High majority of soil erosion studies focus on cereal croplands, vineyards, olive, avocado, citrus, almond, persimmon, apple, and apricot orchards. To date, there is a lack of information about the possible impacts of tillage management on soil properties and hydrological response in fig orchards. Understanding this will be crucial to design efficient soil conservation practices and degradation control. Therefore, the aim of this research was to study the initial soil erosion in fig plantations and temporal evolution of initial soil erosion after the tillage intervention on undeveloped, Calcic Fluvisol in Dalmatia, Croatia. The study was conducted by collecting undisturbed soil samples, followed by rainfall simulations (58 mm h^-1, during 30 min, over 0.785 m² plots) in eight repetitions per measurement 2 days, 1 month, and 3 months after the intensive tillage. The results showed a clear difference among soil properties trough time. Seasonal effect significantly modifies soil properties and hydrological response. Soil bulk density and mean weight diameter increase (p < 0.05), while water holding capacity, water stable aggregates, soil organic content, and available phosphorus decrease (p < 0.05) by time after tillage_. The highest runoff was measured 1 month (100.5 m³ ha^-1), followed by 3 months (82 m³ ha^-1), and 0 months (48.3 m³ ha^-1) after tillage. Sediment losses were highest at 3 months (3488.9 kg ha^-1), followed by 3.5 times lesser losses at 1 month (990.6 kg ha^-1), and 8.2 times lower right after the tillage (426.1 kg ha^-1). Temporal variations of soil erodibility in this study were under the influence of soil natural consolidation and precipitation. Fig orchards on young, undeveloped soils are highly erodible forms of land use and conservation practices need to be deploy in order to mitigate land degradation.

Keywords: soil physical properties, runoff, permanent plantation, short-term changes, undeveloped soil

Acknowledgments

This work was supported by Croatian Science Foundation through the project "Soil erosion and degradation in Croatia" (UIP-2017-05-7834) (SEDCRO).

How to cite: Bogunovic, I., Telak, L. J., Dugan, I., Ferreira, C. S. S., and Pereira, P.: Tillage-induced management impact on soil properties and initial soil erosion in degraded calcareous soils in Mediterranean fig orchard, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1309, https://doi.org/10.5194/egusphere-egu21-1309, 2021.

Soil quality indexes (SQIs) are very useful in assessing the status and edaphic health of soils. This is particularly the case in the Mediterranean area, where successive torrential rainfall episodes give rise to erosion and soil degradation processes; these are being exacerbated by the current climate crisis. The objective of this study was to analyze the soil quality in two contrasting Mediterranean watersheds in the province of Malaga (Spain): the middle and upper watersheds of the Rio Grande (sub-humid conditions) and the Benamargosa River (semi-arid conditions). Field soil sampling was carried out at representative sites, and the soils were subsequently analyzed for various edaphic properties in the laboratory. From the resulting data, the mean values ​​have been grouped and reclassified, and based on a multicriteria evaluation, a SQI for the study region was generated. The results show that there are major differences between the two watersheds, with optimal soil quality values being found in the Rio Grande watershed, but more unfavorable values occurring throughout most of the Benamargosa River watershed.

How to cite: Sillero-Medina, J. A., Hueso-Gonzalez, P., and Ruiz-Sinoga, J. D.: SQI: Development index and application for two contrasting mediterranean landscapes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15889, https://doi.org/10.5194/egusphere-egu21-15889, 2021.

How climate change will affect soil functioning is a major concern, especially in Mediterranean agrosystems, where, according to climate change projections, the occurrence of extreme temperatures and drought events will be increased. The main objective of our experiment was to evaluate the effect of land management (tillage system) on soil resilience against a simulated dry-rewetting cycle. Soil samples were collected from an in-situ field experiment established in 2008 in the Guadalquivir Valley, where conservation agriculture practices have been tested. Three different land management practices under a typical Mediterranean wheat-legume rotation system were compared: 1) traditional tillage (TT), 2) minimum tillage (MT) and 3) no-tillage (NT). Following our hypothesis, conservation agriculture practices (reduced tillage and no-tillage) may allow a more mature soil microbial community by reducing soil perturbation, and this would result in higher resistance of soil functioning against drought periods. Soil enzyme activities (β-glucosidase, phosphatase, acetylglucosaminidase, aminopeptidase, and dehydrogenase activities), microbial functional diversity (Microresp method), and soil DNA concentration (as an index of microbial biomass) were analyzed in a base-line sampling. Afterwards, a dry-rewetting cycle was simulated under controlled conditions. 8 subsamples of 50g from each soil sample were hydrated to reach 70% of each soil water holding capacity (WHC) and kept in those conditions for a pre-incubation period of 15 days. After this period, half of the replicates were let dry for 12 days (drought), while the others were maintained at 70% WFC (controls). Finally, all replicates were rehydrated again to the initial water content during a 14 days rewetting period. During this cycle, soil respiration rates were periodically measured to study the evolution of soil microbial activity. Our results showed that initial respiration rates were slightly higher in MT compared to NT (p<0.1), likely due to higher organic C and N content in the MT soils. Drought extremely reduced respiration rates in the three treatments, but the results did not show a clear pattern among treatments. During the rewetting period, respiration rates were significantly higher in drought samples in comparison with the controls, while no significant differences were found for the land management treatments. Besides, land management practices did not have a significant effect on soil DNA concentration, functional diversity of the microbial community, or enzyme activities. To conclude, the absence of a clear effect of land management practices on soil resilience to drought may be due to the experimental conditions. An in-situ experiment will allow us to determine if tillage reduction enhances soil resilience to moisture stress.

How to cite: Morales, L., Domínguez, M. T., Herrador, M. B., Madejón, E., and Fernández-Boy, E.: Effect of conservation agriculture practices on the resilience of Mediterranean soils to the predicted seasonal drought events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7994, https://doi.org/10.5194/egusphere-egu21-7994, 2021.

Steep slope viticulture is a common practice in the Mediterranean basin offering landscapes of considerable environmental and socio-economic value. However, these agricultural systems are very fragile. One of the main problems is soil erosion due to extreme rainfall, both for drop splash and water accumulation. This may cause a progressive reduction in soil fertility and the occurrence of instabilities and land degradation phenomena. To worsen this condition there is the soil compaction by mechanization and the intensification of severe weather events due to climate change (Tarolli and Straffelini, 2020).

Sustainable farming techniques may provide innovative solutions to reduce the risk of soil erosion. A virtuous approach involves the use of herbaceous coverings between the rows of vines, for many reasons. They provide active protection from the kinetic energy of water droplets; reduce the amount of water flowing on the surface positively affecting the infiltration capacity of the soil; improve ecosystem services in the vineyard.

This work aims to evaluate the effectiveness of different types of grass cover in terms of erosion and runoff generation in steep slope viticulture. The research is part of the SOiLUTION SYSTEM project (www.soilutionsystem.com) within the EU Rural Development Programme (Programma di Sviluppo Rurale per il Veneto 2014-2020); it is proposed to identify an integrated system of environmentally and economically sustainable interventions to reduce the risk of erosion and improve soil management in the terraced area of Soave (Veneto region), one of the two Italian GHIAS-FAO site. In particular, we have set up an experimental vineyard, where different managements are being tested, one for each inter-row of equal size and slope. Downstream of each of them, a water/sediment trap has been developed, obtaining continuous measurements of water volume and sediment concentration over two years. In this way, it is possible to compare the measures understanding the propensity of managements to generate runoff and soil erosion.

Specifically, many types of managements have been evaluated. (1) Continuous tillage, or a bare soil row; (2) Reference, a row where the farm's traditional grass cover is proposed; (3) Nectariferous, or a mix of herbaceous species capable of attracting insects and thus increasing biodiversity in the row; (3) Single tillage, or a row tilled once a year; (4) Native, or a row sown with native species of the place where the vineyard is located.

In combination with in-field experiments, an analysis was carried out on remote sensing data. The evolution of high-tech in topography permits low-cost tools and methodology to create high-resolution Digital Terrain Models (DTMs). For this purpose, we used a RPAS (Remotely Piloted Aircraft Systems) paired with Structure from Motion technique (RPAS-SfM). 3D reconstruction provides detailed knowledge of the terrain features, offering interesting insight to understand the processes that took place in the vineyard. The integrated implementation of in-field measures with remote sensing data opens new opportunities in runoff and soil erosion understanding, providing stakeholders with useful guidelines for sustainable management.

Tarolli, P., & Straffelini, E. (2020). Agriculture in Hilly and Mountainous Landscapes: Threats, Monitoring and Sustainable Management. Geography and Sustainability, 1 (1) (2020), pp. 70-76. https://doi.org/10.1016/j.geosus.2020.03.003

How to cite: Straffelini, E., Otto, S., Pijl, A., Marchesini, E., Gottardi, S., Tormen, N., Pitacco, A., Tezza, L., and Tarolli, P.: The role of inter-row grass cover in steep viticulture: understanding soil erosion combining in-field observation and remote sensing, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2158, https://doi.org/10.5194/egusphere-egu21-2158, 2021.

Maintenance of ground cover vegetation in olive orchards has been shown to reduce soil and runoff losses as compared to bare soil. However, extrapolation of its impact at hillslope scale under different conditions still challenging for several reasons. One is the limited duration of available experiments, usually shorter than 3 years, which can´t capture the annual variability in precipitation typical of Mediterranean type of climate. A second reason is the small scale in which many experiments are carried out, which do not capture all the relevant erosion processes at hillslope scale. A third reason, hardly discussed, is the use of the runoff plots that limits traffic resulting in conditions that might not be fully representative of actual orchards.

