heavily-managed lowland catchment. We use combined field, laboratory, and modelling approach to quantify how increases in soil organic matter – introduced through cover crops – can increase soil moisture retention at the field scale and perform groundwater and catchment modelling scenarios to assess how these changes can be extrapolated up to the catchment scale and used to forecast changes in downstream flood risk across a suite of future hydro-climatic and soil management scenarios.

How to cite: Ahmed, J., Thomas, R. E., Johnson, J., Rollason, E., Skinner, C., and Parsons, D. R.: Can soils act as environmental sponges to help reduce flooding?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12779, https://doi.org/10.5194/egusphere-egu21-12779, 2021.

EGU21-15210 | vPICO presentations | NH1.1

A (semi-)probabilistic storm surge EWS implementation for the Emilia-Romagna region (Italy)

Luis Germano Biolchi, Silvia Unguendoli, Lidia Bressan, Beatrice Maria Sole Giambastiani, and Andrea Valentini

The low lying and sandy coastal areas of the Emilia-Romagna region are heavily threatened by sea storms, often leading to flooding and coastal erosion events with severe impacts on citizens’ quality of life, damages to the cultural heritage and effects on economic activities (e.g. aquaculture, fisheries, tourism, beach facilities). Climate change projections reinforce the need of strategies and tools to prevent damages and promptly react to extreme events. In this context and in the framework of non-structural mitigation measures, the Hydro-Meteo-Climate Service of Arpae Emilia-Romagna (Arpae-SIMC) developed and operationally manages a Coastal Early Warning System (EWS) for the Emilia-Romagna Region (Northeast Italy).

The EWS was developed during the EU Project FP7-MICORE and it is a state-of-the-art coastal forecasting system that follows a chain of operational numerical models: the meteorological model COSMO, the wave model SWAN-MEDITARE, the ocean model AdriaROMS, and the morphodynamic model XBeach. The latter is currently implemented on a series of cross-shore beach profiles covering eight locations distributed along the Emilia-Romagna shore. Deterministic daily forecasts (72-hours) are generated and Storm Impact Indicators (SIIs) used to assess sea-storm induced coastal risk along the region’s littoral (geo.regione.emilia-romagna.it/schede/ews). 

It is widely known that among the limitations of deterministic approaches, the lack of uncertainty estimation is often problematic as decision-makers might be misled if the only forecast available underestimates (or overestimates) incoming conditions. Hence, following the success of probabilistic forecasting in meteorological applications, storm surge EWSs following ensemble frameworks have been recently developed, allowing for more information available to sustain the decision-making process. Towards the new paradigm change, one of the foreseen outputs of the European Interreg Italy-Croatia CBC Programme project Strategic development of flood management (STREAM) involves the development of a “probabilistic EWS for coastal risk implemented and tested on at least one location along the Emilia-Romagna Coast”. 

The initial implementation of the (semi-)probabilistic framework benefits from the EU ADRION I-STORMS (Integrated Sea Storm Management Strategies) project outcomes, in which wave and sea level multi-model ensembles were developed for the Adriatic Sea giving origin to the Transnational Multi-Model Ensemble (TMES). The TMES was made available as one of the six Integrated Web System (IWS) components, combining five wave and six sea level forecasting systems as means to provide 48-hour forecasts in terms of sea level and wave characteristics (Hs, Tm and Dm). Ensemble mean and standard deviation (SD) are calculated based on different forecasting systems’ results. In the initial approach, four TMES combinations have been tested as XBeach forcing: the TMES mean; the mean minus one SD; the mean plus one SD; the mean plus two SDs. Two months were analyzed together with the already implemented deterministic system for two profiles along the region’s coast.

The methodology followed for the test period will be shown as well as the results. Furthermore, the methodology under development will be also shown as means to enhance the discussion involving storm surge ensemble applications.

How to cite: Germano Biolchi, L., Unguendoli, S., Bressan, L., Giambastiani, B. M. S., and Valentini, A.: A (semi-)probabilistic storm surge EWS implementation for the Emilia-Romagna region (Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15210, https://doi.org/10.5194/egusphere-egu21-15210, 2021.

NH1.3 – Extreme heat events: processes, impacts and adaptation

EGU21-2582 | vPICO presentations | NH1.3

Trends in heat stress over Europe over the 20th century

Joakim Kjellsson, Nils Niebaum, and Robin Pilch Kedzierski

We investigate how European heat waves and their associated heat stress on humans have changed over the 20th century. We find that the heat stress has increased, even in regions where heat waves have not become warmer. As heat stress increases over wide areas of Europe there is also an increase in the total population affected by the heat stress. 

Heat waves pose a serious health risk to humans by reducing our ability to shed heat. We have studied the occurrence and intensity of heat waves as well as a heat stress index based on simplified wet-bulb globe temperature using data from ERA-20C reanalysis 1900-2010. Over the 110 years of data we find an overall warming of the air temperatures and dew point. The 98th percentile of both air temperature has increased by more than 1.5°C over large areas of Europe. 

We find an overall increase in heat wave days per year as well as an increase of air temperature during heat waves over most of Europe. As such, many densely populated areas exhibit increased heat stress during heat waves. For example, the mean heat stress during heat wave days over Paris has increased by one level, from “alert” in 1900-1930 to “caution” in 1980-2010. The fraction of the population exposed to heat waves has increased by 10%/century in central Europe and 25%/century over the Mediterranean. 

We find more heat waves during 1920 - 1950, which may be related to the positive phase of the Atlantic Multidecadal Variation (AMV). This suggests that the heat stress during European heat waves may also be influenced by internal climate variability, and large-ensemble model simulations may be used to disentangle the effects of natural variability and anthropogenic forcing.

How to cite: Kjellsson, J., Niebaum, N., and Pilch Kedzierski, R.: Trends in heat stress over Europe over the 20th century, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2582, https://doi.org/10.5194/egusphere-egu21-2582, 2021.

EGU21-46 | vPICO presentations | NH1.3

Borderless Heat Stress

Chloe Brimicombe, Claudia Di Napoli, Rosalind Cornforth, Florian Pappenberger, Celia Petty, and Hannah Cloke

Heatwaves are increasing in intensity, duration and frequency. One of the impacts of heatwaves is heat stress, which can lead to death and raised morbidity. This project, uses a mixed method approach. Using the ERA5.HEAT reanalysis data of the UTCI – a bio-meteorological heat stress index- and temperature, to study the climatology and trends of heat at a global level and at a regional and country level for African nations. In addition, we review a range of literature from academic papers, international reports and EM-DAT the international disaster database. All of this reveals the extent to which heat risk is communicated. As well as, revealing the growing size of heatwaves. These together provide evidence of whether more preparedness measures are needed.

How to cite: Brimicombe, C., Di Napoli, C., Cornforth, R., Pappenberger, F., Petty, C., and Cloke, H.: Borderless Heat Stress, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-46, https://doi.org/10.5194/egusphere-egu21-46, 2021.

EGU21-9677 | vPICO presentations | NH1.3

Using Machine Learning to investigate Heat Waves and Myocardial Infarctions in Augsburg, Germany

Lennart Marien, Mahyar Valizadeh, Wolfgang zu Castell, Alexandra Schneider, Kathrin Wolf, Diana Rechid, and Laurens Bouwer

Myocardial infarctions (MI) are a major cause of death worldwide. In addition to well-known individual risk factors, studies have shown that temperature extremes, such as encountered during heat waves, lead to increases in MI. The relationship between health impacts and climate is complex, depending on a multitude of climatic, environmental, sociodemographic and behavioral factors. Machine Learning (ML) is a powerful tool for investigating complex and unknown relationships between extreme environmental conditions and their adverse impacts that has already been applied to other climate extremes, such as in the prediction of flood damages. By combining heterogeneous health, climatic, environmental and socio-economic datasets, this study is a first step in developing an ML model for predicting past and future MI risk due to heat waves.

Here, we present first results of our ML approach for modelling heat-related health effects in Augsburg based on the KORA MI and environmental data. The basis of our data-driven approach is the KORA cohort study and the MI Registry in the Augsburg region of Bavaria, Germany, comprising detailed information on MI and underlying health conditions. Additionally, weather and climate data, air pollution data (e.g., PM10, PM2.5, nitrous oxides, and ozone), as well as socio-economic data (household income, education) are used for this study. One of the key challenges is to assemble and integrate heterogeneous data from various sources and prepare them for the appropriate spatial scales. We outline major challenges in combining these data and deriving quantitative models from them.

Moreover, we present initial results based on both regression and classification models, discussing model performance for the period between 2000 and 2015, with a focus on two major heat wave events in Germany during 2003 and 2006. Ultimately, this research may be useful in better understanding heat-related MI risks, supporting possible adaptation options in urban areas and in identifying high-risk groups within society.

How to cite: Marien, L., Valizadeh, M., zu Castell, W., Schneider, A., Wolf, K., Rechid, D., and Bouwer, L.: Using Machine Learning to investigate Heat Waves and Myocardial Infarctions in Augsburg, Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9677, https://doi.org/10.5194/egusphere-egu21-9677, 2021.

EGU21-10365 | vPICO presentations | NH1.3

Can a local weather station be used in place of on-site measurements for heat stress assessment in a sports setting?

Olivia Cahill, Andrew Grundstein, Christian Walker, and Earl Cooper

Across the globe, exposure to environmental heat stress may impose increased health and safety hazards to active populations such as athletes and workers. Monitoring heat stress is a key component of a well-designed heat mitigation policy. Yet, the cost of several hand-held heat stress sensors may pose a financial barrier for use in many circumstances. Numerous areas, however, have existing networks of weather stations that could potentially be incorporated into monitoring heat stress. Currently, the Japanese Ministry of the Environment has set up a network of weather stations across the city to monitor environmental conditions in preparation of the 2021 Tokyo Olympic and Paralympic games. Our research question asks how representative are the values recorded at local weather stations (often located over a natural surface) to playing field conditions with various surfaces and microclimate conditions. In the U.S. the WeatherSTEM network has over 600 stations scattered across the country and measures a suite of variables relevant to heat stress including air temperature, humidity, wind speed, solar radiation and models the wet bulb globe temperature (WBGT) values. This study will compare measurements from a local WeatherSTEM station with on-site measurements taken over three different playing surfaces (grass, synthetic turf, and hardcourt tennis) in a humid subtropical climate in Athens, Georgia. U.S. It will also compare WBGT values computed using different models. Our results may provide insight not only for sports but also for the workplace which take place over various surface types and environments.

How to cite: Cahill, O., Grundstein, A., Walker, C., and Cooper, E.: Can a local weather station be used in place of on-site measurements for heat stress assessment in a sports setting?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10365, https://doi.org/10.5194/egusphere-egu21-10365, 2021.

EGU21-11842 | vPICO presentations | NH1.3 | Highlight

Dynamical and thermodynamical drivers of variability in European summer heat extremes

Laura Suarez-Gutierrez, Chao Li, Wolfgang A. Müller, and Jochem Marotzke

We use the 100-member Max Planck Institute Grand Ensemble (MPI-GE) to disentangle the contributions from colocated dynamic atmospheric conditions and local thermodynamic effects of moisture limitation as drivers of variability in European summer heat extremes. Using a novel extreme event definition, we find that heat extremes with respect to the evolving mean climate increase by 70% under a moderate warming scenario during the twenty-first century. With a multiple regression approach, we find that the dynamical mechanisms representing blocking and anticyclonic conditions are the main driver of variability in extreme European summer temperatures, both in past and future climates. By contrast, local thermodynamic drivers play a secondary role in explaining the total variability in extreme temperatures. We also find that considering both dynamical and thermodynamical sources of variability simultaneously is crucial. Assessing only one type of drivers leads to an overestimation of their effect on extreme temperatures, particularly when considering only thermodynamical drivers. Lastly, we find that although most past and future heat extremes occur under favorable dynamical atmospheric conditions; this occurs 10–40% less frequently over Central Europe in the twenty-first century. By contrast, heat extremes over Central Europe occur 40% more frequently under concurrent extreme moisture limitation in the twenty-first Century. Our findings highlight a new type of neutral-atmosphere, dryness-driven heat extremes, and confirm that the increase in European heat extremes and associated variability increase are dominated by the local thermodynamic effect of moisture limitation.

How to cite: Suarez-Gutierrez, L., Li, C., Müller, W. A., and Marotzke, J.: Dynamical and thermodynamical drivers of variability in European summer heat extremes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11842, https://doi.org/10.5194/egusphere-egu21-11842, 2021.

EGU21-566 | vPICO presentations | NH1.3 | Highlight

Amplified warming of extreme temperatures over tropical land

Michael Byrne

Extreme temperatures have warmed substantially over recent decades and are projected to continue warming in response to future climate change. Warming of extreme temperatures is amplified over land where the impacts on human health, wildfire risk and food production are most severe. Using simulations with climate models, I show that hot days over tropical land warm substantially more than the average day. For example, warming of the hottest 1% of land days is 24% larger than the time-mean warming averaged across models. The climate-change response of extreme temperatures over tropical land is interpreted using a theory based on atmospheric dynamics. According to the theory, warming is amplified for hot land days because those days are dry: I term this the "drier get hotter" mechanism. Changes in near-surface relative humidity further increase tropical land warming , with decreases in land relative humidity particularly important. The theory advances physical understanding of the tropical climate and highlights land-surface dryness as a key factor determining how extreme temperatures will respond to future climate change.

How to cite: Byrne, M.: Amplified warming of extreme temperatures over tropical land, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-566, https://doi.org/10.5194/egusphere-egu21-566, 2021.

EGU21-1587 | vPICO presentations | NH1.3

Projections of tropical heat stress constrained by atmospheric dynamics

Yi Zhang, Isaac Held, and Stephan Fueglistaler

Extreme heat under global warming is a concerning issue for the growing tropical population. However, model projections of extreme temperatures, a widely used metric for extreme heat, are uncertain on regional scales. In addition, humidity also needs to be taken into account in order to estimate the health impact of extreme heat. Here we show that an integrated temperature-humidity metric for the health impact of heat, namely the extreme wet-bulb temperature (TW), is controlled by established atmospheric dynamics and thus can be robustly projected on regional scales. For each 1°C of tropical mean warming, global climate models project extreme TW (the annual maximum of daily-mean or 3-hourly values) to increase roughly uniformly between 20°S and 20°N latitude by about 1°C. This projection is consistent with theoretical expectations based on tropical atmospheric dynamics, and observations over the past 40 years, which gives confidence to the model projection. For a 1.5°C warmer world, the likely (66 per cent confidence interval) increase of regional extreme TW is projected to be 1.33-1.49°C, whereas the uncertainty of projected extreme temperatures is 3.7 times as large. These results suggest that limiting global warming to 1.5°C will prevent most of the tropics from reaching a TW of 35°C, the limit of human adaptation.

How to cite: Zhang, Y., Held, I., and Fueglistaler, S.: Projections of tropical heat stress constrained by atmospheric dynamics, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1587, https://doi.org/10.5194/egusphere-egu21-1587, 2021.

EGU21-12972 | vPICO presentations | NH1.3

Heat Events in the Indian Subcontinent under a warming climate scenario: Detection and its Drivers 

Ritika Kapoor, Carmen Alvarez-Castro, Enrico Scoccimarro, Stefano Materia, and Silvio Gualdi

Rising global temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity.

In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat-related deaths are on a rise, and heat waves can impact various sectors including health, agriculture, ecosystems and the national economy.

Preliminary results show the prevalence of heat events in seven different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months. We consider daily maximum temperatures (Tmax) and the NOAA’s Heat Index (HI), a combination of temperature and relative humidity that gives an insight into the discomfort because of increment in humidity.

We look into various drivers behind the heat events in the seven different clusters, in particular ENSO and the North Atlantic Regimes that have been linked to the generation of heat waves in different parts of India. The preliminary results indicate Nino 3.4 SST anomalies show positive correlation with Tmax anomalies only in the western coast during pre-monsoon season, while in the transitional months positive correlation extends to central and east India. The Tmax composite anomalies for the cold, warm and neutral phases of ENSO show positive anomalies for only warm years and negative anomalies for the cool and neutral years. Heat Index shows similar spatial patterns for correlation analysis and composite anomaly analysis. The Mean Sea Level Pressure (MSLP) composite associated with heat waves (days exceeding 95th percentile=>3 days) show a persistent ridge over the North Atlantic region.

 

How to cite: Kapoor, R., Alvarez-Castro, C., Scoccimarro, E., Materia, S., and Gualdi, S.: Heat Events in the Indian Subcontinent under a warming climate scenario: Detection and its Drivers , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12972, https://doi.org/10.5194/egusphere-egu21-12972, 2021.

EGU21-2596 | vPICO presentations | NH1.3 | Highlight

Future changes in heatwaves over Africa at the convection-permitting scale

Cathryn Birch, Lawrence Jackson, Declan Finney, John Marsham, Rachel Stratton, Simon Tucker, Cath Senior, and Richard Keane

Mean temperatures and their extremes have increased over Africa since the latter half of the 20th century and this trend is projected to continue, with very frequent, intense and often deadly heatwaves likely to occur very regularly over much of Africa by 2100. It is crucial that we understand the scale of the future increases in extremes and the driving mechanisms. We diagnose daily maximum wet bulb temperature heatwaves, which allows for both the impact of temperature and humidity, both critical for human health and survivability. During wet bulb heatwaves, humidity and cloud cover increase, which limits the surface shortwave radiation flux but increases longwave warming. It is found from observations and ERA5 reanalysis that approximately 30% of wet bulb heatwaves over Africa are associated with daily rainfall accumulations of more than 1 mm/day on the first day of the heatwave. The first ever pan-African convection-permitting climate model simulations of present-day and RCP8.5 future climate are utilised to illustrate the projected future change in heatwaves, their drivers and their sensitivity to the representation of convection. Compared to ERA5, the convection-permitting model better represents the frequency and magnitude of present-day wet bulb heatwaves than a version of the model with more traditional parameterised convection. The future change in heatwave frequency, duration and magnitude is also larger in the convective-scale simulation, suggesting CMIP-style models may underestimate the future change in wet bulb heat extremes over Africa. The main reason for the larger future change appears to be the ability of the model to produce larger anomalies relative to its climatology in precipitation, cloud and the surface energy balance.

How to cite: Birch, C., Jackson, L., Finney, D., Marsham, J., Stratton, R., Tucker, S., Senior, C., and Keane, R.: Future changes in heatwaves over Africa at the convection-permitting scale, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2596, https://doi.org/10.5194/egusphere-egu21-2596, 2021.

EGU21-3140 | vPICO presentations | NH1.3

Assessment of the projected temperature extremes over the MENA region from CIMP5 scenario runs 

Athanasios Ntoumos, Panos Hadjinicolaou, George Zittis, and Jos Lelieveld

This study provides an overview of the projected temperature extremes over the MENA region until the end of the 21st century. The main objectives of our analysis are the following: i) analyze the projected changes in temperature extremes using the CMIP5 multi-model ensemble, reveal ii) the warmest model realizations and iii) the “hotspot” locations within MENA with the projected highest temperature extremes. For this purpose, a list of indices of temperature extremes, based on threshold, percentile, heatwave and coldwave characteristics is used, as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). We use daily near-surface air (2-metre) temperature (Tmax and Tmin) to derive the extremes-indices for the period 1980-2100. The data were taken from 18 CMIP5 models combining historical (1980-2005) and scenario runs (2006-2100 under RCP 2.6, RCP4.5 and RCP8.5). Using these datasets, the indices of temperature extremes were derived. The changes of the extremes over the 21st century are analyzed, in space and time, relative to the reference period 1981-2000. Moreover, a model ranking is performed based on the magnitude of the projected changes of the indices and the relation with the model climate sensitivity is explored. A further analysis of model statistics over specific locations/grid points reveals the areas with the projected most intense heat extremes.

How to cite: Ntoumos, A., Hadjinicolaou, P., Zittis, G., and Lelieveld, J.: Assessment of the projected temperature extremes over the MENA region from CIMP5 scenario runs , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3140, https://doi.org/10.5194/egusphere-egu21-3140, 2021.

EGU21-14302 | vPICO presentations | NH1.3

Storylines of plausible past and future climates for the July 2019 European heatwave

Antonio Sánchez Benítez, Thomas Jung, Helge Goessling, Felix Pithan, and Tido Semmler

Under the current global warming trend, heatwaves are becoming more intense, frequent, and longer-lasting; and this trend will continue in the future. In this context, the recent 2019 summer was exceptionally hot in large areas of the Northern Hemisphere, with embedded heatwaves, as for example the June and July 2019 European events, redrawing the temperature record map in western Europe. Large-scale dynamics (associated with blockings or subtropical ridges) play a key role in explaining these-large scale events.

Conceptually, global warming can be split into two different contributions: Dynamic and thermodynamic changes. Whereas dynamic changes remain highly uncertain, some thermodynamic changes can be quantified with higher confidence. We exploit this concept by studying how these recent European heatwaves would have developed in a pre-industrial climate and how it would develop in the future for 1.5, 2 and 4 ºC warmer climates (storyline scenarios). To do so, we employ the spectral nudging technique with AWI-CM (CMIP6 model, a combination of ECHAM6 AGCM + FESOM Sea Ice-Ocean Model). Large-scale dynamics are prescribed by reanalysis data (ERA5). Meanwhile, the model is run for different boundary conditions corresponding to preindustrial and future climates along the SSP370 forcing scenario. This approach can be useful to help understand and communicate what climate change will mean to people’s life and hence facilitate effective decision-making regarding adaptation to climate change, as we are quantifying how recent outstanding events would be modified by our climate action. 

Temperatures during the heatwaves often increase twice as much as global mean temperatures, especially in a future 4 ºC warmer climate. In this future climate, maximum temperatures can locally reach 50ºC in many western Europe countries. Nighttime temperatures would be similar to the daytime temperatures in a preindustrial world. The global warming amplification can be partly explained by a robust soil drying in the future 4 ºC warmer climate (exacerbated due to the June 2019 heatwave) which is transmitted to a robust increase in Bowen ratio. Importantly, by design of our study, this response occurs without any changes in atmospheric circulation.

How to cite: Sánchez Benítez, A., Jung, T., Goessling, H., Pithan, F., and Semmler, T.: Storylines of plausible past and future climates for the July 2019 European heatwave, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14302, https://doi.org/10.5194/egusphere-egu21-14302, 2021.

EGU21-2987 | vPICO presentations | NH1.3

A multi-year drought scenario for western Europe

Claudia Gessner, Erich Fischer, Urs Beyerle, and Reto Knutti

During the last decades, Europe has experienced intense dry and hot spells, which seriously impact socio-economic sectors and the ecosystem by shortages of water in the summer season. The occurrence of two exceptional consecutive dry summers 2018/2019 let a multi-year drought become a conceivable scenario. In order to implement adaptation strategies for such a natural hazard, stakeholders raise the questions, how dry and hot a worst-case drought scenario would turn out and how long it would take to fully recover from those climate anomalies?

We address these concerns through the generation of storylines, describing the driest plausible multi-year droughts over western Europe. By repeatedly resampling the occurrence of precipitation in the climate simulation, using 100-member ensembles, we inhibit rainfall and dehydrate the soils in western Europe. These storylines and a millennial climate control simulation are carried out with CESM1.2 under pre-industrial forcing.

In doing so, local precipitation is reduced by 80% and local soil moisture falls far below the 1st percentile of the climatology. Even compared to the present and future climate scenarios, still, the number of dry days is very rare in our drought storyline, i.e. we describe a hazardous but unlikely scenario. Moreover, these storylines are associated with the hottest spring, summer and fall temperatures, but also the coldest winter temperatures. Starting large ensembles from each summer of the multi-year drought scenario, i.e. under exceptional dry initial soil conditions, we find that summertime hot and dry spells have a twenty-fold chance to occur plus their persistence extents by about 1.5 days. After strong precipitation deficits in the summer months, the precipitation increases again. Nevertheless, the local soil moisture does not fully recover within the next year so that the following spring and summer season may be affected by re-occurring droughts, aggravating the damage through water deficits for the vegetation growth and the economy.

How to cite: Gessner, C., Fischer, E., Beyerle, U., and Knutti, R.: A multi-year drought scenario for western Europe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2987, https://doi.org/10.5194/egusphere-egu21-2987, 2021.

EGU21-7972 | vPICO presentations | NH1.3

Heat stress projections for major European cities from high-resolution regional climate model simulations

Clemens Schwingshackl, Anne Sophie Daloz, Carley Iles, Nina Schuhen, and Jana Sillmann

Cities are hotspots of human heat stress due to their large number of inhabitants and the urban heat island effect leading to amplified temperatures. Exposure to heat stress in urban areas is projected to further increase in the future, mainly due to climate change and expected increases in the number of people living in cities. The impacts of climate change in cities have been investigated in numerous studies, but rarely using climate models due to their coarse spatial resolution compared to the typical areal extent of cities. Recent advances in regional climate modelling now give access to an ensemble of high-resolution simulations for Europe, allowing for much more detailed analyses of small-scale features, such as city climate.