For evaluating the effect of temporary cover crops on water erosion processes in olives at hillslope scale, runoff and soil losses have been monitored from 2008 to 2019 in La Conchuela. This is an olive farm located in Southern Spain, where average annual precipitation is 655 mm, on Typic Haploxerert (clay content > 50%). Six runoff plots (14x24 m) delimited by steel beams on concrete foundation were established in a 13.4 % slope, containing 3 rows of 4 trees. This allows normal farm operations. Since 2008-2009, two soil management systems, conventional tillage (CT) and temporary cover crops (CC), were tested. In the two CT plots ground vegetation was controlled by 2-3chisel ploughing passes during the year. CC in the other four plots consisted of sowing manually in mid Fall a grass or a mix with grasses every 1 to 3 years without disturbing the soil surface, been mowed in early Spring. The aim of this cover crop was to be grown up spontaneously from seed produced the previous year. Weeds along the tree rows are controlled by herbicides in both cases.

No significant differences were detected (p < 0.05) for the whole period, although CC showed lower runoff and soil losses values. Runoff data ranged from 157.7 ± 61.2 to 144.5 ± 46.4 mm, and soil losses varied from 24.3 ± 9.1 to 16.4 ± 7.0 t·ha^-1 at the CT and CC treatments respectively. The lack of statistical differences can be explained by the large variability recorded in the measurements at the six plots, especially at the CC due to the specific weather and traffic conditions. Our experiment shows how in a crop, olives, subject to intense traffic during the harvesting season (happening in late fall or early winter, rainy season) and in an orchard on heavy soils, maintenance of a good cover crop is challenging in many years. Our results call for caution when extrapolating the benefits of cover crops in olives from the experimental plots to real world conditions. It also highlights the need for improved soil management under these conditions (e.g. controlled traffic, combination with inert mulch, …) to improve soil and water conservation in intensively cultivated olive orchards in heavy soils.

How to cite: Gomez, J. A. and Guzman, G.: Long-term evaluation of cover crops on soil and runoff losses under trafficked conditions in olive orchards, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-606, https://doi.org/10.5194/egusphere-egu21-606, 2021.

In Portugal, grain corn is the main cereal produced, comprising 56% of total cereal yield. It is grown in intensive monoculture cropping systems that may have negative effects on soil quality, affecting long-term fertility and productivity, and therefore the sustainability of production. A promising management practice to mitigate soil degradation is to grow a cover crop during the usual fallow period. This study examined in which extend six species of legume cover crops (forage pea (pisum sativum L), yellow lupin (lupinus luteus), crimson clover (trifolium incarnatum), balansa clover (trifolium michelianum), persian clover (trifolium suaveolens), and arrowleaf clover (trifolium vesiculosum) are suitable to mitigate soil threats in grain corn systems specifically in the Mediterranean region. Specific objectives were to identify the effectiveness of the legume 6 species in improving soil fertility (i.e., soil organic matter content), mitigating nutrient leaching, nutrient recycling, and weed control. The study was performed in the lower Mondego valley in central Portugal. It covered two autumn to spring periods of cover crop cultivation, and assessed changes in soil fertility, dry biomass yield of legumes and weeds, and their associated nutrient content (total nitrogen-phosphorus-potassium).

In general, the six legume cover crops (LCC) species showed good adaptation to Mediterranean conditions, yielding large amounts of biomass (up to 8 ton/ha for clovers species). At the short term, LCC incorporation into the soil had no clear effect in soil organic matter content. The median uptake of NPK macronutrients for all species was high respectively 176-20-172 kg/ha, due to their generally high biomass production, highlighting their great potential to mitigate nutrient leaching. The capacity of the LCC to provide green manure services enabled a median reduction of 40% of N, 60% of P, and 100% of K supplied by mineral fertilizers necessary to attain a corn grain yield of 12t/ha. LCC showed a good effectiveness in weeds control, although only in the second year of the study. Three clover species (crimson, balansa, arrowleaf) performed best in terms of weed control maintaining weed production below 0.5 ton/ha, vs 3-4 ton/ha in control plots, due to early establishment and/or high biomass production in later growth stages, and avoiding the first application of herbicide in pre-emergent herbicide for grain corn cultivation.

How to cite: Boulet, A. K., Alarcão, C., Ferreira, C., Veiga, A., Campos, L., Ferreira, A., and Hessel, R.: Introduction of legume cover crops practice in intensive grain corn crop system to mitigate soil threats in the Mediterranean region, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6199, https://doi.org/10.5194/egusphere-egu21-6199, 2021.

This paper investigates the use of plant trait analysis on cover crop species, and the impact selected species had on soil chemistry in a Spanish olive orchard. Farmers with hillside orchards in Spain frequently remove vegetation between tree rows due to concerns about water competition in the semi-arid environment. However, this increases the vulnerability of the soil to water erosion. Despite research showing that annual cover crops control soil loss, there has been little uptake of this form of management by farmers.

Ten species, native to southern Spain which had previously been used in cover crop experiments, and for which the seed was low cost, were assessed with plant trait analysis. Above and below ground traits, including specific leaf area, total biomass, root diameter and root volume, were examined to indicate the potential of the plants to reduce splash erosion, runoff and soil detachment. Four of the species were then selected and used in monocultures and mixes in an olive orchard set up in collaboration with CSIC in Cordoba. Soil moisture, rainfall, temperature and soil cover data was collected. Chemical analysis of plant and soil samples is to take place in January 2021.

Brachypodium distachyon, Calendula arvensis, Medicago sativa and Medicago truncatula had the most potential as cover crop species. In the field, the treatment with the greatest number of species (two grasses, one legume and one forb) had the highest mean soil cover at 78 ± 16%. It is hypothesised that the plots in which the greatest cover was established would show the greatest change in soil chemistry and that, where the legume was planted there will be higher nitrogen in the soil.

This presentation will outline the plant traits analysed, the outcomes of this analysis and the impact selected plants had on plant and soil chemistry in the field.

How to cite: Ripley, H., Stevens, C., and Quinton, J.: Plant trait analysis to determine effective annual cover crops for Spanish orchards, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-91, https://doi.org/10.5194/egusphere-egu21-91, 2021.

Low Density Polyethylene is the most applied plastic mulch in agriculture, for decreasing water evaporation, increasing soil temperature, or preventing weeds. Incomplete removal of polyethylene mulch causes plastic pollution in agricultural soils. In conventional agriculture the use of plastic mulch is combined with the use of pesticides. Little is known about the long term effects on soils of plastic debris accumulations in relation with pesticides residues.

We studied 18 parcels in vegetable farms, under organic or conventional management, where plastic mulch has been used for 5 to 20 years in Cartagena’s country side (SE Spain). We sampled soil at two depths: 0-10 cm and 10-30 cm. We compared the macro and micro plastic debris contents, the pesticides residue levels and the soil physiochemical properties between parcels. The ribosomal 16S and ITS DNA regions were sequenced to study shifts in bacterial and fungal communities, respectively. Soils under conventional management contained on average more than 6 different pesticides residues and soils in both managements contained on average 0.2±0.26 g/kg plastic debris. This study also showed how plastic and pesticides interact in soils and affect the microbial community. We identified the most sensitive groups which can act as bioindicators for plastic and pesticide pollution in soils.

How to cite: Beriot, N., Zornoza, R., Zomer, P., Ozbolat, O., Lloret, E., Ortega, R., Miralles, I., Huerta Lwanga, E., and Geissen, V.: Plastic mulch in agriculture: the case of low density polyethylene and its interactions with pesticides and soil microbiota, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7408, https://doi.org/10.5194/egusphere-egu21-7408, 2021.

Predicting ephemeral gully (EG) location is essential for erosion modeling because it helps confine portions of the hillslope segment above locations that gully and channel soil loss processes dominate. In the Water Erosion Prediction Project (WEPP), the prediction of EG occurrence location influences the model results by shorting or expanding the flow path, which the hillslope erosion modeling relies on. This research aimed to analyze the sensitivity of EG locations prediction accuracy on WEPP model output within the framework of the Daily Erosion Project (DEP) at the regional scale. DEP is a near real-time estimator of precipitation, soil detachment, hillslope soil loss, and water runoff using WEPP as the erosion model. The above estimations are conducted on randomly selected and spatially distributed flowpaths, and the means are reported at the HUC12 watershed level. The flowpaths are identified based on Digital Elevation Model (DEM) grid cell and D8 connectivity to adjacent cells. A flow path starts at a cell such that all adjacent cells are at a lower elevation, that is, no other adjacent cell directs flow into it and ends when sufficient flow concentration and soil conditions occur that channel erosion processes dominate soil loss where usually EGs occurrence. In this research, the DEP flowpaths, down to and including ephemeral gully heads, were surveyed in 8 HUC12 watersheds distributed in 8 different Iowa MLRAs using high-resolution imagery in-field measurement. A grid order model was used as a method for EG location prediction. The sensitivity of accuracy of EG location prediction on WEPP/DEP soil detachment, hillslope soil loss, and water runoff model output was explored at hillslope, watershed, and regional spatial scale with both extreme rainfall events and yearly average erosion modeling. This research will allow a more clear understanding of EG prediction influence on erosion modeling and help improve the accuracy of erosion modeling by using WEPP / DEP.

How to cite: Wang, C., Cruse, R., Brian, G., Daryl, H., Kelly, T., and David, J.: Influence of Ephemeral Gully Location Prediction on Soil Erosion Estimation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1478, https://doi.org/10.5194/egusphere-egu21-1478, 2021.

The spreading use of remote techniques is in our daily life benefits to ease and/or speed up the acquisition and analysis of geographical data that can be meaningful for risk assessment or for taking decisions for prevention measures.

Here is presented one of the possible applications for the Unmanned Aerial Vehicle (UAV) acquisition, to evaluate the volume of eroded soils in a crop field due to washout after heavy rains. The case study is located North of Lausanne (Switzerland), in the village of Savigny. It is a crop field with a gentle slope where we can clearly see washout gullies appearing after rainfalls. A great number of small water streams disappeared for more intense agriculture which is the case here : According to topographical maps, a small stream was flowing in the past but disappeared  after 2004. It is interesting to see that after important rainfalls, gullies appear that could correspond to old small stream patterns. 

The data acquisition survey of October 30th, 2020 was done by means of a DJI Phantom 4 RTK flying at an altitude of about 20m and the Pix4d Capture planning mission application. To process the obtained 800 images, the new Pix4D Matic software was tested to get a fast dense point cloud with GSD ~1 cm accuracy, a DEM and an orthophoto. The dense point cloud was then analyzed with two compared methods to estimate the washout volumes, which are (1) inverse Sloping Local Base Level; and (2) Point cloud segmentation based on normal vectors and curvatures.

As a result, these two methods gave a first estimation of the eroded volume of around 15m3 over a surface of 9 hectares which corresponds to an erosion rate of 1,7m3/hectare. These remote and non-destructive techniques are fast and easy compared to conventional field surveys, and the data acquisition and processing could be automated. In conclusion, these techniques provide a relatively low-cost time-series datasets processing to monitor and quantify the ongoing gully erosion. 

Further investigation would be to keep recording the volume and erosion rate estimations after important rainfalls, when clear new gullies appear and to record in the meanwhile the rainfall intensity. This could help assess in a second step the relationship between the erosion rate and the rainfall intensity and control if this relation follows a power-law function. Such a study could also give some clues about the possible impact of climate changes on erosions in crop fields. 

How to cite: Charlotte, W., Tiggi, C., Marc-Henri, D., Li, F., and Michel, J.: Quantification of erosion rate in crop field gullies from point clouds with two different methods  : the case study of Savigny crop field (North of Lausanne, Switzerland) , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2613, https://doi.org/10.5194/egusphere-egu21-2613, 2021.

Soil erosion is an important threat in the high-quality development of the Loess Plateau of China, and Ephemeral Gully (EG) erosion is an important erosion type. Answering the distribution characteristics of EG at the regional scale is an important basis for EG control. The regional distribution of EG and the areas that still at high risk of EG development after the 'Grain for Green Project' since more than 20 years ago remain poorly understood. This study aimed to solve the above problems by using visual interpretation based on sub-meter Google Earth images in 137 systematically selected small watersheds in the Loess Plateau. The EG density, length, land use of the hillslope where each EG existed, and other parameters were obtained and analyzed using the GIS method. The spatial distribution of EG density, average length, and spatial correlation in the Loess Plateau was explored. The current EG distribution and key prevention areas in the Loess Plateau were identified. The results showed that: (1) EGs were found in 46 surveyed watersheds accounting for 33.6% of the total watershed number, with an EG density average value of 3.41km/km² and maximum value of 21.92 km/km². The average number of EG was 60.32/km². EG length was mainly distributed in 20 ~ 60 m, with an average length of 63.31 m; The critical slope length of EGs was mainly 40 ~ 60 m, with an average 56.20 m. (2) The watersheds with EGs were mainly located in the north-central, the west, and northwest of the Loess Plateau. EG erosion is extremely strong in loess hilly and gully region, and moderate in loess plateau gully region.(3) 38.3% of EG was distributed in cropland; 35.3% distributed in grassland; 22.8% distributed in forest land. After the 'Grain for Green Project', the EGs that were still distributed on cropland were a more important threat to soil erosion and need better prevention efforts. EGs located on cropland were still widely distributed in many areas of Loess Plateau, such as the northwest of Yan 'an City in the middle and upper reaches of Beiluo River, Suide and Luliang in the lower reaches of Wuding River, at the junction of Dingxi and Huining and in Qingyang area. This research would help in a more reasonable distribution of erosion control practices in the Loess Plateau.

How to cite: Zhong, Y., Wang, C., Pang, G., Yang, Q., Guo, Z., Liu, X., and Su, J.: Spatial Distribution and Key Prevention Areas of Ephemeral Gully under the 'Grain for Green Project' in Loess Plateau, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3676, https://doi.org/10.5194/egusphere-egu21-3676, 2021.

Gully rehabilitation is often applied as part of catchment management aimed at reducing downstream sediment yields, yet the observed responses globally are variable. In the semi-arid tropics, there is limited data available to evaluate the performance of individual rehabilitation measures. This study investigated the effects of several low-cost gully rehabilitation strategies on sediment yields and vegetation establishment, in a savanna rangeland, north-east Queensland, Australia, over an eight-year period. Four gullies were monitored as untreated control gullies. Two gullies were subject to treatments aimed at: (i) reducing runoff to gully head cuts; (ii) increasing sediment trapping on gully floors; and (iii) increasing vegetation cover on gully walls and floors. Vegetation was monitored in nine gullies under long-term grazing exclosure as an additional reference to measure vegetation recovery. A runoff diversion structure reduced headcut erosion from 4.3 m² y^-1 to 1.2 m² y^-1. Total sediment yields were substantially lower in gullies treated with small porous check dams and cattle exclusion fencing, with mean total sediment yields reduced by 0.3-2.4 t ha y^-1. These treatments, however, had negligible effect on gully fine sediment (silt and clay) yields. While sediment deposited behind porous check dams was found to contain much less fine silt and clay than parent material, it contained several times that measured in untreated gullies. Organic matter and fine material deposited behind porous check dams were sufficient to trap seeds and initiate vegetation re-establishment on the gully floor, including native perennial tussock grasses and woody trees and shrubs. In this water-limited landscape, long-term rehabilitation will be strongly influenced by prevailing climatic conditions, with periods of recovery following wetter periods, and regression during extended dry periods. Understanding linkages between rehabilitation measures, their hydrologic, hydraulic and vegetation effects and gully sediment yields is important to defining the conditions for their success.

How to cite: Koci, J., Wilkinson, S., Hawdon, A., Kinsey-Henderson, A., Bartley, R., and Goodwin, N.: Effects of low-cost rehabilitation measures on gully sediment yields and vegetation in a savanna rangeland , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3742, https://doi.org/10.5194/egusphere-egu21-3742, 2021.

Soil erosion by water is a frequent soil degradation process in rangelands of SW Spain. The two main erosive processes in these areas are sheetwash erosion in hillslopes and gully erosion due to concentrated flow in valley bottoms. Land use changes and overgrazing play a key role in the genesis and development of gullies and gully erosion is a frequent process with negative consequences at the valley bottoms of these landscapes.

The development of new techniques allows monitoring of gully dynamics with an increase at spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland with a savannah-like vegetation cover that was partially restored in February 2017. Restoration activities included check dams (gabion weirs and fascines) and livestock exclosure by fencing. The objectives of this study were: (1) to analyze the effectiveness of the restoration measures, (2) to study erosion and deposition dynamics before and after the restoration activities, (3) to examine the role of micro-morphology on the observed topographic changes and (4) to compare the current and recent channel dynamics with previous studies conducted in the same study area through different methods and spatio-temporal scales, quantifying medium-term changes. Topographic changes were estimated using multi-temporal high-resolution DEMs produced using Structure-from-Motion (SfM) photogrammetry and aerial images acquired by a fixed-wing Unmanned Aerial Vehicle (UAV). DEMs and orthophotographs with a Ground Sampling Distance of 0.02 m were produced by means of SfM photogrammetric techniques. The average Root Mean Square Error (RMSE) estimated during the SfM processing was 0.03 m.

The performance of the restoration activities was satisfactory to control gully erosion. Check dams were effective favoring sediment deposition and reducing lateral bank erosion. Nevertheless, erosion was observed immediately downstream in 9% of the check dams. Livestock exclosure in the most degraded area promoted the stabilization of bank headcuts and revegetation. The sediments retained behind check dams reduced the longitudinal slope gradient of the channel bed and established a positive feedback mechanism for channel revegetation.

Keywords: gully erosion, restoration, topographic change, UAV+SfM, rangeland.

How to cite: Alfonso-Torreño, A., Gómez-Gutiérrez, Á., and Schnabel, S.: Spatio-temporal dynamics of erosion and deposition in a partially restored valley-bottom gully, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6378, https://doi.org/10.5194/egusphere-egu21-6378, 2021.