Focusing on Europe, we compare the evolution of several heat stress indicators for 36 major European cities, based on regional climate model simulations from EURO-CORDEX. The applied EURO-CORDEX ensemble (Vautard et al., 2020) has a spatial resolution of 0.11° (~11 km; comparable to the extent of large cities) and contains over 60 ensemble members, allowing thus for robust multi-model analyses of climate change on city levels. We analyze changes in heat stress both relative to the climatological heat stress variability in each city during 1981-2010 using the Heat Wave Magnitude Index daily (HWMId, Russo et al., 2015) and in absolute terms by counting the yearly number of exceedances of impact-relevant thresholds. Relative and absolute heat stress increase throughout Europe but with distinct patterns. Absolute heat stress increases predominantly in Southern Europe, primarily due to the hotter climate in the South. Relative changes are also highest in Southern Europe but exhibit a secondary maximum in Northern Europe, while being lowest in Central Europe. The main reason for this pattern is that day-to-day variability in heat stress indicators during present climate conditions is highest in Central Europe but lower in Southern and Northern Europe. Large Northern European cities, which are all located at the shore, are further influenced by different heat stress evolutions over land and sea surfaces.

As human vulnerability does not only depend on the absolute heat stress but also on what people are adapted to (i.e., the climatological range), the results of this study highlight that cities in all parts of Europe – including in Northern Europe – must prepare for higher heat stress in the future.

 

References:

Russo, S., et al. (2015). Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environmental Research Letters, 10(12). doi:10.1088/1748-9326/10/12/124003

Vautard, R., et al. (2020). Evaluation of the large EURO‐CORDEX regional climate model ensemble. Journal of Geophysical Research: Atmospheres. doi:10.1029/2019jd032344

How to cite: Schwingshackl, C., Daloz, A. S., Iles, C., Schuhen, N., and Sillmann, J.: Heat stress projections for major European cities from high-resolution regional climate model simulations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7972, https://doi.org/10.5194/egusphere-egu21-7972, 2021.

EGU21-9181 | vPICO presentations | NH1.3 | Highlight

Future Projections of Heat Mortality Risk for Major European Cities due to Heat Waves

Alexia Karwat and Christian L. E. Franzke

Over the last few decades heat waves have intensified, become more common, pose severe health risks, especially in densely populated cities, and have led to excess mortality. While the probability of being adversely affected by heat stress has significantly increased over the last few decades, the risk of heat mortality is rarely quantified. This quantification of heat mortality risk is necessary for systematic adaptation measures. Furthermore, heat mortality records are sparse and short, which presents a challenge for assessing heat mortality risk for future climate projections. It is therefore crucial to derive indicators for a systematic heat mortality risk assessment. Here, risk indicators based on temperature and mortality data are developed and applied to major cities in Germany, France and Spain, using regional climate model simulations. These simulations have biases of up to 3°C with respect to observations and, thus, need to be bias-corrected. Bias-corrected daily maximum, minimum and wet-bulb temperatures show increasing trends in future climate projections for most considered cities. Additionally, we derive a relationship of daily maximum temperatures and mortality for producing future projections of heat mortality risk due to extreme temperatures based on low (Representative Concentration Pathway; RCP2.6) and high (RCP8.5) emission scenario future climate projections. Our results illustrate that heat mortality increases by about 0.9%/decade in Germany, 1.7%/decade in France and 7.9%/decade in Spain for RCP8.5 by 2050. The future climate projections also show that wet-bulb temperatures above 30°C will be reached regularly with maxima above 40°C likely by 2050. Our results suggest a significant increase of heat mortality in the future, especially in Spain. On average, our results indicate that the mortality risk trend is almost twice as high in all three countries for the RCP8.5 scenario compared to RCP2.6.

How to cite: Karwat, A. and Franzke, C. L. E.: Future Projections of Heat Mortality Risk for Major European Cities due to Heat Waves, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9181, https://doi.org/10.5194/egusphere-egu21-9181, 2021.

EGU21-5158 | vPICO presentations | NH1.3 | Highlight

An urban climate service to manage heat risks in UK and Chinese cities 

Victoria Ramsey and Claire Scannell

Recent extreme heat events in the UK are likely to become more frequent over the 21st Century and exacerbated in cities due to the urban heat island effect. Due to high population densities and a concentration of assets, urban areas are more vulnerable to climatic extremes with impacts that traverse health, infrastructure, built environment and economic activity. Risks to health, well-being and productivity from high temperatures is one of six priority areas from in UK Climate Change Risk Assessment (2017) where more action is needed to manage risks, prompting local authorities to understand heat risks within their city. 
City based climate services are needed for day-to-day operations in cities, emergency response and to inform urban design and development.  Recent advances in high resolution modelling enable better representation of urban processes and provide greater understanding of extreme events.  By exploiting such advances in underpinning science, the Met Office is generating urban climate services for city stakeholders to plan for and manage heat stress in their city.
The Met Office has been engaging with local authorities and city stakeholders in the UK and China to co-produce a prototype, two tier, urban heat climate service to enhance the resilience of urban environments to extreme heat events.  The prototype is based on a strong requirement from several cities to develop an evidence base of the heat hazard and understand current and future hot spots vulnerable to extremes of heat within the city.  Tier 1 uses observations and high-resolution climate data to provide city specific information of the heat hazard in a graphical factsheet format.  This includes information on future changes in temperature, extreme heat indicators, frequency and duration of heatwave events, and spatial distribution of heat across the city.  Tier 2 involves working closely with city stakeholders to combine the hazard information with data on health, built environment and socio-economics, to provide tailored information on heat exposure and vulnerability.  This will allow users to identify highly vulnerable parts of the city network and neighbourhoods for priority action.  This two-tier service can provide an evidence base to inform urban policy, design and adaptation strategies, and prepare authorities and city stakeholders for future demand on city services. 

How to cite: Ramsey, V. and Scannell, C.: An urban climate service to manage heat risks in UK and Chinese cities , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5158, https://doi.org/10.5194/egusphere-egu21-5158, 2021.

NH1.4 – Nature-based solutions for hydro-meteorological risk reduction

EGU21-1501 | vPICO presentations | NH1.4 | Highlight

Nature-Based solutions for geo-hydrological risk reduction: the Portofino Park (Italy) experience in the H2020 RECONECT project

Francesco Faccini, Andrea Benedettini, Valentina Brodasca, Umberto Bruschini, Riccardo Giammarini, Fabio Luino, Cristiana Mortola, Francesca Neonato, Paolo Noce, Andrea Robbiano, Laura Turconi, and Guido Paliaga

The Horizon 2020 RECONECT - Regenerating ECOsystems with Nature-Based Solutions for hydro-meteorological risk rEduCTion - Project aims to contribute to a European reference framework on NBS by demonstrating, upscaling and spreading large-scale NBSs in natural areas.

The Italian RECONECT demonstrator is set in the Portofino Park, which represents a unique natural and cultural landscape but is severely endangered by geo-hydrological hazards.

The most frequent processes are shallow landslides and flash floods, sea-storm surges, rockfalls and mud-debris flows. Often, several different processes can occur simultaneously during an intense meteorological event, causing a location specific multi-hazard effect.

This research introduces the NBSs interventions designed within the RECONECT Italian case study in two pilot catchments (San Fruttuoso and Paraggi basins), accessed by thousands of tourists throughout the year.

Amongst all possible interventions that can be implemented in the protected area, NBSs are considered to be most suitable due to their minimal impact and the possibilities for integration within the natural environment. The Portofino Park has already been promoting interventions aimed at reducing the impact of geo-hazards within the protected area in response to climate change. As part of the RECONECT project, and in order to achieve sound engineering and technological solutions which can also preserve unique landscapes of natural and cultural heritage, the Park authority is realizing a set of NBSs in San Fruttuoso and Paraggi catchments. The purpose of the design is to demonstrate how NBSs can be integrated into such areas and how to reduce geo-hydrological risk for given climate change scenarios within the framework of an ecosystem based holistic approach for risk reduction.

The main scope of NBSs in San Fruttuoso is to address following basic challenges: stabilizing of rock masses; reduction of geo-hydrologic risks in order to intercept and reduce suspended and solid transport along the streams as well as reducing erosion; forest management focused to improve biodiversity, to remove non-native species and dangerous old specimen (Pine trees), not suitable in a Mediterranean climate, in order to select the climax species (i.e. Quercus ilex); restoration of dry-stone walls with the aim to valorize the terraced landscape as well as stabilizing the slopes.

The reconstruction of terraces and the regeneration of natural and man-made ecosystems will also be implemented within the Paraggi basin. In addition, hydraulic-forestry arrangements on water courses will be undertaken to improve the outflow and decrease solid transport and floating debris. Furthermore, other measures such as riverbed and tributary implementations, maintenance along hiking paths, slope stabilization, and cleaning and removing dead vegetation and dirt will also be undertaken.

The project also includes hydro-meteorological monitoring activities in the selected basins and the periodic checking of NBSs performance indicators. Lastly, remote sensing surveys are used to quantitatively assess the ongoing gemorphogical processes.

In relation to future projections of natural and socio-economic impacts of climate change, NBS represent a relevant mitigation and adaptation strategy for the Portofino case study, which may be upscaled to national and international level.

How to cite: Faccini, F., Benedettini, A., Brodasca, V., Bruschini, U., Giammarini, R., Luino, F., Mortola, C., Neonato, F., Noce, P., Robbiano, A., Turconi, L., and Paliaga, G.: Nature-Based solutions for geo-hydrological risk reduction: the Portofino Park (Italy) experience in the H2020 RECONECT project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1501, https://doi.org/10.5194/egusphere-egu21-1501, 2021.

EGU21-3977 | vPICO presentations | NH1.4 | Highlight

The role of man-made terraces as NBS measure for geo-hydrological risk reduction in the Portofino Park (Italy) - H2020 RECONECT project

Guido Paliaga, Francesco Faccini, Fabio Luino, Laura Turconi, and Zoran Vojinovic

Man-made terraces are widely diffused in hilly-mountainous areas, representing an ancient anthropogenic landscape modification for agricultural purposes. Then, terraces have been involved in several changes through times: socio-economic evolution caused a progressive general abandonment of terraced areas causing land use change and even their obliteration or collapse. In some cases, terraces deeply shaped the landscape and then their maintenance is considered crucial for cultural, aesthetic and even touristic value.

Terraces belong to the soil and water conservation measures as they allow to reduce erosion, improve slope stabilization and retain water runoff; as such they fit perfectly into the Natured-Base Solution definition. The artificial immobilization of debris and stone in terraces may turn in a possible source of geo-hydrological hazard in case of heavy rains, as happened in the Riviera Ligure in the last 20 years; a sequence of events was associated to landslides and flash flood, causing damages and casualties. Then, the proper terraces maintenance and monitoring is crucial for the maintenance of the geomorphological and geotechnical slope stability.

We focused on terraces identification and on the evaluation of debris/stones volume trapped after centuries of human activity in the pilot area of the Portofino Park, which represents a unique natural and cultural landscape that is severely endangered by geo-hydrological hazards. The further step has been the spatial relationships assessment with the exposed elements like buildings, infrastructures and culverted stream, that is the basis of risk assessment and land use planning activities.

The research has been carried out within the framework of the Horizon 2020 RECONECT - Regenerating ECOsystems with Nature-Based Solutions for hydro-meteorological risk rEduCTion; the Italian RECONECT demonstrator is set in the Portofino Park.

Using a detailed Lidar survey, the edges of dry-stone walls were firstly identified, allowing a detailed mapping. Focusing to terrace bases allowed to recognize a possible natural surface through their interpolation along the slope: the difference between the terraced slope profile and the interpolated one allowed a preliminary volume assessment.

Dry-stone wall basis has been detected applying a local upslope curvature routine that is the weighted mean of local curvatures of the directly neighboring upslope contributing cells, controlled with 5 cm orthophoto. In very steep areas terraces stored volume mediumly accounts about 0.35 m3/m2, which agrees with the back analysis estimation of volumes collapsed after recent geo-hydrological events in the Ligurian Riviera.

Stored volume is an essential parameter for prioritizing terraces restoration interventions for risk reduction through NBS techniques. Finally, the survey and analysis outcome may be useful to investigate the recent numerous geo-hydrological events that have been triggered in terraced areas in large sectors of the Mediterranean.

How to cite: Paliaga, G., Faccini, F., Luino, F., Turconi, L., and Vojinovic, Z.: The role of man-made terraces as NBS measure for geo-hydrological risk reduction in the Portofino Park (Italy) - H2020 RECONECT project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3977, https://doi.org/10.5194/egusphere-egu21-3977, 2021.