Lake Abaya and Lake Chamo are located within the rift valley that cuts across eastern Ethiopia. Severe soil erosion, predominantly gully erosion in the midlands and highlands, and flash flooding along rivers in the lowlands resulted in sediment and nutrient accumulation in the rift lakes. In this study, conducted in four river catchments on the Western border of the Abaya-Chamo rift, an inventory of gully channels is made and factors controlling the location of gullies are analysed. The inventory, which was prepared using Google Earth imagery and field surveys, consists of 7336 gullies over a study area of 1050 km², resulting in a high average gully density (1.56 km.km^-²) with specifically high densities (3.74 km.km^-²)  in the Northern Shafé river catchment. Of all mapped gullies, 56% show signs of active erosion (i.e. mostly bare gully walls and bed, and/or fresh sediments deposited in the lower parts of the gully). In order to reduce the effects of gully erosion, it is vital to understand the factors controlling gully initiation and locations most susceptible to develop new gullies. Instead of using gully head, which due to head cut retreat might not be representative of the characteristics of the gully initiation point, a slope-area threshold (SA) is used to identify the most probable gully initiation point along existing gullies. The spatial susceptibility of these sites to gully initiation is then modelled using the frequency ratio and logistic regression methods using a set of 15 geo-environmental variables related to topography, soil texture, geology, rivers, knickpoints and land cover, as potential controlling factors. Active and inactive gullies are modelled separately. Slope, type of lithology, location of knickpoint rejuvenating the landscape through channel incision, distance from roads and mean annual rainfall are identified as very important controlling factors of gully initiation sites. The most susceptible gully erosion areas are observed in the steep midland, where limited population is living, and bare land and rangeland is dominant. The results show that the models are reliable and have a good prediction performance of gully initiation when using an independent validation dataset. The produced gully susceptibility maps highlight locations where soil and water conservation or other sustainable planning actions are required. Such maps are also needed to estimate the long-term contribution of gullies to the sediments delivered to the Abaya-Chamo Lakes.

How to cite: Belayneh, L., Dewitte, O., Gulie, G., Poesen, J., and Kervyn, M.: Spatial modelling of gully initiation in the Abaya-Chamo lakes catchments, southern Ethiopia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13060, https://doi.org/10.5194/egusphere-egu21-13060, 2021.

Land degradation is a global concern posing significant threat to sustainable development. One of its major aspects is soil erosion, which is recognised as one of the critical geomorphic processes controlling sediment budget and landscape evolution. Natural rate of soil erosion is exacerbated due to anthropogenic activities that may lead to soil infertility. Therefore, assessment of soil erosion at basin scale is needed to understand its spatial pattern so as to effectively plan for soil conservation. This study focuses on Parbati river basin, a major north flowing cratonic river and a tributary of river Chambal to identify erosion prone areas using RUSLE model. Soil erodibility (K), Rainfall erosivity (R), and Topographic (LS) factors were derived from National Bureau of Soil Survey and Land Use Planning, Nagpur (NBSS-LUP) soil maps, India Meteorological Department (IMD) datasets, and SRTM30m DEM, respectively in GIS environment. The crop management (C) and support practice (P) factors were calculated by assigning appropriate values to Land use /land cover (LULC) classes derived by random forest based supervised classification of Sentinel-2 level-1C satellite remote sensing data in Google Earth Engine platform. High and very high soil erosion were observed in NE and NW parts of the basin, respectively, which may be attributed to the presence of barren land, fallow areas and rugged topography. The result reveals that annual rate of soil loss for the Parbati river basin is ~319 tons/ha/yr (with the mean of 1.2 tons/ha/yr). Lowest rate of soil loss (i.e. ~36 tons/ha/yr with mean of 0.22 tons/ha/yr) has been observed in the open forest class whereas highest rate of soil loss (i.e. ~316 tons/ha/yr with mean of 32.08 tons/ha/yr) have been observed in gullied area class. The study indicates that gullied areas are contributing most to the high soil erosion rate in the basin. Further, the rate of soil loss in the gullied areas is much higher than the permissible value of 4.5–11 tons/ha/yr recognized for India. The study helps in understanding spatial pattern of soil loss in the study area and is therefore useful in identifying and prioritising erosion prone areas so as to plan for their conservation.

How to cite: Kumar, R., Deshmukh, B., and Sathunuri, K.: RUSLE Model based Assessment of Soil Erosion in Parbati River Basin, Central India using Google Earth Engine and GIS, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1524, https://doi.org/10.5194/egusphere-egu21-1524, 2021.

【Objective】Rock fragments (>2mm diameter) are an important component of soil, and its presence has a significant impact on soil erosion and sediment yield. So it is essential to take into full account content of the rock fragments for accurate calculation of soil erodibility factor (K). 【Method】In this paper, based on the data available of the content of rock fragments and classes of soil texture with a resolution of 30 arc-second, influence of the content of rock fragments, including rock fragments in the soil profile (RFP) and gravels on the surface of the soil (SC), on K was assessed at a global scale, using the equation (Brakensiek, 1986) of the relationship between saturated hydraulic conductivity and grade of soil permeability, and the equation (Poesen) of soil erodibility attenuation under a rock fragment cover. 【Result】Results show: (1) The existence of rock fragments in the soil increased K by 4.43% and soil permeability by 5.68% on average in grade and lowering soil saturated hydraulic conductivity by 11.57% by reducing water infiltration rate of the soil and increasing surface runoff. The gravels on the surface of the mountain land and desert/gobi reduced K by 18.7% by protecting the soil from splashing of rain drops and scrubbing of runoff; so once the content of rock fragments in the soil profile and gravels on the surface of the land are taken into account in calculation, soil K may be 5.52% lower; (2)In the areas dominated with the effect of rock fragments, about 62.7% of the global land area, soil K decreased by 0.0091( t•hm²•h)•( hm^-2•MJ^-1•mm^-1) on average, while in the area affected mainly by rock fragments in profile, about 31.1% of the global land area, soil K increased by 0.0019( t•hm²•h)•( hm^-2•MJ^-1•mm^-1); and (3)The joint effect of rock fragments in profile and gravels on the surface reduced the soil erosion rate by 11.8% in the 6 sample areas. 【Conclusion】 The presence of RFP increases soil K while the presence of SC does reversely. The joint effect of the two leads to decrease in soil erosion. In plotting regional soil erosion maps, it is essential to take both of the two into account so as to improve accuracy of the mapping.

How to cite: Yang, M., Yang, Q., Zhang, K., Li, Y., Wang, C., and Pang, G.: Effects of Content of Soil Rock Fragments on Calculating of Soil Erodibility, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1976, https://doi.org/10.5194/egusphere-egu21-1976, 2021.

The impact of climate change on future soil loss is commonly assessed with soil erosion models, which are potentially an important source of uncertainty. Here we propose a soil erosion model ensemble, with the aim to reduce the model uncertainty in climate change impact assessments. The model ensemble consisted of five continuous process-based soil erosion models that run at a daily time step, i.e. DHSVM, HSPF, INCA, MMF and SHETRAN. All models simulate detachment by raindrop impact (interrill erosion), detachment by runoff (rill erosion) and immediate deposition of sediment within the cell of its origin. The models were implemented in the SPHY hydrological model. The soil erosion model ensemble was applied in a semi-arid catchment in the southeast of Spain. We applied three future climate scenarios based on global mean temperature rise (+1.5, +2 and +3 ºC). Data from two contrasting regional climate models were used to assess how an increase and a decrease in extreme precipitation affect model uncertainty. Soil loss is projected to increase and decrease under climate change, mostly reflecting the change in extreme precipitation. Model uncertainty is found to increase with increasing slope, extreme precipitation and runoff, which reveals some inherent differences in model assumptions among the five models. Moreover, the model uncertainty increases in all climate change scenarios, independent on the projected change in annual precipitation and extreme precipitation. This supports the importance to consider model uncertainty through model ensembles of climate, hydrology, and soil erosion in climate change impact assessments.

This research was funded by ERDF/Spanish Ministry of Science, Innovation and Universities - State Research Agency (AEI) /Project CGL2017-84625-C2-1-R; State Program for Research, Development and Innovation Focused on the Challenges of Society.

How to cite: Eekhout, J., Millares-Valenzuela, A., Martínez-Salvador, A., García-Lorenzo, R., Pérez-Cutillas, P., Conesa-García, C., and de Vente, J.: A process-based soil erosion model ensemble to reduce model uncertainty in climate change impact assessments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2464, https://doi.org/10.5194/egusphere-egu21-2464, 2021.

Gully erosion is an important land degradation process, threatening soil and water resources worldwide. However, in contrast to sheet and rill erosion, our ability to simulate and predict gully erosion remains limited, especially at the continental scale. Nevertheless, such models are essential for the development of suitable land management strategies, but also to better quantify the role of gully erosion in continental sediment budgets. We aim to bridge this gap by developing a first spatially explicit and process-oriented model that simulates average gully erosion rates at the continental scale of Africa.

We are developing a model that predicts the likelihood of gully head occurrence by means of the Curve Number (CN) method. This model will allow to simulate the spatial patterns of gully density at high resolution (30m) based on the physical principles that control the gully erosion process by using GIS and spatial data sources that are available at the continental scale. To calibrate and validate this model, we make use of an extensive database of 44 000 gully heads mapped over 1680 sites that are randomly distributed across Africa. The exact location of all gully heads was manually mapped by trained experts, using high resolution optical imagery available in Google Earth. This allows to extract very detailed information at the level of the gully head, such as the local slope and the area draining to the gully.

Based on an explorative analysis on a subset of this dataset we found that the CN method does not directly allow to make reliable predictions on gully head occurrence within a pixel. Although land use and land cover seem to play an important role (with gully heads being clearly located in erosion-prone land use classes), the hydrological soil groups (HSGs) based on soil texture do not provide a clear relation between soils with high runoff risk and gully occurrence. A potential cause for this is likely that compensating soil effects occur: i.e. HSGs that produce low runoff volumes may be characterized by a lower soil cohesion, making them nonetheless prone to gullying. This may then cause the combination of HSG and land use to be an insignificant predictor of gully occurrence. Also uncertainties on the input data likely play an important role in this.

Overall, our results indicate that modelling gully densities using a process-oriented and spatially explicit method offers opportunities to better quantify this important land degradation process at the global scale. Nevertheless, a key challenge lies in accurately quantifying the importance of soil characteristics and especially in better understanding their relative contribution to runoff production and soil cohesion.

How to cite: De Geeter, S., Vanmaercke, M., Verstraeten, G., and Poesen, J.: Can we use the Curve Number approach to predict gully head occurrence at the continental scale of Africa?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2666, https://doi.org/10.5194/egusphere-egu21-2666, 2021.

In the Mediterranean semi-arid environment (e.g., in Southern Italy and Spain), headwaters are characterized by local factors, such as steep slopes, low drainage areas and heavy and short-duration rainstorms, which make the torrents prone to flash floods, soil erosion and landslides. The construction of check dams has contributed to mitigate the runoff and erosion rates, but the effectiveness of these structures has been rarely assessed. In these contexts, the availability of studies monitoring the mitigation effect of check dams on the hydrological response of torrents at the watershed scale over a long time could help developing new management strategies. To this aim, this study proposes an assessment of the multi-decadal runoff and erosion rates in two headwaters of torrents in Southern Italy, using a modeling approach. The first torrent (Vacale, 12.5 sq. km) is regulated by check dams built in ‘1950-1960, while the second torrent (Serra, 13.7 sq. km) is not regulated. Both catchments experienced an increase in forest cover up to the 70%, while the agricultural land decreased by about 30% of the total area after the construction of the control works until now. The hydrological response of the two headwaters has been simulated using the widely applied Hydrologic Modeling System (HEC-HMS) model for runoff and peak flow, coupled with the Modified Universal Soil Loss Equation (MUSLE) to model sediment yield. To this purpose, 10 heavy rainfall-runoff events occurred between 1956 and 1971 were modeled. The peak flows and sediment yields of the regulated watershed were compared with the corresponding simulations at the undisturbed torrent. To summarize the results of this modeling experience, the changes in land cover resulted in a noticeable decrease in flood peak discharge (on average -53%) in both torrents, while the torrent with check dams showed a significant reduction of eroded sediment for each event (on average -9%) compared to the unregulated headwater. These findings help supporting a better understanding on the impact of control works and land use changes on the hydrological responses of Mediterranean torrents, indicating the most effective strategy to mitigate flash flood hazards and heavy erosion risks in similar environmental contexts.

Acknowledgement: This research was funded by ERDF/Spanish Ministry of Science, Innovation and Universities-State Research Agency (AEI) /Project CGL2017-84625-C2-1-R; State Program for Research, Development and Innovation Focused on the Challenges of Society.

How to cite: Bombino, G., D'Agostino, D., Denisi, P., Labate, A., Perez Cutillas, P., Martinez Salvador, A., Zema, D. A., Zimbone, S. M., and Conesa Garcia, C.: Comparing the hydrological response of regulated vs. not regulated mountain torrents in the Mediterranean semi-arid environment: a case study in Southern Italy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2707, https://doi.org/10.5194/egusphere-egu21-2707, 2021.

Rainfall-induced shallow landslides characterize most of the geomorphological phenomena occurred in Liguria (North West Italy) in the last decades: high frequency is observed between the beginning of October and the end of April, reasonably correlated with the seasonal rainfall regime.Over the years, in national and international scientific papers, the thickness of the debris cover, the poor geotechnical characteristics of the soil, the sparse forest and shrub areas, the runoff water erosion along the slope surface were identified as landslide causal factors.However, an aspect that does not seem to be considered in Liguria Region is the causal relationship between wildfires and surface landslides.The wildfire determines a series of physical and chemical changes on the slope surface, first of all the wood and shrub cover reduction. The rapid change in land use determines an increase in the run-off and a consequent soil erosion evolving into landslides.This research aims to create a first basic statistics at regional scale among landslides and wildfire, crossing different databases and inventories, estimating a trend line both in the spatial and in the temporal domain.

How to cite: Terrone, M., Faccini, F., Paliaga, G., and Solimano, M.: Wildfire and shallows landslides: a first statistical description in Liguria (North-West Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3149, https://doi.org/10.5194/egusphere-egu21-3149, 2021.

Gully erosion is one of the most important erosion gully types in the Loess Plateau. Its generation and development seriously affect and destroy the ecological environment. Therefore, it is the premise of scientific management to make clear the spatial distribution of gully region scale. At present, scholars at home and abroad mainly focus on the spatial distribution of gully in a specific small watershed, and there are few reports on the regional scale. In view of this, this study, based on Google Earth sub meter image combined with GIS method, uses the means of manual visual interpretation to conduct sampling survey of gully in the Loess Plateau. A total of 137 sampling units were set up, and the area of each sampling unit was about 0.2 square kilometers. The results showed that: (1) there were 75 gullies in 54.7% of the survey units, with a total of 712 gullies. The sampling units with gullies were mainly located in the northeast of the Loess Plateau (yan'an-dongsheng area on both sides of the Shanxi Shaanxi Yellow River) and the middle of the Loess Plateau (the border area of Guyuan, Ningxia and Huining, Dingxi, Gansu), with an average gulley density of 3.32km/km² and a maximum of 19.94km/km²; (2) the grassland was the most gullied area The main land use types of gully development accounted for 40.03%, followed by cultivated land and forest land, accounting for 30.06% and 20.08% respectively, and 9.83% of gully development was in bare land, orchard and residential land, collectively referred to as other land; (3) the average values of gully width, length and distance from watershed were 7.76m, 69.81m and 79.19m, respectively, and the gully width was mainly distributed in 3-5M, accounting for 50% 39.6％。 The length of gully was mainly distributed in 30-70m, accounting for 46.3%. The distance between  and watershed was mainly 25-50m, accounting for 41.6%; (4)  existed most in sub region I of Loess Plateau (22.7%), followed by sub region III of Loess Plateau (20.0%), sub region V of Loess Plateau (12.0%) and sub region II of Loess Plateau (9.3%); (5) according to the existing erosion classification standards,  erosion intensity of Loess Plateau reached strong level No. The gully density and gully length show obvious spatial differentiation characteristics. The highest density area is in yan'an-dongsheng area on both sides of Shanxi Shaanxi Yellow River, and the gully length in this area is about 100m. This study will help to better understand the spatial distribution characteristics of  in the Loess Plateau, support  management in the Loess Plateau, and promote scientific decision-making of  control in the Loess Plateau.

How to cite: Su, J., Wang, C., Pang, G., Yang, Q., Liu, X., Guo, Z., and Zhong, Y.: Regional Scale Distribution of Gully in Loess Plateau Based on High Resolution Google Earth Satellite Imagery, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3698, https://doi.org/10.5194/egusphere-egu21-3698, 2021.

Introduction

Accelerated erosion by human activities leads to degradation of soil ecosystem services and aquatic environment. It is unavoidable issue in Japan because it holds many sloped agricultural lands. Tokoro river watershed, TRW, in eastern Hokkaido, Japan has unique climate characterized with the least precipitation in Japan and cold winter with little snow which induces soil freezing. Frozen subsoil forms impermeable layers to increase surface runoff in early spring. The objectives of this study were i) to understand the spatial and seasonal variation of water and sediment movement in TRW using Soil and Water Assessment Tool, SWAT which is a process-based hydrological model and ii) to evaluate the impact of agricultural activities, topography of agricultural lands, and runoff characteristics on soil erosion through identification of highly erosive areas and seasons based on the simulation output.

Materials and methods

Water and sediment movement in TRW was simulated from 2011/1/1 to 2015/12/31. SWAT calculates water and sediment movement processes using spatial and temporal information of topography, land use, soil, weather, and land management in watershed. TRW was delineated into 17 subbasins based on topographic information and further divided into 764 HRUs which had homogenous combination of slope class, soil type, and land use in each subbasin. On-land processes were calculated in each HRU. After water and sediment yield from HRUs were summed in each subbasin, stream routing processes were calculated. Model parameters were calibrated so that the estimated stream flow and sediment load at the outlet would fit the measurements. From the simulation by the calibrated model, outputs were extracted as follows: 1) Contribution to the gross sediment yield and erosion rate of each land use; 2) Erosion rate of each subbasin; 3) Erosion rate of whole watershed on each month; and 4) Surface runoff and percentage of surface runoff in water yield in each month.