EGU21-2052 | vPICO presentations | NH1.4

Nature-based sealing of leaky streams - Testing a bio-degradable bentonite mat for preventing infiltration losses in alpine stream

Thomas Zieher, Jan Pfeiffer, Annemarie Polderman, Kent von Maubeuge, Helmut Hochreiter, Christian Ribis, Veronika Lechner, and Daniel Bergmeister

Deep-seated landslides can pose a serious threat to settlement areas and their assets in mountain regions across the world. An important step of a holistic landslide management is the implementation of suitable mitigation measures. However, technical mitigation measures against the impacts of natural hazards often rely on synthetic materials. Progress in materials science and development often makes it possible to replace synthetic components with renewable, bio-degradable materials that provide the same functionality. These alternative, nature-based solutions can simultaneously offer co-benefits such as environmental sustainability, less maintenance efforts and a greater societal acceptance. In this context, an experimental setup was installed in the upslope catchment area of an active deep-seated landslide in Vögelsberg (community of Wattens, Tyrol, Austria). At the chosen location the infiltration losses along the unconsolidated streambed potentially contribute to groundwater recharge, which is considered a main hydrological driver of the landslide. The goal of the experiment was to efficiently seal a 25 m long section of a stream without relying on synthetic materials. To reach this goal, a prototype of a bio-degradable bentonite mat was implemented as an impermeable layer in the subsurface of the leaky stream section. The efficacy of the mat is continuously monitored by several soil moisture probes installed below and above the layer and repeated measurements of subsurface characteristics with the help of electrical resistivity tomography. Furthermore, topographic changes due to erosion or sagging of the embankments are periodically monitored using a terrestrial laser scanner. Currently, the implemented solution must be considered a concept case to help raise awareness for this nature-based alternative to conventional engineering measures based on synthetic materials. If the experiment proves successful, it could be upscaled in the upstream catchment area of the landslide to prevent infiltration along leaky streams in the same way and reduce the hydrological forcing of the landslide.

The present study has been carried out in the OPERANDUM project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776848.

How to cite: Zieher, T., Pfeiffer, J., Polderman, A., von Maubeuge, K., Hochreiter, H., Ribis, C., Lechner, V., and Bergmeister, D.: Nature-based sealing of leaky streams - Testing a bio-degradable bentonite mat for preventing infiltration losses in alpine stream, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2052, https://doi.org/10.5194/egusphere-egu21-2052, 2021.

EGU21-3249 | vPICO presentations | NH1.4

Exploring Perceptions of Natural Water Retention Measures and Their Implementation: A Case Study in Northeastern Italy

Giacomo Bernello, Elena Mondino, and Lucia Bortolini

Heavy rainfall is one of the hydrogeological hazards increasingly connected with climatic changes. Natural Water Retention Measures (NWRMs) implementation represents a chance to build resilient communities and to reduce potential damage. This water management approach has several designs and can be adopted at different scales. However, NWRMs are not widespread, and in some cases they are even ignored by both citizens and public administrations. Understanding how people perceive NWRMs is the first step to promote the implementation of these structures. This study aims at exploring people’s knowledge of NWRMs and their attitudes towards them. We conducted a survey in the Veneto Region (Northeastern Italy) in 2020. Preliminary data exploration shows that the overall knowledge of NWRMs varies depending on the type of retention measure. Respondents’ attitudes towards NWRMs are positive in public areas (e.g. green spaces, parking lots), but are more heterogeneous when it comes to private properties (e.g. houses, private gardens). Further investigations are therefore needed concerning the last point. This study provides a deeper understanding of the dynamics behind water management systems’ implementation to reduce heavy rainfall and flood damage and can inform policymakers dealing with flood risk management.

How to cite: Bernello, G., Mondino, E., and Bortolini, L.: Exploring Perceptions of Natural Water Retention Measures and Their Implementation: A Case Study in Northeastern Italy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3249, https://doi.org/10.5194/egusphere-egu21-3249, 2021.

EGU21-14887 | vPICO presentations | NH1.4

Future salt intrusion climate scenarios: the case of the Po river

Giorgia Verri, Sahameddin Mahmoudi Kurdistani, Nadia Pinardi, Giovanni Coppini, Andrea Valentini, and Dario Conte

A 2-layer Estuary Box Model, named CMCC EBM (Verri et al., 2020), has been devised by the CMCC Foundation to offer a proper representation of the estuarine overturning circulation and mixing processes in a coupled modelling framework with hydrology models and ocean models. The regional to global ocean models reaching the mesoscale cannot solve the estuarine dynamics because they cannot represent the estuary geometry due to their low resolution. Thus, the idea of an estuary box model that gives reasonable values of water volume flux and salinity at the river mouth, which in turn affects the ocean dynamics.

A further development of the model equations (Verri et al. 2021, under revision) considers the estuary length, i.e.  the length of the salt wedge intrusion, as a model unknown which depends on the competition between the riverine freshwater and the salt ocean water.

The physical core of the model consists of two conservation equations for volume flux and salt flux both averaged over the diurnal tidal cycle. Moreover, two non-dimensional equations based on the Buckingham theorem have been conceived to provide the estuary length and the along-estuary eddy diffusivity (Verri et al., under revision) as time-variable parameters instead of assuming they are static as most box models do.

The input fields required by the CMCC EBM are the river runoff at the estuary head and the ocean inflow at the river mouth in terms of both barotropic tidal inflow through the water column and baroclinic inflow at the bottom. The estuary width and depth at the river mouth are the only tunable parameters of the CMCC EBM.

The model capability to estimate the length of the salt wedge intrusion has been tested and validated. The Po di Goro branch of the Po delta system has been selected as case study. It is representative of the river-dominated estuaries in a micro-tidal sea, the so called “salt wedge estuaries”, with a multiannual average of the salt wedge intrusion around 15 km according to the ArpaE monitoring campaigns.

Overall the high statistical performance, the short computation time and the minimal calibration encourage to use the CMCC EBM in coupled mode with mesoscale ocean models to produce more realistic operational forecasts and climate scenarios.

In the framework of the Operandum H2020 project (https://www.operandum-project.eu), the CMCC EBM has been used to provided historical simulations (1981-2010 time window) and mid-term scenarios (2021-2050 time window under RCP 8.5) of both the salt wedge length and the salinity at the Po di Goro mouth. The final aim is to design and develop a site-specific nature-based solution which may address the pressing issue of the salinization of the inland waters. The CMCC EBM results clearly showed a stronger intrusion of saltier ocean water in the middle term. The average, the minimum and the maximum values of salinity at the river mouth provided by the model projections are assumed as reference values to investigate the behaviour of two halophyte species which have been selected to reduce the saline intrusion problem because of their high salinity absorption capacity.

How to cite: Verri, G., Mahmoudi Kurdistani, S., Pinardi, N., Coppini, G., Valentini, A., and Conte, D.: Future salt intrusion climate scenarios: the case of the Po river, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14887, https://doi.org/10.5194/egusphere-egu21-14887, 2021.

EGU21-5801 | vPICO presentations | NH1.4

Barriers and levers for implementing sustainable Nature-Based Solutions in cities

Chloé Duffaut, Nathalie Frascaria-Lacoste, and Pierre-Antoine Versini

Hydro-meteorological risks are increasing and this could be due to global changes. These risks are particularly important in the urban context where most human beings live. Indeed, the impervious surfaces present in cities increase the risk of flooding, for example. Nature-Based Solutions can help to reduce these risks by creating permeable soils or storing water while promoting biodiversity. In this context, it is essential to understand what hinders the development and sustainability of these Nature-based Solutions in the city and what could help to deploy them on a large scale. For this purpose, various professionals working on Nature-Based Solutions in the city in France, were interviewed between 2020 and 2021, both in the academic and operational sectors, or even at the interface between the two: researchers in ecology or hydrology, IUCN (International Union for Conservation of Nature) project manager, project managers at the Regional Biodiversity Agency, director and natural environment manager of a watershed union, agro-economists engineer among others. They were asked what are the barriers and potential opportunities for Nature-Based Solutions implementation and sustainability in city. By analysing their answers, it emerges that the obstacles are more often cultural, political or financial than technical. The potential levers often mentioned are education and awareness-raising at all levels, especially for elected officials and the general public. Regulations such as the PLU (Local Urban Plan) and new funding for more natural spaces in the city also seem to be means of promoting Nature-based Solutions in urban areas. These interviews with diverse professionals directly involved in Nature-Based Solutions in cities allow to give real courses of action to be taken to democratize these Solutions throughout the French territory, or even internationally, and therefore ultimately reduce the risks of hydro-meteorology. This is one of the objectives of the French ANR project EVNATURB (Assessment of ecosystem performance of a renaturation of the urban environment), in which this study has been carried out.

How to cite: Duffaut, C., Frascaria-Lacoste, N., and Versini, P.-A.: Barriers and levers for implementing sustainable Nature-Based Solutions in cities, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5801, https://doi.org/10.5194/egusphere-egu21-5801, 2021.

EGU21-7039 | vPICO presentations | NH1.4 | Highlight

Examples of Floodplain Restoration Evaluation Studies in the Danube River Basin

Francesca Perosa, Marion Gelhaus, Veronika Zwirglmaier, Leonardo F. Arias-Rodriguez, Aude Zingraff-Hamed, Bernd Cyffka, and Markus Disse

Countries located in the Danube River Basin (DRB) are in danger of being affected by major catastrophic floods along the Danube and its tributaries. Floodplain restoration measures are among win-win nature-based solutions (NBS) for flood risk reduction but practitioners see their limitations in comparison to technical measures, when looking at their effectiveness and profitability. Within the framework of the EU Interreg Danube Floodplain project, this presentation shows the benefits of floodplain restoration in terms of monetized ecosystem services (ES). Our work focused on multiple ES groups for four study areas in the Danube catchment, located in Czech Republic, Romania, Serbia, and Slovenia. This was done with the help of stakeholder engagement, hydrodynamic models results, and the Toolkit for Ecosystem Service Site-Based Assessment (TESSA). Moreover, the approach was complemented with alternative methodologies (e.g. surveys on social media). Results show positive annual combined benefits of floodplain restoration measures, suggesting the helpfulness of evaluating these NBS through ES assessment. The work done will help increasing the knowledge on floodplain and their ES, and on how to rapidly evaluate them. Moreover, it will bring decision-makers further evidence in favor of floodplain restoration measures to be implemented for a general benefit of the communities.

How to cite: Perosa, F., Gelhaus, M., Zwirglmaier, V., Arias-Rodriguez, L. F., Zingraff-Hamed, A., Cyffka, B., and Disse, M.: Examples of Floodplain Restoration Evaluation Studies in the Danube River Basin, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7039, https://doi.org/10.5194/egusphere-egu21-7039, 2021.

EGU21-5858 | vPICO presentations | NH1.4

The reinforcement effect of vegetation on live cribwalls

Alejandro Gonzalez Ollauri, Slobodan Mickovski, Rohinton Emmanuel, and Albert Sorolla Edo

Live cribwalls are Nature-based solutions consisting of timber-based structures acting as retention walls at the toe of slopes and embankments subjected to instability and erosion events. The structure of live cribwalls resembles a multi-level crib made of timber logs from different plant species (e.g. pine, spruce, hazelnut, etc.). The crib structure is then backfilled with earth materials in which locally-available plant cuttings and/or saplings are inserted to establish a dense cover of native vegetation, providing added reinforcement and stability to the cribwall over time; particularly after the complete decay of the timber structure is reached. However, the effect of vegetation on the reinforcement of live cribwalls has not been examined systematically. Information on how vegetation can contribute to reinforce cribwalls hydrologically and mechanically is essential to evaluate the long-term performance of these Nature-based solutions against hydro-meteorological hazards. In this study, we propose a novel conceptual, numerical model based on empirical knowledge to evaluate the reinforcement effect of vegetation on live cribwalls over time. We also demonstrate how the proposed model can be applied to other Nature-based solutions concerned with slope protection and erosion control, such as live gratings or palisades.

How to cite: Gonzalez Ollauri, A., Mickovski, S., Emmanuel, R., and Sorolla Edo, A.: The reinforcement effect of vegetation on live cribwalls, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5858, https://doi.org/10.5194/egusphere-egu21-5858, 2021.