Results and Discussions

Calibrated SWAT reproduced well the fluctuation of stream flow and sediment load at the outlet of TRW. Although the model underestimated sediment load during large flood events with the average estimation error of -16.1±5.4% on peak-discharge months, it showed satisfactory performance with coefficient of determination: R²=0.88, Nash-Sutcliffe efficiency coefficient: Ens=0.86, and percentage of bias: PBIAS=0.34% for monthly sediment load estimation. Agricultural lands which covered 17.6% of the watershed were considered as the primary sediment sources contributing to 68.5% of estimated gross sediment yield of the watershed. Spatial variation of estimated erosion rate showed high sediment yield in the middle- and down-stream area of TRW where agricultural activities were intensive, and higher sediment yield particularly in the area where more agricultural lands had steep slopes (more than 51 t km^-2 yr^-1). Monthly erosion rate estimation indicated that the most severe erosion occurred on March and April (6.9±1.4 and 7.3±1.9 t km^-2 mon^-1 respectively). On March, average percentage of surface runoff was estimated as 90.5±6.5%. Therefore, surface runoff in early snowmelt season when the frozen subsoil prevented infiltration was considered as an important driver of soil erosion.

How to cite: Mihara, K., Kuramochi, K., and Hatano, R.: Spatio-temporal analysis of soil erosion in Tokoro river watershed in eastern Hokkaido, Japan, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4036, https://doi.org/10.5194/egusphere-egu21-4036, 2021.

Wind erosion of arable soil is considered a risk factor for Austrian fields, but direct measurements of soil loss are not available until now. Despite this uncertainty, vegetated windbreaks have been established to minimize adverse wind impacts on arable land. The study addresses these questions: i) How relevant is wind erosion as a factor of soil degradation? ii) How important is the protective effect of vegetated windbreaks? iii) Are systematic patterns of spatial and temporal variability of wind erosion rates detectable in response to weather conditions? 

Two experimental fields adjacent to windbreaks were equipped with sediment traps, soil moisture sensors, and meteorological measurement equipment for microclimatic patterns. Sediment traps were arranged in high spatial resolution from next to the windbreak to a distance of ten times the windbreak height. Beginning in January 2020, the amount of trapped sediment was analyzed every three weeks. The highest wind erosion rates on bare soil were observed in June and July. For unprotected fields with bare soil, upscaled annual erosion rates were as high as 0.8 tons per hectare, and sediment trapped increased in a linear fashion with distance from the windbreak. Soil water content near the surface (5 cm depth) was three percent higher at a distance of two times the height of the windbreak than at a distance of six times the height. For the same respective distances from the windbreak, we observed 29 days of soil water contents below the wilting point compared with 60 days.

The preliminary outcomes confirmed the expected effects of windbreaks on soil erosion and microclimate in agricultural fields. Prospective results from multiple vegetation periods will be used in an upscaling approach to gain informations for the whole basin. That is meant to be done by a combination with a soil wind erosion model which was so far used for regional modelling of wind erosion susceptibility.

How to cite: Weninger, T., Scheper, S., King, N., Gartner, K., Kitzler, B., Lackoova, L., Strauss, P., and Michel, K.: Spatio-temporal effects of vegetated windbreaks on wind erosion and microclimate as basis for model development, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9182, https://doi.org/10.5194/egusphere-egu21-9182, 2021.

The characteristics (magnitude and timing) of individual rainfall erosivity (RE) events in Europe strongly control soil loss at timescales from the individual event to long term annual average. While annual averages of soil erosion encompass the long-term variability of the event-based drivers of soil erosion (soil condition, water kinetic energy, vegetation properties), they provide both little direct information on the timing of soil loss or capacity to fully understand future erosion. Across the spectrum of empirical to physically based process models, event-scale estimates of rainfall energy are vital. The (R)USLE EI₃₀ index is a popular description of the combined effect of rainfall kinetic energy and the maximum 30-minute intensity of a rainfall event on soil loss. Modelling RE from daily or event rainfall accumulation seeks to capture the intra-annual meteorological controls on the EI30 index, with the goal of utilising rainfall data with higher abundance (eg daily) than conventional but less common hyetograph data. To date, no systematic study has provided model parameter surfaces for Europe’s climatic regions and investigated their spatial configuration. For each of 74 relevant environmental strata (EnS) within 13 broader environmental zones, we calibrate and validate 5 power-law based models with monthly and annual parameter sets using the REDES dataset, composed of over 300,000 RE events from national gauge networks.

We demonstrate the applicability of delineated environmental strata for subsampling and modelling event rainfall erosivity with heterogeneous national gauge data coverage and extent. Power-law model fits with 12 individual monthly parameter sets outperformed annual models with periodic cosine functions. The power-law α and β parameters are generally correlated through space (r = 0.66) and follow the general European trend of long-term annual average RE, increasing from North-West to South-East. The average annual Nash-Sutcliffe model efficiency for all strata increased from 0.427 (max: 0.76, min: 0.21) to 0.437 when the top 1 percentile of events were removed, which contribute between 8 and 27% of the total RE per stratum. The prediction capacity was higher in autumn and winter than in spring and summer when rainfall holds generally higher unit kinetic energy. Average model efficiency per environmental zone depended on both the rainfall stochasticity and size of the national data sample within each stratum, highlighting the importance of ample data extents for predicting event rainfall erosivity in Europe.

How to cite: Matthews, F., Panagos, P., and Verstraeten, G.: Modelling event scale rainfall erosivity across European climate regions , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10087, https://doi.org/10.5194/egusphere-egu21-10087, 2021.

Fuzzy logic is often used for calculation and simulation of real environmental situations. Wind erosion can often be complex, and from various erosion situations it is one of the hardest to be calculated and exactly described. In our research, we based the structure of the fuzzy system on the soil loss of six soils with different mechanical compositions measured in wind channels. Measurement of soil loss in four wind speed ranges during soil channel testing of soils. During the wind tunnel analysis of the soils, the topsoil loss was measured in four wind speed ranges (I. 11,2-11,6 m/s; II. 12.5-13.3 m/s, III. 14.4-14.7 m/s, IV. 15.5-15.7 m/s) on six soils with different mechanical compositions (four sand and two clayey sand soil). The mathematical model programmed and built up in MATLAB, this mamdani type fuzzy evaluation system uses two input parameters wind speed and ErosionFactor. The mathematical model requests the soils mechanical composition and identifies it based on the USDA triangle diagram. Many mathematical methods applicable to fine tune a fuzzy system. We have chosen the method of exhaustive design to cover the whole parameter space. The mathematical model calculated the soil loss. Model runs were also performed with the SWEEP model according to the soils examined in the wind tunnel. Based on our results, we found that using our fuzzy mathematical model, we obtained estimated soil loss values similar to the SWEEP model compared to the soil loss measured in the wind tunnel. However, it should be noted that the USDA SWEEP model requires a much larger amount of data to estimate the extent of soil loss caused by a wind erosion damage event.

How to cite: Tatárvári, K. and Piros, A.: Fuzzy mathematical model for estimating wind erosion based on wind tunnel data, comparison of results with laboratory measured and SWEEP model results, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13701, https://doi.org/10.5194/egusphere-egu21-13701, 2021.

In erosion studies the behavior of rainfall is primordial, since rain is responsible for the first stage of the erosion process: the detachment of soil particles. The erosive potential of rainfall, erosivity, is considered in the universal soil loss equations (R)USLE family through the parameter R, or R factor. This factor is calculated from the rainfall erosivity index, which is the product of kinetic energy of the rain by the maximum intensity of the rain of 30 minutes of duration. As sub-hour rainfall data is not always available, there are in the literature a series of equations obtained from regression, which use monthly and annual rainfall and present a good estimate of erosivity for your study site. In Brazil, in addition to limitations regarding the temporal resolution of rainfall data, there are also spatial limitations. Monitoring stations are concentrated mostly in urbanized areas, usually near the coast. The other regions, such as agricultural and forest areas, are poorly monitored, and these areas are of great interest for monitoring erosion, not only because they are periodically exposed soil areas, but also because of the high rainfall rates that humid forests like Amazon have. MSWEP is a rainfall database that combines observed, satellite and reanalysis data. It has global coverage, temporal resolution of 3 hours, spatial 0.1º and data from 1979 to 2016. Databases like this have great potential to be used in areas such as Brazil, due to its spatial and temporal resolution. In this context, considering the relevance that the soil loss equations still present today, this work developed a rainfall erosivity database entitled REDB-BR (Rainfall Erosivity Database for Brazil). It provides the R factor in a 0.1º resolution grid, developed with 37 years of rainfall data from the MSWEP dataset. The R factor was calculated trough 73 erosivity index regression equations, which mostly uses the Modified Fournier Index (MFI), a relation between monthly precipitation and annual precipitation. Thiessen polygons were used in order to spatialize and define the areas of each equation. Over the Brazilian territory, the R factor ranges from 1.200 to 20.000 MJ mm ha-1 h-1 year-1, with the higher values in the North region, and the lowest values in the Northeast. The spatial patterns of erosivity are very similar to the climatic zones of Brazil. The R factor map takes advantage of MSWEP dataset and presents a spatial resolution very detailed to a country with continental scale such as Brazil. The database includes the equations shapefile and table, Thiessen Polygons shapefile and the R factor map in raster format, which allows more possibilities of application. The database can be accessed at <https://zenodo.org/record/4428308#.X_hxsOhKiUk>. We identified sudden changes in behavior between the delimited areas, which suggests a need for more regression equations in order to better represent the behavior of the erosivity in the Brazilian territory.

How to cite: Petry, I. and Mainardi Fan, F.: A Rainfall Erosivity database for Brazil from MSWEP rainfall dataset, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1432, https://doi.org/10.5194/egusphere-egu21-1432, 2021.

The soil splash phenomenon is the initial stage of the water erosion process. It occurs when a rain drop hits the soil surface and causes a few processes e.g. i) detachment of soil particles and their transport over different distances, ii) breakdown of soil aggregates, iii) surface runoff or iv) formation of a crusted surface.

The aim of the study was to carry out an analysis of the splash erosion in mineral soil in 4 variants of sample preparation: a) dry natural soil, b) wet natural soil, c) dry burnt soil, d) wet burnt soil.

In both cases (natural soil and soil modified with high temperature), full moistening was achieved by capillary rise. Fire simulation was carried out in several variants at varying temperature and duration. Variant that affected soil wettability to the greatest extent was selected for the splash analyses. "Natural" and "modified" wettability were measured using the water drop penetration time (WDPT) method. "Natural" wettability classified soil into the "wettable" group (WDPT < 5s), while the modification of the surface properties by high temperature changed the wettability group of the analyzed soil into "slightly to moderately repellent" (5 s > WDPT < 60s).

Each time, the soil material was placed in aluminum rings with an internal diameter of 36mm and a height of 10mm, and the surface was leveled without excessive compaction of the sample.

A single drop of distilled water with a diameter of 4.2 mm fell on the sample prepared in this way from a height of 1.5m. The drops were dosed with a peristaltic pump and reached the final velocity of 4.98 m/s.

Three synchronized Phantom Miro M310 cameras (Vision Research, USA) were used to register the splash phenomenon. The recorded films were used to analyze the splash phenomenon through measurements of the velocity, angle and distance of ejected particles.

A Scan3D UNIVERSE 10 MPiX structural light scanner (Smarttech 3d, Poland) was used to determine the magnitude of the surface deformation caused by the drops. The analyses made it possible to determine e.g. the depth, diameter, and volume of craters and the height of surrounding rims.

The analysis of the results showed significant differences in the size and dynamics of the emerging splash depending on the degree of soil wettability.

The study was partially funded by the National Science Centre, Poland, as part of project no. 2017/26/D/ST10/01026.

How to cite: Sochan, A., Mazur, R., Beczek, M., Ryżak, M., Polakowski, C., and Bieganowski, A.: The analysis of splash erosion depending on the degree of soil wettability - a preliminary study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14186, https://doi.org/10.5194/egusphere-egu21-14186, 2021.

Extreme meteorological events are important causes of environmental damages, particularly in mountain areas that can be heavily affected by destructive processes such as landslides and debris flows. From 27 and 30 October 2018, an extraordinary storm - named Vaia - hit Northeastern Italy. The Vaia storm triggered mass wasting processes, generated new slope instabilities, caused widespread windthrows, and damaged human infrastructure. This work aims at assessing the effect of the Vaia storm in the Liera Torrent basin (Venetian Dolomites, Italy), by building and comparing sediment source inventories before and after the Vaia storm. The Liera basin drains an area of 35 km² and elevation ranges between 976 and 3192 m a.s.l. The mapping and classification of the sediment sources have been carried out through the interpretation of high-resolution orthophotos and Digital Terrain Models (DTMs) derived from airborne LiDAR data (1-m resolution) acquired in 2015 and 2019. A topography-based index of sediment connectivity has been applied to characterize connectivity spatial patterns at catchment scale and identifying the sediment sources on the hillslopes effectively connected to the Liera torrent. A preliminary connectivity analysis showed that the upstream sector the catchment located in the Pale di San Martino plateau is not effectively connected to the lower Liera valley because of its karstic environment and debris originated from the highest portion of the relief are confined in a hollow. Thus the inventories have been limited to the medium and lower parts of the catchment considering an area of 20 km². Results indicated a total of 1650 sediment source areas after the Vaia event, with an areal increase of about 20% with respect to 2015 inventory, especially due to the development of landslide (843 in total for the 2019 inventory), expansion of the debris flow channel (257) and areas subject to surficial erosion (127). Other areas that have been identified encompass debris flow deposit (288), rock fall deposit (31), stream bank erosion (45), and other sediment source areas which need field survey to be properly classified (59). The analysis allowed: (1) obtaining reliable and detailed pre- and post- event sediment sources inventories, (2) assessing sediment connectivity at the catchment scale, which is fundamental for estimating the contribution of sediment sources and related transfer paths, (3) improving sediment dynamics understanding related to the Vaia storm in the study area. Future analysis will focus on field validation and residual sediment availability for the investigated areas. This study was carried out in the frame of the Interreg V-A Italy - Austria SedInOut project.

How to cite: Boretto, G., Crema, S., Marchi, L., Monegato, G., Arziliero, L., and Cavalli, M.: Assessing the effect of the Vaia storm on sediment source areas and connectivity storm in the Liera catchment (Dolomites), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7643, https://doi.org/10.5194/egusphere-egu21-7643, 2021.

Urbanization is a striking phenomenon, responsible for the development of cities as complex and highly dynamic systems. One of the most pressing issues in urban areas is water cycle management, which directly influences the availability and the quality of this resource. Urban streams are highly vulnerable to the impacts resulting from the increasing urbanization and they have often lost most of their pristine, natural character.

We hereby present the preliminary results of the multidisciplinary StrEams urbaN Ecological City plAnning (SENECA) project, which is not only but mainly devoted to characterizing the chemical features of stream waters and sediments of the Mugnone Creek (MC). MC is a typical example of an urban stream, crossing the city of Florence (Italy) and eventually discharging to the Arno River, that has suffered an intense denaturation due to the urban sprawl, such as several diversions, canalizations and rectifications, alterations of the stream bed and riparian habitat, widespread concrete revetment of the banks and burial of short stream tracts.

Different sites along the 17-km long MC were investigated for water and sediment geochemistry from upstream of the Florence urban area (“blank” sites) to the MC outlet (Cascine Park), passing through variably urban-impacted areas, including sites located along traffic-congested roads, close to the new tramway construction sites and under the railway line. Stream waters were sampled twice a year (June and December 2019 and 2020) to account for seasonal variability. Stream discharge at three representative points was simultaneously determined during water sampling to allow mass load calculations of contaminants. In details, major dissolved ions (Ca, Mg, Na, K, HCO₃, SO₄, Cl, NO₃) and reduced nitrogen (NH₄), trace elements (TEs: Sb, As, Cu, Zn, Cd, Co, Ba, Li, Pb, Ni) and microplastics (MPs) in stream sediments and waters of MC were determined. Major dissolved ions and NH₄ were analysed via acidimetric titration and IC. TEs were determined in both sediments and waters (0.45 μm filtered and unfiltered) by ICP-OES and ICP-MS, respectively. MPs (1 μm-5 mm) were identified in sediments and waters by HD binocular stereomicroscope.

Chemical composition (major element constituents) of water reflected both the seasonality and the progress of the water-rock interaction acting in MC from its spring toward the outlet. In addition, the pattern of abundances of Cu, Zn, Sb and Pb and especially their mass loads reflect the increasing anthropogenic impact on the water and sediments, even if is important to stress that the contents are within the limits defined by law, except for stream sediments at a few sites. For MPs, up to 10⁹ particles, coming mainly from the NW side of Florence, are estimated to be discharged daily to the Arno River during the winter season, much higher than creeks with similar urbanization contexts worldwide. Increasing data collection will make it possible to identify and better understand what type of sources and processes are responsible for the anthropogenic impacts in the MC and could help in better safeguarding the creek within the framework of the urban social-ecological systems of Florence.

How to cite: Bicocchi, G., Venturi, S., Monnanni, A., Martellini, T., Chelazzi, D., De Beni, E., Cincinelli, A., Morelli, G., Lattanzi, P., Fornasaro, S., Ciani, F., Costagliola, P., and Rimondi, V.: Anthropogenic impact on urban rivers: insights from the Mugnone Creek (Florence, Italy) waters and sediments characterization in the framework of the multidisciplinary SENECA project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7587, https://doi.org/10.5194/egusphere-egu21-7587, 2021.

Volcanic eruptions are natural disturbances capable of introducing large quantities of sediment into river systems as to upset the transport regime for several years. Such a disturbance can have a strong impact on the water and sediment flows and consequently on the transport capacity. Moreover, changes in morphological settings and land cover lead to an alteration of the sediment connectivity within the catchment. This study aims to investigate the changes of sediment connectivity in a catchment affected by an explosive volcanic eruption using the Index of Connectivity (IC) with a multi-temporal approach. Potential variations were analyzed at the catchment scale over a period of 6 years, before and after the eruption. The study area, located in southern Chile, is the Blanco Este River basin (39,6 km²), affected by the eruption of the Calbuco volcano (April 2015, total volume of sediment expelled of about 0,28 km³) which profoundly changed its vegetation cover, geomorphology and hydrology. IC analyses were based on low-resolution and freely available data (i.e., GDEM, Landsat 8 satellite images). Through supervised image classification and field data survey, a Manning's n coefficient for overland flow is derived as weighting factor (W) due to its suitability to represent the impedance to sediment flows in catchments characterized by land cover variations. Following the eruption, bare soil cover on the basin doubled (from 5% to 10% of total basin area). Consequently, the multi-temporal analysis results in an overall increase of IC with the median value ranges from -3,58 to -3,26 in pre-eruptive (2015) and first post-eruptive scenario (2016), respectively. The connectivity maps show that the higher IC values (i.e. range from -1,23 to 1,66) are persistently located in three areas: at the base of the volcanic dome, on the steepest slopes near the main channel and in a sub-basin on the right side of the catchment. Moreover, the Difference of IC (DoIC) among different scenarios highlighted the major variations. Such changes are found along the volcano slopes, in a flat area located in the upper part of the basin and along the lower valley of the Rio Blanco Este. The study proposes a useful methodology to evaluate the sediment connectivity, and its evolutionary trends, in environments affected volcanic eruptions starting from low-resolution data and field survey. These results may help to better define types, location and typologies of interventions to improve the river management approaches, considering the ongoing cascading processes. This research is funded by the Fondecyt 1200079 project.