EGU21-8522 | vPICO presentations | NH1.4

156 Nature-based solutions in the German Alps to mitigate hydro-meteorological risks

Aude Zingraff-Hamed, Gerd Lupp, Jonathan Schedler, Josh Huang, and Stephan Pauleit

Nature-based solutions (NBS) are increasingly recognized as robust, sustainable and cost-effective measures for reducing the risk of extreme weather events. Their widespread implementation has become an important goal of the European Union’s political agenda. Many types of measures are included under the umbrella term of NBS. As their number is increasing, knowledge transfer should support effective implementation. Efforts have been made by a number of EU funded projects to develop and assess NBS implementation and enhance the transfer of experience. European databases as OPPLA has been created for this purpose. Interestingly, while mountain areas are highly vulnerable and already have experienced numerous extreme hydro-meteorological events and related natural hazards, NBS implementation in mountain area have received very little attention in both the research and practices until recently. The EU funded project PHUSICOS intends to partly fill this research gap by contributing in the knowledge transfer effort in making an inventory of NBS at their case study sites located in mountain areas. Given this background, the goal of our study is to provide a detailed overview of the NBS implementation effort for the case of German Alps. In this contribution, we present a systematic survey performed in the German Alps. We found 156 solutions implemented. Descriptive and qualitative analyses provided an overview of the implementation efforts in the German Alpine areas. Most of the measures were located within river systems and targeted flood protection. Few measures were implemented in the upper catchment to retain water on the land. Furthermore, few solutions exist to mitigate soil erosion and landslide. Further analysis concentrated on the stakeholders driving the NBS implementation. This survey may help, in the future to develop practical guidelines, identify governance enablers, ease cross-fertilization and identify successfully strategies.

How to cite: Zingraff-Hamed, A., Lupp, G., Schedler, J., Huang, J., and Pauleit, S.: 156 Nature-based solutions in the German Alps to mitigate hydro-meteorological risks, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8522, https://doi.org/10.5194/egusphere-egu21-8522, 2021.

EGU21-9779 | vPICO presentations | NH1.4

Offline Storage Areas as a Natural Flood Management intervention: Evidence from the Evenlode catchment, UK

James Bishop, Gareth Old, Ponnambalam Rameshwaran, Andrew Wade, David Gasca-Tucker, John Robotham, Ann Berkeley, David McKnight, and Jo Old

Catchment-based approaches that work with natural processes for fluvial flood risk reduction are currently the subject of much interest both internationally and in the UK, where they are known as Natural Flood Management (NFM). NFM schemes typically seek to replicate, restore, or enhance natural features of the environment so as to store and/or slow floodwaters during storm events. Benefits over traditional hard-engineered flood management approaches include reduced capital costs and carbon emissions, and they can deliver positive outcomes for both water quality and biodiversity. Despite a small number of studies indicating their potential value, the further uptake of NFM schemes is limited by a lack of empirical evidence demonstrating their effectiveness.

We present results from an intensive monitoring network within a tributary (catchment area 3.4 km2) of the Littlestock Brook, a lowland agricultural catchment within South East England that presents a flood risk to the downstream village of Milton-under-Wychwood. The catchment forms part of the first NFM scheme of its kind within the River Thames basin, currently being delivered in partnership by the Evenlode Catchment Partnership and the Environment Agency as part of a five-year project (2016-2021). Precipitation, stream discharge, and water level within eight offline storage areas have been continuously monitored since September 2019. High resolution topographic surveys of each storage area enable filling, storing, and drainage dynamics to be determined and compared with downstream hydrograph metrics. A series of storm events between October 2019 and February 2020 have provided a unique dataset for investigating the performance of the NFM scheme.

Data from four storms with estimated peak-discharge return periods ranging from 2.7 to 5.5 years demonstrate the potential for reducing peak discharge. During the largest storm, flood volume across the peak of the hydrograph was reduced by 22%, with 64% of total storage capacity remaining unused. Variations in the filling, storing, and drainage characteristics of each storage area have consequences for the overall effectiveness for reducing downstream flood risk and these will be discussed.

How to cite: Bishop, J., Old, G., Rameshwaran, P., Wade, A., Gasca-Tucker, D., Robotham, J., Berkeley, A., McKnight, D., and Old, J.: Offline Storage Areas as a Natural Flood Management intervention: Evidence from the Evenlode catchment, UK, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9779, https://doi.org/10.5194/egusphere-egu21-9779, 2021.

EGU21-14461 | vPICO presentations | NH1.4

Effectiveness of green roofs in reduction of rainfall-fed runoff: A case study in Dublin, Ireland

Bidroha Basu, Arunima Sarkar Basu, Srikanta Sannigrahi, and Francesco Pilla

Increase in extreme rainfall and storm events due to climate change and decrease in water retention in soil due to urbanization has increased the risk of flooding in cities globally. Since majority of the cites are mostly developed, expanding the conventional urban drainage system to account for the excess runoff produced by the rainfall event has limited scope. The challenge is to develop sustainable urban drainage systems (SUDS) to reduce runoff and create a flood control system in major cities. One of the SUDS that are becoming popular is the use of nature-based solutions (NBSs). A set of conventional NBSs to mitigate flood risk include bioswales, bio-retention, tree pits, infiltration trenches. However, even though their performance in flood control is found to be effective, they require considerable land area for deployment, which might be difficult to obtain in cities. For this purpose, green roofs have becoming popular as an alternative NBS in flood control, as it does not require any additional land area for deployment. This study investigates the effectiveness of a green roof in reduction of runoff via real-world case study. A green roof deployed in the CHQ building located at the city centre in Dublin, Ireland has been considered for the study. The green roof has a total size of 70 sq. m. Performance of the green roof in runoff reduction was measured based on rainfall and water retention data collected at four modular units, each having 1 sq. meter area, located at the centre of the roof with an IoT weight scale. The data has been collected for 1 week at 3-minute interval, and the reduction in runoff with and without the presence of the green roof has been estimated. The performance of the green roofs in runoff reduction was found to vary between 20-40% depending on the intensity of storm events.

How to cite: Basu, B., Sarkar Basu, A., Sannigrahi, S., and Pilla, F.: Effectiveness of green roofs in reduction of rainfall-fed runoff: A case study in Dublin, Ireland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14461, https://doi.org/10.5194/egusphere-egu21-14461, 2021.

EGU21-7508 | vPICO presentations | NH1.4

Monitoring Leaky Barriers for Natural Flood Management (NFM) within a community-led project

Gabrielle Powell, Joanna Clark, and Tom Nisbet

Natural Flood management (NFM) is a nature-based solution and catchment-based approach to flood mitigation.  Leaky barriers are a form of NFM and are popular amongst community groups working with natural processes as an affordable and sustainable action that they themselves can implement without investment in large infrastructure. At our research site, over 30 Leaky barriers have been implemented along a mile-long stretch of flashy river by a local community flood group and landowner in an attempt to decrease flood risk downstream in partnership with the Environment Agency. The effectiveness of these leaky barriers is being monitored in a number of ways, including: river flow, river level, geomorphic surveys and time-lapse footage. We describe the project dynamics and operational context that shaped the adopted control-intervention monitoring design. Based on previous studies, we hypothesize that leaky barriers will be most effective at mitigating smaller, rather than large flood events, such as in 2007. This is tested by examining the data collected over 2019-20, which includes storm Dennis (13th-19th February 2020) that caused widespread flooding across England and Wales. The results will contribute to a wider evidence base being collected by the Environment Agency, exploring the context in which community projects and monitoring take place against the changing expectations of funders and the evaluation of data produced.

How to cite: Powell, G., Clark, J., and Nisbet, T.: Monitoring Leaky Barriers for Natural Flood Management (NFM) within a community-led project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7508, https://doi.org/10.5194/egusphere-egu21-7508, 2021.

EGU21-1380 | vPICO presentations | NH1.4 | Highlight

Nature-Based Solutions for Hydro-Meteorological Hazards: the OPERANDUM Database

Laura S. Leo, Sisay Debele, Joy Ommer, Saša Vranić, Zahra Amirzada, Irina Pavlova, Edoardo Bucchignani, Mohammad Aminur Rahman Shah, Alejandro Gonzalez-Ollauri, Slobodan B. Mickovski, Prashant Kumar, Milan Kalas, and Silvana Di Sabatino

Nature-Based Solutions (NBS) refer to the sustainable management, protection and use of nature to preserve the ecosystem and prevent the loss of biodiversity. Given the multiple environmental, social, and economic benefits they provide to society, NBS have been increasingly promoted and implemented in cities, especially for air pollution mitigation and the improving of human thermal comfort and well-being. Several databases and web platforms already exist, which document these beneficial impacts of NBS in our cities by collecting and exposing existing NBS case studies and projects from around globe. However, the effort of cataloging and storing NBS data according to common and harmonized principles and standards seems yet sporadic and uncoordinated at the global and European level, especially in the context of natural hazard-related disasters. Nature-based solutions have been indeed recently emerged as viable and effective measures to mitigate the impacts of hydro-meteorological phenomena such as floods, landslide, etc. in both urban and rural environments, an aspect not often emphasized in the existing databases.

Driven by the ambition of overcoming these two main gaps, an innovative geo-catalogue of existing NBS has been developed within the framework of GeoIKP, the NBS web-platform newly created by the EU H2020 project OPERANDUM.

The geo-catalogue represents a comprehensive, geo-referenced, database of NBS case studies which are specifically designed to mitigate the risk and impacts of hydro-meteorological hazards, under a variety of environmental setting and hazard categories. It therefore represents a novel and open-access data source to learn about, and explore, the usability of NBS in fulfilling climate mitigation and adaptation objectives over a wide range of hydro-meteorological hazards.

Case studies collected from various resources (NBS platforms, scientific literature, technical reports, OPERANDUM living labs, etc.) are revised, classified and harmonized according to internationally recognized standard and classification schemes (e.g., INSPIRE legislation, MAES classification, etc.) which allow to characterize each NBS through a comprehensive set of parameters, including the type of hazard and ecosystem, the societal challenges and driving policies linked to it, the type of intervention and its spatial coverage, among many others.

The highly structured and comprehensive data model adopted here enables to query the database and/or filter the results based on a multitude of individual parameters which encompass all different dimensions of NBS (e.g. geophysical, societal, environmental, etc.). This not only allows for a straightforward and automatic association to one or more thematic aspects of NBS, but also enhances standardization, discoverability and interoperability of NBS data.

How to cite: Leo, L. S., Debele, S., Ommer, J., Vranić, S., Amirzada, Z., Pavlova, I., Bucchignani, E., Shah, M. A. R., Gonzalez-Ollauri, A., Mickovski, S. B., Kumar, P., Kalas, M., and Di Sabatino, S.: Nature-Based Solutions for Hydro-Meteorological Hazards: the OPERANDUM Database, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1380, https://doi.org/10.5194/egusphere-egu21-1380, 2021.

EGU21-7874 | vPICO presentations | NH1.4

Quantifying co-benefits and potential disbenefits of NBS for Disaster Risk Reduction: a practical framework for ex-ante assessment

Joy Ommer, Edoardo Bucchignani, Laura S. Leo, Milan Kalas, Saša Vranić, Sisay Debele, Prashant Kumar, Hannah L. Cloke, and Silvana Di Sabatino

Nature-based solutions are increasingly implemented to tackle disaster risk reduction and climate change adaptation. Their rising popularity over grey solutions is partially explained by their number of additional benefits (so called co-benefits) for the socio-ecological system (SES). Frameworks are available to monitor and assess co-benefits, however, these frameworks are lacking clear guidance and ex-ante quantification of co-benefits and potential disbenefits of NBS. Another limitation is the accessibility and quality (representativeness) of data for computing indicators, especially, going towards larger scales (regional, pan-European). To develop a comprehensive framework and method for assessing and estimating possible side effects in advance, this paper aligns to existing frameworks but goes beyond those by providing practical guidance on data sourcing (including possible proxy variables) and quantification of both co-benefits and disbenefits. The resulting framework will support decision-making on area specific suitability of NBS for disaster risk reduction. Furthermore, it will enhance the planners’ knowledge and understanding of linked processes which can lead to potential positive and negative side effects; thus, this guidance will build a base for selecting suitable locations and NBS interventions.

How to cite: Ommer, J., Bucchignani, E., Leo, L. S., Kalas, M., Vranić, S., Debele, S., Kumar, P., Cloke, H. L., and Di Sabatino, S.: Quantifying co-benefits and potential disbenefits of NBS for Disaster Risk Reduction: a practical framework for ex-ante assessment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7874, https://doi.org/10.5194/egusphere-egu21-7874, 2021.

EGU21-9495 | vPICO presentations | NH1.4 | Highlight

The Open-Air Laboratory Italy

Paolo Ruggieri and the OAL-Italy

The Open-Air Laboratory is a novel concept developed by the EU-funded Operandum project (OPEn-air laboRAtories for Nature baseD solutions to Manage Environmental risk) to co-design, implement and assess the effectiveness of Nature-Based Solutions (NBSs). 

In this work we present the Open-Air Laboratory Italy (OAL-Italy) and discuss the application of the OAL as a framework for the development of innovative NBSs to mitigate the impact of hydro-meteorological hazards in present and future climate.  By combining consolidated practices in an original multidisciplinary frame, the OAL-Italy deploys novel modelling strategies, laboratory measurements and targeted monitoring open-field campaigns. In three operational sites, the NBSs are implemented via a co-design, co-development  and co-deployment approach based on a thorough interaction with key stakeholders. By describing the structure and the approach of the OAL we illustrate salient features of the methodology developed in Operandum that are instrumental for the replicability and the upscaling of the NBSs. 

Presented results address the use of the NBSs to mitigate a range of hydrometeorological hazards such as coastal erosion, flooding, storm surge and salt wedge intrusion. Innovative NBSs tested and developed by the OAL include: deep-rooted plants installed on a river embankment to prevent levee failures, special plants that can live in high salt concentration and remove salt from the river mouth water, an artificial dune and marine seagrass to mitigate the impact of storm surges and coastal erosion. We argue that the OAL constitutes an unprecedented holistic effort towards sustainable land management, adaptation to climate change and the acceptance of Nature-Based Solutions. 

How to cite: Ruggieri, P. and the OAL-Italy: The Open-Air Laboratory Italy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9495, https://doi.org/10.5194/egusphere-egu21-9495, 2021.

EGU21-10094 | vPICO presentations | NH1.4 | Highlight

Design and pre-assessment of NBS for coastal erosion and marine flooding: a case study.

Margherita Aguzzi, Maurizio Bacci, Nunzio De Nigris, Laura Sandra Leo, Maurizio Morelli, Beatrice Pulvirenti, Paola Robello, Paolo Ruggieri, Fabrizio Tavaroli, Silvia Unguendoli, Andrea Valentini, and Carlo Cacciamani

The natural reserve in Sacca di Bellocchio, Lido di Spina (Italy) is affected by frequent marine floods and intense erosive phenomena which threaten the freshwater ecosystem and biodiversity at the site. Floods and erosion are linked to the reduction of river sediment transport and a progressive ground subsidence and sea level rise. The persistence of these conditions and the future rise in sea level can expose neighboring anthropized areas to coastal risk.

This work presents the project of a nature-based solution (NBS) as a possible defense and mitigation action against coastal erosion and marine flooding along the Bellocchio beach. The NBS has been newly designed   within the European project H2020 OPERANDUM (OPEn-air laboRAtories for Nature baseD solutions to Manage Environmental risk) and consists of an artificial sand dune made of natural materials, such as sand, wood, geotextiles and geomembranes through naturalistic engineering techniques. On the new dune will then be inserted native herbaceous and shrubby vegetation. The dune design was supported by an accurate hydro-morphodynamic modeling of the site combined with data concerning the morphological structure, the erosive dynamics and the local climate.

This study discusses in detail the modeling techniques and the monitoring system that guided the design of the dune and that constitute a basis for the assessment of performance and effectiveness of any future NBS intervention at the site. The monitoring campaign is still ongoing and allows the collection of critical and updated information on the impacts of coastal storms, storm surges and flood events in the area. The dataset clearly highlights that the site morphology is constantly changing due to a multitude of factors, such as seasonality, the increasing incidence and/or intensity of coastal storms, sea level rise, etc. These rapid, and sometimes drastic, morphological changes pose a substantial challenge to NBS's design and, most importantly, to its deployment planning and timing phase.

 

How to cite: Aguzzi, M., Bacci, M., De Nigris, N., Leo, L. S., Morelli, M., Pulvirenti, B., Robello, P., Ruggieri, P., Tavaroli, F., Unguendoli, S., Valentini, A., and Cacciamani, C.: Design and pre-assessment of NBS for coastal erosion and marine flooding: a case study., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10094, https://doi.org/10.5194/egusphere-egu21-10094, 2021.

EGU21-11914 | vPICO presentations | NH1.4

Modelling Nature-based Solutions: an application to mitigate coastal erosion

Silvia Unguendoli, Andrea Valentini, Luis Germano Biolchi, Umesh Pranavam Ayyappan Pillai, Alessandri Jacopo, and Pinardi Nadia

Nature based solutions (NBSs) address key societal challenges through the protection, sustainable management and restoration of both natural and modified ecosystems. In this work we present a modeling application of this innovative approach, inspired by nature, with the goal of mitigating coastal erosion. Within the framework of the OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks (OPERANDUM) project, the natural reserve of Bellocchio in Lido di Spina (Italy) faces frequent marine floods and intense erosive phenomena, hence being chosen as Open-Air Laboratory for the NBS implementation. The project aims to mitigate coastal erosion through the realization of an artificial sand dune made of natural materials, such as sand, wood, geotextiles and geomembranes and covered by native herbaceous and shrubby vegetation. We present the modeling activities carried out in the context of the project, aiming on the performance and efficiency evaluation  of the designed NBS, with a specific focus on the coastal morphological modelling. Thus, a numerical modeling chain has been set-up to simulate a long-term current scenario with and without the NBS. The chain is composed of the wave model WAVEWATCH III, the oceanographic model SHYFEM and the morphodynamic model XBeach for the coastal area.

XBeach was validated with available and specific (for the project) topo-bathymetric surveys of the area of interest as means to define the more accurate set-up of the model parameters. The 10 years period 2010-2019 was defined as the time range for modelling simulations. Sea level outputs from SHYFEM and wave outputs from WAVEWATCH III for the 10 years simulations are used to force the coastal model XBeach. Given the huge computational costs related to long-term simulations, an input-schematization was applied (so called “input reduction”). The approach followed for the long-term morphodynamic modelling of the NBS-XBeach setting will be shown. Moreover, the chosen coastal model domain, the model set-up and the input reduction applied will be presented.

How to cite: Unguendoli, S., Valentini, A., Germano Biolchi, L., Pranavam Ayyappan Pillai, U., Jacopo, A., and Nadia, P.: Modelling Nature-based Solutions: an application to mitigate coastal erosion, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11914, https://doi.org/10.5194/egusphere-egu21-11914, 2021.

EGU21-14269 | vPICO presentations | NH1.4

Supporting co-development phase of Nature Based Solution by combined use of Earth Observation and modeling

Silvia Maria Alfieri, Fatemeh Foroughnia, Beatrice Pulvirenti, Paolo Ruggieri, Margherita Aguzzi, Roderik Linderberg, Nunzio De Nigris, Maurizio Morelli, Fabrizio Tavaroli, Silvia Unguentoli, Andrea Valentini, Paola Robello, Carlo Cacciamani, and Massimo Menenti

A protected natural area in the Emilia Romagna region, Northern Italy is threatened by hydro-meteorological hazards, particularly sea storms. In the last 50 years the northern part of the Bellocchio Park (Sacca Bellocchio II Nature Reserve, Site code EUAPP0072 - Ferrara, Italy)  was interested by an intensive urbanization (Lido di Spina) with the realization of infrastructures, e.g. roads and residential settlements. This land use change led to the construction of embankments and to the conversion of wetlands. These modifications, in combination to even more frequent storm surge events increased coastal erosion. In addition, inland flooding caused by storm surges acts with the reduction of the lagoon and the increase of soil salinity. As an example, the last event occurred in December 2020  eroded a large portion of the Bellocchio beach.   

Co-design, co-development and deployment of NBS solutions to reduce storm surge risk in the Bellocchio Park is one of the objectives of the H2020 project OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks (OPERANDUM). BellocchioBellochio park is in fact one of the 10 Open Air Laboratories (OAL) where the evidence of mitigation of hydro-meteorological risk by NBS will be demonstrated by the combination of different models, approaches and data.

During the co-design process in the Bellocchio park, potential deployment locations of sand dunes have been identified in collaboration with local authorities devoted to the management of the natural area and to the coast defense (CB and ARSTePC-RER) and an environmental engineering consultant assisting Arpae (IRIS sas). Field visits were devoted to the analysis of the environmental features, strengths and weaknesses of candidate sites.

This work aims to explore the usefulness of the combined use of multisource remote sensing and modeling in decision making during the co-design process of a NBS. The impacts of the most intense extreme storm surge events in the last 30 years have been documented by delineating flooded areas along the coast using Synthetic Aperture Radar and Multispectral image data. Coastal erosion has been also described by means of change detection analysis and very high resolution multispectral EO data. This screening has given a picture of areas at the risk, i.e. the area most likely to be affected by storm-surge events. Auxiliary data like Digital Terrain Models has been assimilated in a dedicated model to produce flood maps under different scenarios, i.e. different locations and size of NBS and different intensities of storm surge.  

The integrated analysis was helpful in defining the priority sites, among the ones defined by the stakeholders and engineers, in term of effectiveness for storm surge risk reduction.

How to cite: Alfieri, S. M., Foroughnia, F., Pulvirenti, B., Ruggieri, P., Aguzzi, M., Linderberg, R., De Nigris, N., Morelli, M., Tavaroli, F., Unguentoli, S., Valentini, A., Robello, P., Cacciamani, C., and Menenti, M.: Supporting co-development phase of Nature Based Solution by combined use of Earth Observation and modeling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14269, https://doi.org/10.5194/egusphere-egu21-14269, 2021.

EGU21-8012 | vPICO presentations | NH1.4 | Highlight

Evaluating nature-based solutions in a non-stationary climate with changing risk of flooding

Sisay Debele, Jeetendra Sahani, Silvia Maria Alfieri, Paul Bowyer, Nikos Charizopoulos, Michael Loupis, Massimo Menenti, Fabrice Renaud, Mohammad Aminur Rahman Shah, Christos Spyrou, Thomas Zieher, Silvana Di Sabatino, and Prashant Kumar

Abstract

Under climate change scenarios, it is important to evaluate the changes in recent behavior of heavy precipitation events, the resulting flood risk, and the detrimental impacts of the peak flow of water on human well-being, properties, infrastructure, and the natural environment. Normally, flood risk is estimated using the stationary flood frequency analysis technique. However, a site’s hydroclimate can shift beyond the range of historical observations considering continuing global warming. Therefore, flood-like distributions capable of accounting for changes in the parameters over time should be considered. The main objective of this study is to apply non-stationary flood frequency models using the generalized extreme value (GEV) distribution to model the changes in flood risk under two scenarios: (1) without nature-based solutions (NBS) in place and; (2) with NBS i.e. wetlands, retention ponds and weir/low head dam implemented. In the GEV model, the first two moments i.e. location and scale parameters of the distribution were allowed to change as a function of time-variable covariates, estimated by maximum likelihood. The methodology is applied to OPEn-air laboRAtories for Nature baseD solUtions to Manage hydro-meteo risks, which is in Europe. The time-dependent 100-year design quantiles were estimated for both the scenarios. We obtained daily precipitation data of climate models from the EURO-CORDEX project dataset for 1951–2020 and 2022–2100 representing historical and future simulations, respectively. The hydrologic model, HEC-HMS was used to simulate discharges/flood hydrograph without and with NBS in place for these two periods: historical (1951-2020) and future (2022-2100). The results showed that the corresponding time-dependent 100-year floods were remarkably high for the without NBS scenario in both the periods. Particularly, the high emission scenario (RCP 8.5) resulted in dramatically increased flood risks in the future. The simulation without NBS also showed that flooded area is projected to increase by 25% and 40% for inundation depth between 1.5 and 3.5 m under RCP 4.5 and RCP 8.5 scenarios, respectively. For inundation depth above 3.5 m, the flooded area is anticipated to rise by 30% and 55% in both periods respectively. With the implementation of NBS, the flood risk was projected to decrease by 20% (2022–2050) and 45% (2071–2100) with a significant decrease under RCP 4.5 and RCP 8.5 scenarios. This study can help improve existing methods to adapt to the uncertainties in a changing environment, which is critical to develop climate-proof NBS and improve NBS planning, implementation, and effectiveness assessment.

Keywords: Nature-based solutions; flood frequency analysis; climate change; wetlands; GEV model

Acknowledgments

This work has been carried out under the framework of OPERANDUM (OPEn-air laboRAtories for Nature baseD solUtions to Manage hydro-meteo risks) project, which is funded by the European Union's Horizon 2020 research and innovation programme under the Grant Agreement No: 776848.

How to cite: Debele, S., Sahani, J., Alfieri, S. M., Bowyer, P., Charizopoulos, N., Loupis, M., Menenti, M., Renaud, F., Shah, M. A. R., Spyrou, C., Zieher, T., Di Sabatino, S., and Kumar, P.: Evaluating nature-based solutions in a non-stationary climate with changing risk of flooding, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8012, https://doi.org/10.5194/egusphere-egu21-8012, 2021.

EGU21-10696 | vPICO presentations | NH1.4

Geo-environmental analysis of terraced slopes and dry-stone walls in Can Grau area (Garraf Park, Catalunya, Spain): preliminary results from the Stonewalls4life project.

Andrea Mandarino, Andrea Vigo, Andrea Cevasco, Patricia Varona Prellezo, Emilio Valbuena-Ureña, Abraham Guillén-Villar, Montserrat Traver-Vives, Dolors Garcia-Martínez, and Marco Firpo

Stonewalls4life is an E.U. Life project started in the second half of 2019 involving many subjects, both public bodies and privates, in a multidisciplinary working group. The main objective of the project is to demonstrate how an ancient technology for land use, drystone walling, can be effectively considered to improve the resilience of the territory to climate change by adopting a socially and technically innovative approach.

The project actions are being performed at Manarola, within the Cinque Terre National Park (eastern Liguria, north-western Italy). The pilot site is a narrow strip of land close to the seaside and characterized by small valleys with steep terraced slopes. This anthropogenic landscape represents a high-value peculiarity attracting more than three million tourists every year.

Three replication sites were identified in order to demonstrate the transferability and replicability of the project actions: two are located within the Cinque Terre Natural Park territory and one is in the Can Grau area (Garraf Park, Catalunya, Spain).

The Spanish site is currently under evaluation. An extensive geological, geomorphological, and land-use-land-cover (LULC) analysis is now being carried out in the Can Grau area to define its environmental features, especially concerning geological aspects and land use, and focusing on terraced areas and their state of conservation. This study aims to identify a specific suitable site for the replication of the project actions that will be carried out in Manarola, namely for dry-stone walls recovery, and is based on a multitemporal analysis of aerial images performed in a GIS environment and a wide collection and review of bibliographic data.

This contribution illustrates the preliminary results of the Can Grau area analysis, focusing in particular on the distribution of terraced areas and the variation of LULC from the 1950s to the present day. From this study emerges a progressive abandonment of terraced areas used for cultivation, although, according to historical sources, this process mostly occurred after the phylloxera appeared in the late 19th century, seriously affecting the most important agricultural activity in the Garraf, namely the viticulture.

The outcomes from this study will be useful in terms of both Stonewalls4life project implementation and overall land management, particularly aiming to restore a man-made geomorphological heritage and mitigate geo-hydrological risk.

How to cite: Mandarino, A., Vigo, A., Cevasco, A., Varona Prellezo, P., Valbuena-Ureña, E., Guillén-Villar, A., Traver-Vives, M., Garcia-Martínez, D., and Firpo, M.: Geo-environmental analysis of terraced slopes and dry-stone walls in Can Grau area (Garraf Park, Catalunya, Spain): preliminary results from the Stonewalls4life project., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10696, https://doi.org/10.5194/egusphere-egu21-10696, 2021.

EGU21-10465 | vPICO presentations | NH1.4

Nature Based Solution simulation design methods – A storm surge seagrass application

Umesh Pranavam Ayyappan Pillai, Nadia Pinardi, Ivan Federico, Salvatore Causio, Jacopo Alessandri, Silvia Unguendoli, and Andrea Valentini

Nature Based solutions (NBS) have been presented in the recent past as a potential solution to natural and climate change adverse effects on human well-being and socio-economic activities.  In this study, we present a simulation design methodology for NBS that can mitigate the effect of storm surges and coastal erosion. The chosen NBS is marine seagrass and it will be applied to the coastal strip of the Emilia-Romagna coasts. Within the framework of the OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks (OPERANDUM) project, the seagrass NBS is presented within a simulation design methodology consisting of the comparison between validated wave numerical simulations for the present climate and modified wave simulations with marine seagrass. In this context, the unstructured version of WAVEWATCH III (WW3) model has been implemented for simulating the wave characteristics across the Emilia-Romagna coastal strip with and without seagrass.

The calibration/validation of WW3 was carried out and sensitivity experiments using the various wind-input dissipation source packages and bottom friction formulations were also attempted to evaluate the model performances (validation results presented here are for the entire 2017 year). The ST6 physics along with SHOWEX bottom friction formulations were chosen ideal for the study area. To evaluate the model results a directional wave rider buoy data was utilized. The model simulated significant wave parameters namely Hs (significant wave height), Tm (mean wave period) were compared with buoy observations and high correlations (0.93) were found with Hs comparison. Further the WW3 model was modified by including the modified bottom dissipation stress due to submerged vegetation, thereby incorporating the NBS as a potential mechanism for wave amplitude reduction. The seagrass species ‘Zostera marina’ was chosen in this study and comparisons showed that seagrass is capable to reduce the wave energy in the study area. Furthermore, the dependence on seagrass plant high-density and low-density scenarios, together with seagrass parameters (height and width of the seagrass) and species show the sensitivity of the results even on reduction of wave energy as obtained with different degrees by all NBS scenarios.    

Keywords: Nature-based solutions, WW3, marine seagrass, storm surge, Zostera marina.

How to cite: Pranavam Ayyappan Pillai, U., Pinardi, N., Federico, I., Causio, S., Alessandri, J., Unguendoli, S., and Valentini, A.: Nature Based Solution simulation design methods – A storm surge seagrass application, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10465, https://doi.org/10.5194/egusphere-egu21-10465, 2021.

EGU21-8018 | vPICO presentations | NH1.4

Heatwave risk for two regions of the UK: Aberdeenshire and South East England 

Jeetendra Sahani, Sisay Debele, and Prashant Kumar

Global warming due to anthropogenic emission of green-house gases has induced climate change which is disturbing and will continue to impact the ecology and energy balance of our earth environment. The duration, frequency and intensity of extreme hot days in summers called heatwaves have increased with the beginning of the 21st century worldwide and have been projected to increase. Associated human health loss or damage can be managed or mitigated by planning proper management strategies, such as nature-based green and/or blue solutions in advance, along with proper evaluation of the risk of heat. Since heat stress is more pronounced in urban and built areas, most studies for heatwave risk assessment have been limited to big cities. The risk variation in semi-urban, sub-urban and rural areas has not been much investigated. The heat risk develops with time because of changing climate and socio-demographics, and risk assessment is needed to be done utilising recent data on climate and population characteristics. In this study, the heatwave or extreme hot (99 percentile) temperature risk has been estimated by using statistical approach on summer daily temperature and mortality data from Aberdeenshire and South East (SE) England, UK for the duration 1981-2018. A distributed-lag nonlinear model from Poisson regression family was applied to model the relationship between daily temperature and mortality. We calculated relative risk (RR) and mortality attributable fraction (AF) due to high temperature by comparing the extreme heat with the minimum mortality temperature. AF was calculated by dividing the number of excess deaths due to heat from all the days of the time-series by the total number of deaths. The overall risk in SE England was noted 56 % higher (RR 1.067) than Aberdeenshire (RR 1.043), with 36% more excess death in SE England (AF 0.15% and 0.11% respectively) due to different levels of people’s adaptation and resilience to different climate conditions.  The outcome of this study can help in site focused mitigation strategies to certain areas at most risk and develop a scientific framework for early warning, planning and managing the health impacts of heatwave in more rustic regions.

 

Acknowledgements: This work is supported by the European Union's Horizon 2020 research and innovation programme; funded by and carried out within the framework of OPERANDUM project (Grant no. 776848).

How to cite: Sahani, J., Debele, S., and Kumar, P.: Heatwave risk for two regions of the UK: Aberdeenshire and South East England , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8018, https://doi.org/10.5194/egusphere-egu21-8018, 2021.

EGU21-13481 | vPICO presentations | NH1.4

“Stakeholder engagement strategy: monitoring and evaluate the impact in OPERANDUM project”

Teresa Carlone, Matteo Mannocchi, Edoardo Bucchignani, Paolo Ruggeri, Laura Sandra Leo, Beatrice Pulvirenti, Annemarie Polderman, Depy Panga, Katriina Soini, and Zahra Amirzada

The OPERANDUM project is designed to address major hydro-meteorological risks through the deployment and assessment of Nature-Based Solution (NBS). The project pursues a co-creation approach and sets up 7 Open Air Laboratories (OAL) in which a user-centric method, characterized by the active participation of the stakeholders, is promoted. Stakeholder engagement in co-designing, co-developing, and co-deploying NBS is becoming a prominent practice in environmental projects and a crucial part of the process is monitoring and impact evaluation of the engagement strategy and actions. Monitoring aims at providing information about the stakeholder engagement processes throughout the project and should not be seen as a separate part of the stakeholder engagement processes or an aim in itself but as a continuous and integral element of the co-creation process. The poster shows the results of preliminary empirical research conducted among the OALs in order to propose some key indicators useful to evaluate the process and the impact generated by the OPERANDUM co-creative approach.  Starting from a theoretical framework, the research selected and discussed some crucial indicators in order to propose an action plan for the monitoring and impact evaluation of OPERANDUM strategy to involve and support the participation of stakeholders, with a specific focus on the tools used so far and those that are in the pilot phases (i.e Stakeholder Forum experimented in OAL Italy). Both qualitative and quantitative methods have been included in the evaluation for the engagement strategy outcome of the projects to be fully understood and, not secondarily, to identify a sustainability strategy beyond the conclusion of OPERANDUM to reinforce the social acceptance, the shared knowledge, and the upscaling of NBS at local, national and global level.

How to cite: Carlone, T., Mannocchi, M., Bucchignani, E., Ruggeri, P., Leo, L. S., Pulvirenti, B., Polderman, A., Panga, D., Soini, K., and Amirzada, Z.: “Stakeholder engagement strategy: monitoring and evaluate the impact in OPERANDUM project”, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13481, https://doi.org/10.5194/egusphere-egu21-13481, 2021.

Rainfall-induced floods and landslides have occurred and caused devastating impacts in recent years in Japan, and adaptation to natural disaster risks is a key to the sustainability of local communities. Traditional ecological knowledge in Japanese communities exists abundantly, such as those in disaster risk reduction and natural resource use, and it has been passed down from generation to generation. These traditional knowledge and skills have been used to benefit from nature’s gifts or ecosystem services as well as to avoid devastating impacts from natural disasters. Collaboration and cooperation by diverse stakeholders are crucial for recognizing and utilizing traditional ecological knowledge in actual solutions and actions. In this presentation, I introduce how traditional ecological knowledge has been used in disaster risk reduction in Mikatagoko Lakes area located in Fukui Prefecture, Japan. Rainfall-induced floods occur frequently in this area, but traditional land use helps to reduce inundation damage of houses and conserve biodiversity and ecosystem services including local food culture. Embankment built around the lakes has been renovated not only for flood risk reduction but also for biodiversity conservation, also supported by traditional ecological knowledge in this area. The Mikatagoko nature restoration committee, in which diverse local stakeholders participate and collaborate, has played a significant role in these actions and solutions. Our experiences suggest that transdisciplinary ecosystem-based approaches contribute to the sustainability of local communities and the collaborative platform among local stakeholders is important in taking advantage of traditional ecological knowledge in actual solutions and actions.

How to cite: Yoshida, T.: Transdisciplinary ecosystem-based approaches to flood risk reduction supported by traditional ecological knowledge in Mikatagoko Lakes, Japan, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5678, https://doi.org/10.5194/egusphere-egu21-5678, 2021.

EGU21-14404 | vPICO presentations | NH1.4 | Highlight

A citizen-oriented understanding of nature-based innovations: A case study in Dublin, Ireland

Arunima Sarkar Basu, Bidroha Basu, Srikanta Sannigrahi, and Francesco Pilla

Hydro-meteorological hazards such as floods have been a long-standing challenge for urban planners. A substantial increase in urbanization has undeniably pressurized the existing drainage network which has increased the flood proneness. The OPERANDUM project (H2020, grant agreement No 776848) has proposed a unique methodology for handling urban flooding by setting up open-air laboratories (OALs). As a pilot study of open-air laboratory Ireland (OAL-IE), an interdisciplinary methodology is adapted. Flood modeling techniques are identified for better flood risk assessment and flood management. Nature-based innovations are proposed to help identify and improve the existing urban drainage systems. The adaptability of nature-based systems and their efficacy as a supplemental tool to better flood management is a predominant and significant question. The awareness of citizens on their experience, challenges, and narratives are an equally reliable parameter to examine whether the spatio-temporal viability of new flood management techniques through nature-based innovations is a promising path for sustainable urban management. The intermittent relationship of flood hazard and the citizen access to infrastructure such as schools, childcare, old age homes, offices, transportation network holds a place of relevancy. The dynamics of “lived experiences” can help urban planners to pull out the traditional and formal strategies to be implemented for better liveability of citizens. Moreover, the willingness of citizens to maintain and share activities for co-deployment as a successful participatory process for innovative nature-based solutions support the social purpose of the OPERANDUM project. This research focuses on understanding the social background, cognitive thinking, and ideology that holds unique opportunities to OAL-IE for potential retrospective interpretation of nature-based innovations. A detailed survey with the stakeholders is aimed to understand their perspective on flooding, to identify how and where nature-based innovations can assist the city council to develop an efficient sustainable flood management system. This information on how citizens perceived and attributed the delivery of nature-based innovation can provide guidelines for developing better flood management and mitigation policies in Dublin.

How to cite: Sarkar Basu, A., Basu, B., Sannigrahi, S., and Pilla, F.: A citizen-oriented understanding of nature-based innovations: A case study in Dublin, Ireland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14404, https://doi.org/10.5194/egusphere-egu21-14404, 2021.

EGU21-4579 | vPICO presentations | NH1.4 | Highlight

Public acceptance of nature-based solutions (NbS): a framework for successful NbS and its application in three European case studies

Carl C. Anderson, Fabrice G. Renaud, Stuart Hanscomb, Michael Loupis, Karen E. Munro, Alejandro Ollauri, Depy Panga, Eija Pouta, Katriina Soini, and Craig S. Thomson

Nature-based solutions (NbS) are increasingly recognized as sustainable approaches to address socio-environmental challenges. Disaster risk reduction (DRR) has benefited by increasingly moving away from purely ‘grey’ infrastructure measures towards NbS, which can better provide cultural, aesthetic, and recreational co-benefits that are highly valued among European citizens. Public acceptance is of particular importance for NbS since they often rely on collaborative implementation, management, and monitoring, as well as protection against competing land uses. Although public engagement is a common goal of NbS projects and found in the IUCN’s core principles of NbS, outreach efforts are rarely based on a sufficient understanding of the (de)motivating factors tied to public perceptions. As a first step, we conducted a systematic literature review to examine how unique NbS characteristics relate to public acceptance through a comparison with grey measures. We identified influential acceptance factors related to individuals, society, and DRR measures. Based on the review, we introduce the PA-NbS framework as a starting point for the systematic consideration, design, and testing of strategies for increasing public acceptance. The PA-NbS highlights the roles of trust, competing interests, and effectiveness of NbS, as well as public perceptions of risk, nature and place.

A lack of consideration of these factors may lead to misaligned public expectations and failed participatory initiatives, while jeopardizing the success of NbS projects. Therefore, as a second step, we conducted citizen surveys within three NbS host communities. Distinct NbS being implemented within the OPERANDUM project aim to reduce risk from (socio-)natural hazards in Scotland (landslides and coastal erosion), Finland (eutrophication and algal blooms) and Greece (river flooding). Associations of factors related to risk, nature, and place perceptions with pro-NbS attitudes and behavior were tested to determine how these may be leveraged to increase acceptance. We find that trust is a consistent factor for defining attitudes towards the NbS across the sites. Attitudes are strongly associated with respondents’ commitment to nature and concern for risk, while some skepticism of NbS effectiveness leads to high public demand for relevant evidence. Risk perception and particularly the potential for future impacts are associated with behavioural acceptance (i.e. willingness to engage), along with responsibility for nature and connectedness to place.

Current data collection efforts to demonstrate NbS effectiveness for risk reduction are well-positioned to increase public acceptance in Europe. However, recognizing the differences among segments of the public within each site along with distinct hazard types, proposed NbS, and historical, social, and cultural characteristics across the sites is crucial for designing strategies that increase acceptance. An overview of these dynamics leads to evidence-based recommendations for the case-study sites and for successful NbS in Europe.

How to cite: Anderson, C. C., Renaud, F. G., Hanscomb, S., Loupis, M., Munro, K. E., Ollauri, A., Panga, D., Pouta, E., Soini, K., and Thomson, C. S.: Public acceptance of nature-based solutions (NbS): a framework for successful NbS and its application in three European case studies, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4579, https://doi.org/10.5194/egusphere-egu21-4579, 2021.

EGU21-15131 | vPICO presentations | NH1.4

Co-design and co-deployment of nature based solutions for river flooding mitigation in northern Italy river embankments

Beatrice Pulvirenti, Paolo Ruggieri, Alessio Domeneghetti, Elena Toth, Silvia Maria Alfieri, Fatemeh Foroughnia, and Massimo Menenti

Po valley in the Emilia Romagna region, Northern Italy, is threatened by hydro-meteorological hazards, such as river flooding. In the last 50 years this area was interested by an intensive urbanization (with cities that span from the size of a village to metropolitan urban areas such as Bologna) with the realization of infrastructures, e.g. roads and residential settlements near rivers. In addition, the strengthening and expansion of the embankment system led to the development of the areas prone to floods located nearby the rivers. These modifications, in combination with the occurrence of high flood peaks recently experienced in this area have increased the impacts and thus, the attention, on riverine floods. The last event occurred in December 2020, where Panaro river, a tributary of the Po river, broke its banks near Modena causing large flooded area.

Co-design and co-deployment of nature based solutions (NBS) to reduce flooding risk in the Panaro river is one of the objective of the H2020 project OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks (OPERANDUM). A portion of the Panaro river embankment is one of the Open Air Laboratories (OAL) where special deep rooted plants were implemented to evidence the mitigation of hydro-meteorological risks by NBS.

In this work, a combined approach between Earth Observation (EO) data and multi-scale modelling is shown, to support the co-design process of the NBS. Synthetic Aperture Radar (SAR) and optical EO data were used to identify areas at risk, i.e. the area most likely to be affected by severe flooding events.  A thresholding method was applied to the SAR and optical images available during past extreme events to identify size and location of the floods. The remote sensing analysis allowed the definition of specific portions of the Panaro river where NBS can be more effective for flood risk reduction. In a second step, a multi-scale modelling approach, based on the characterisation of deep-rooted plants by laboratory experiments and in-field measurements, is used to determine the response of the identified portions of Panaro river to flooding events and to evaluate the effectiveness of possible NBS.

Remote sensing analysis indicates that the area between Secchia and Panaro rivers, delimited to the north by the town of Bomporto and to the South by the town of Albareto has been most frequently inundated in the recent extreme events. The integrated analysis leads to the identification of potential sites, along the Panaro river, where NBS could be effective for river flooding risk reduction, contributing to the definition of the priority sites among the ones defined by the stakeholders and engineers.

How to cite: Pulvirenti, B., Ruggieri, P., Domeneghetti, A., Toth, E., Alfieri, S. M., Foroughnia, F., and Menenti, M.: Co-design and co-deployment of nature based solutions for river flooding mitigation in northern Italy river embankments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15131, https://doi.org/10.5194/egusphere-egu21-15131, 2021.

EGU21-15504 | vPICO presentations | NH1.4

The ecosystem service benefits of green-roof as a part of smart ecosystem-based management: A case study in Dublin, Ireland

Srikanta Sannigrahi, Bidroha Basu, Arunima Sarkar Basu, and Francesco Pilla

The concept of Ecosystem-Based Management (EBM) as part of Nature-Based Solutions (NBS) have frequently been adopted in different strategic planning as a cross-sectoral mechanism to manage environmental problems. The EBM combines all relevant approaches, methods, tools, and software that collectively provide key scientific and socioeconomic evidence and eventually address environmental issues more sustainably. The specific application of EBM in different environmental problems, including flooding, have been proven effective in many cases. This ensures the superiority of EBM approaches for designing collaborative programs for solving environmental problems. The EBM offers a variety of sustainable interventions such as reducing impervious surface through porous paving, green parking lots, brownfield restoration, and deployment of green-roofs, which collectively attenuates water runoff and peak discharge, and offers protection against extreme precipitation events by enhancing water infiltration. In addition to the targeted benefits and cost-effectiveness of EBM, the supply of potential ecosystem service co-benefits that usually comes with EBM can contribute substantially to generating environmental benefits and adds community well-being. In order to analyse the superior effects of green-roof as a part of a smart-EBM framework, which has been deployed in CHQ building in Dublin, Ireland, a conceptual upscaling scenario framework has been formulated for measuring the city scale impact of green-roofs in providing multiple-valued ecosystem services. The biophysical and economic benefits of smart green-roof EBM will be estimated using varied ecosystem service modelling and standard cost-benefit analysis. The proposed smart green-roof framework is expected to have a more significant impact in minimising the flooding problems in Dublin city and expected to provide multiple regulating, supporting provisioning, and cultural benefits that can collectively surpass the deployment cost of green-roofs in the long run.

How to cite: Sannigrahi, S., Basu, B., Basu, A. S., and Pilla, F.: The ecosystem service benefits of green-roof as a part of smart ecosystem-based management: A case study in Dublin, Ireland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15504, https://doi.org/10.5194/egusphere-egu21-15504, 2021.

EGU21-15937 | vPICO presentations | NH1.4 | Highlight

Identification and Evaluation of Ecosystem-based Approaches for Flood Risk Reduction in the Transboundary Lower Mono River Catchment in Benin and Togo

Lorina Schudel, Yvonne Walz, and Kokouvi Gbétey Akpamou

Floods in West Africa repeatedly cause devastating impacts on human life and livelihoods, infrastructure and the environment and they are expected to increase in frequency and severity under a changing climate. Ecosystem-based approaches can be a cost-effective, efficient way to reduce flood risk while at the same time providing co-benefits. However, qualitative and quantitative assessments of ecosystem-based approaches that are suitable for the climatic conditions and socio-ecological system of the region are scarse. This study therefore identifies and evaluates climate-sensitive ecosystem-based approaches for the transboundary Lower Mono River Basin in Benin and Togo. The identification of ecosystem-based approaches has been done based on a review of scientific literature and complemented by a participatory approach with experts from the catchment. During focus group discussions, national stakeholders and policy makers identified, prioritized and mapped existing measures and provided their perspectives on prospective measures to reduce flood risk in the transboundary catchment. They include measures to reduce flow velocity, increase soil infiltration and improve water management. In a next step, we used a multi-criteria analysis considering ecological, climatic and flood hazard data to create suitability maps for different clusters of identified ecosystem-based approaches. This study is part of the CLIMAFRI project, which aims at creating a river basin information system for the Lower Mono Basin as well as creating a flood risk management plan. Through the integration of the suitability maps into the flood risk assessment tool, which has been created in the scope of this project, the ecosystem-based approaches are evaluated quantitatively. In a second round of focus group discussions with representatives from the local communities, feasibility of selected ecosystem-based approaches, co-benefits and trade-offs of the measures are discussed. Through the combination of qualitative and quantitative data, a holistic evaluation of ecosystem-based approaches and their contribution to hazard mitigation, increase of coping capacity, ecosystem resilience and overall flood risk reduction can be achieved.

How to cite: Schudel, L., Walz, Y., and Akpamou, K. G.: Identification and Evaluation of Ecosystem-based Approaches for Flood Risk Reduction in the Transboundary Lower Mono River Catchment in Benin and Togo, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15937, https://doi.org/10.5194/egusphere-egu21-15937, 2021.

NH1.5 – Hazard Risk Managment in Agriculture and Agroecosystems

EGU21-1169 | vPICO presentations | NH1.5

Future climate risk to UK agriculture from heat and humidity changes

Freya Garry, Dan Bernie, Jemma Davie, and Edward Pope

Assessments of current and future climate risk are required for adaptation planning to increase resilience and enable society to cope with future climate hazards. Here we identify case studies of compound hazard (involving heat and humidity) events of interest to the UK agricultural sector and present a framework for comparing the frequency and duration of compound events now to those projected in 50 years’ time. We use high resolution (12 km) simulations from the UK Climate Projections to explore how the frequency and duration of instances of potato blight and thermal heat stress to dairy cattle may change locally under RCP 8.5 emissions forcing. We combine hazard (temperature and humidity data) with vulnerability (specific threshold exceedance) and exposure (regional dairy cattle numbers/potato growing area) to estimate risk. Regions where most potatoes are grown, and where the potato blight risk is greatest in both the current and future climate, include the East of England, Yorkshire and the Humber and Eastern Scotland. By 2070, potato blight occurrences may increase by 70 % in East Scotland and between 20 - 30 % across the East of England, the Midlands and Yorkshire and the Humber. Assuming dairy cattle spatial distributions remain the same, the area of greatest risk now and in the future is South West England, with notable increases in risk across Northern Ireland, Wales, the Midlands, North West England and North West Scotland. Dairy cattle heat stress (using a temperature-humidity index) is projected to increase by over 1000 % in South West England, the region with the most dairy cattle. Finally, we consider projected changes to UK seasons, using 2018 as a template, where a cold spring followed by a warm/dry summer resulted in hay/silage shortages. In addition to reduced crop yields in 2018, cattle were kept inside for longer in the cold spring and in the warm/dry summer, due to heat stress and poor grass quality. UK Climate Projections indicate that the annual probability of cold spring/warm summer conditions will decrease in future, but the annual probability of longer dry/warm summers will increase. We conclude that the agricultural sector should consider suitable climate adaptation measures to minimise the risk of dairy cattle thermal heat stress, increased potato blight, and longer dry/warm summer conditions.

How to cite: Garry, F., Bernie, D., Davie, J., and Pope, E.: Future climate risk to UK agriculture from heat and humidity changes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1169, https://doi.org/10.5194/egusphere-egu21-1169, 2021.