How to cite: Andreoli, M., Martini, L., Cavalli, M., Iroumé, A., and Picco, L.: Impact of a volcanic eruption on the sediment connectivity of a Chilean river basin: the Calbuco study case, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5245, https://doi.org/10.5194/egusphere-egu21-5245, 2021.

Shrub encroachment of semiarid grasslands is influenced by connected runoff and erosion patterns that preferentially accumulate resources under vegetated patches (canopy microsites) and deplete interspaces. Soil loss from dryland hillslopes results when areas of bare ground become structurally and functionally connected through overland flow. Although these patterns have been well-described, uncertainty remains regarding how these feedbacks respond to restoration practices. This study compared the structure and hydrologic function of a shrub-encroached semiarid grassland treated five years prior with the herbicide, tebuthiuron, to that of an adjacent untreated grassland. Through a series of hydrologic experiments conducted at increasing spatial scales, vegetation and soil structural patterns were related to runoff and erosion responses. At a fine scale (0.5 m²), rainfall simulations (120 mm·h^-1 rainfall intensity; 45 min) showed herbicided shrub canopy microsites had greater infiltration capacities (105 and 71 mm·h^-1 terminal infiltration rates) and were less susceptible to splash-sheet erosion (3 and 26 g sediment yield) than untreated shrub canopy microsites, while interspaces were statistically comparable between study sites. Concentrated flow simulations at a coarse scale (~9 m²) revealed that gaps between the bases of vegetation (i.e. basal gaps) > 2 mwere positively related to both concentrated flow runoff (r = 0.72, p = 0.008) and sediment yield (r = 0.70, p = 0.012). Modeled hillslope-scale (50 m²) runoff and erosion (120 mm·h^-1 rainfall intensity; 45 min) indicated less soil loss in the tebuthiuron-treated site (1.78 Mg·ha^-1 tebuthiuron; 3.19 Mg·ha^-1 untreated), even though runoff was similar between sites. Our results suggest interspaces in shrub-encroached grasslands continue to be runoff sources following herbicide-induced shrub mortality and may be indicators of runoff responses at larger spatial scales. In contrast, sediment sources are limited post-treatment due to lesser sediment detachment from sheet-splash and concentrated flow processes. Reduced sediment supplies provide evidence that connectivity feedbacks that sustain a shrub-dominant ecological state may have been dampened post-treatment. Our study also highlights the utility of simple measures of structural connectivity, such as basal gaps, as an indicator of hillslope susceptibility to increased runoff and erosion.

How to cite: Johnson, J., Williams, J., Guertin, P., Archer, S., Heilman, P., Pierson, F., and Wei, H.: Structural, Hydrologic, and Sediment Connectivity in a Shrub-Encroached and Restored Semiarid Grassland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12904, https://doi.org/10.5194/egusphere-egu21-12904, 2021.

Currently, more and more researchers are recording increased pollution levels of chemicals in the environment of the Antarctic regions. It is noted that mostly concentrations are fixed for non-typical chemical contaminants of anthropogenic origin. These can be Heavy Metals (HM), Polycyclic Aromatic Hydrocarbons (PAH) or Polychlorinated Dibenzodioxins (PCDD). It is well known that these classes of substances have a negative impact on human health and are detrimental to the development of endemic species, as well as having carcinogenic and mutagenic effects.

The problem of pollution of Antarctic territories is especially relevant recently. As the scientific interest in these territories increases, the anthropogenic load on the fragile Antarctic ecosystems also increases in parallel. Chemical contaminants can enter the Antarctic continent in a variety of ways. Researchers bring large volumes of diesel fuel and other fossil fuels with them to heat research stations. This often results in oil spills and the discharge of contaminated wastewater into sub-Antarctic waters. Entry is also possible as a result of transboundary transfer of atmospheric emissions from the territories of Australia and South America, which are deposited in Antarctica.

In our investigation, 15 priority concentrations of PAHs and some heavy metals in the soils of Livingston Island (Antarctic Peninsula) were analyzed based on the analysis of soil samples obtained during the Bulgarian Antarctic Expedition. The data on PAH concentrations in soils allowed us to calculate different isomer ratios of aromatic hydrocarbons, which may indicate the nature of the origin of the contaminants.

Significant differences were recorded in the content of chemical contaminants between soils in the station area and its vicinity. Thus, for instance, the content of Naphthalene, Acenaphthene, Naphthalene and Pyrene in soils at “St. Kliment Ohridski” Station (Cryosol Toxic Transportic, WRB 2014) was at 170, 41, 38 and 60 µg/kg, respectively. While in the soils (Cryosoils Leptic Stagnic, Cryosol Leptic Ornitic Hypersceletic, Cryosol Turbic Gleyic, WRB 2014) around the station the content of similar PAHs were 53, 6, 20, and 21 µg/kg.

The highest concentration of heavy metals was also recorded in soils exposed to anthropogenic load. The concentrations of Cu, Pb, Zn, Cd, Ni and Cr were 22.6, 10.7, 75.7, 0.28, 10.1 and 5.25 µg/kg, respectively, in the soils of the Bulgarian station. For undisturbed Antarctic soils of Livingstone Island, heavy metal concentrations were significantly lower.

We also calculated some isomeric ratios of PAHs. The values of these ratios allowed us to reveal the nature of the origin of PAHs on Livingstone Island. In the samples collected at “St. Clement Ochridski” Station, the sources of PAHs are predominantly pyrogenic processes, combustion of liquid fossil fuels, and traffic source.

This work was supported by Russian Foundation for Basic Research, Projects No 18-04-00900, 19-54-18003 and 19-05-50107

How to cite: Nizamutdinov, T., Abakumov, E., Yaneva, R., and Zhiyanski, M.: Content of heavy metals and polycyclic aromatic hydrocarbons in soils of vicinities the Bulgarian Antarctic station "St. Kliment Ohridski", EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1801, https://doi.org/10.5194/egusphere-egu21-1801, 2021.

 The prediction of surface water resources in the Danjiangkou Basin is of great significance for the design of the water transfer plans for the South-to-North Water Diversion Project. However, it is difficult to obtain high-precision simulations for mid- and long-term hydrological forecasting. Based on the thought of extended streamflow prediction (ESP) and distributed hydrological models, this paper proposed a set of forecasting systems for predicting the annual surface water resources in the Danjiangkou Basin. Firstly,  the Wetspa model  was established to forecast the inflow of Danjiangkou reservoir. The Nash efficiency coefficients of the monthly average runoff during the calibration period (2006-2012) and verification period (2013-2016) were 0.97 and 0.95, respectively. Secondly, it was assumed that the rainfall of 2017 could be predicted by the rainfall forecasting model, then the rainfall process was obtained based on the ESP and the runoff process of the basin outlet was calculated through the Wetspa model. Finally, the predicted surface water resources of the Danjiangkou Basin in 2017 was 45.448 billion m³, and the actual surface water resources is 40.395 billion m³, with a relative error of 12.51%. The results showed that the prediction of surface water resources in Danjiangkou Basin based on ESP and distributed hydrological model could provide a certain reference for the design of water transfer plans of the Danjiangkou Reservoir.

Key words: Water resources prediction; ESP; Wetspa model; Nash coefficient

How to cite: Yuan, R., Cai, S., and Liao, W.: Prediction of Surface Water Resources in Danjiangkou Basin Based on ESP and Distributed Hydrological Model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2147, https://doi.org/10.5194/egusphere-egu21-2147, 2021.

Rock outcrops are common features of the karst ecosystem The bare rock rate is an important indicator for rocky desertification grades classification, and its accurate extraction can benefit for understanding the distribution characteristics of rock outcrops in desertification areas and the classification of rocky desertification grades. In order to explore the distribution pattern of surface bare rocks in the typical geomorphic environment of the Karst gabin basin, the Mengzi gabin basin was carried out as the research site. The combination of UAV shooting images and digital image processing technology were used, the characteristics of bare rock rate on the karst fault basin after vegetation restoration were shaped. Our results showed that digital image processing technology can be used for extraction of bare rock rate in Karst area, and the effective combination of UAV technology and digital image processing technology can quickly obtain bare rock rate data of typical landform in Karst gabin basins. After performing drone aerial photography on 26 typical landform information under different bare rock distribution conditions on the Mengzi gabin basin, the results of the image processing analysis showed that the bare rock rate is between 2.7%-28.9%. The research provide technical support for the assessment of the karst ecosystem degradation and the evaluation of the current status of rocky desertification in karst gabin basin

How to cite: Yin, Z. and Shan, Z.: Preliminary research on a method of outcrops extraction on Karst Gabin ecosystem based on digital image processing: the case of the Mengzi Gabin basin, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10513, https://doi.org/10.5194/egusphere-egu21-10513, 2021.

Here we present a 4200-year-old high-resolution peat core reconstruction from southern Patagonia. Our detailed carbon isotope (δ13C) record and testate amoeba-inferred water table depth reconstruction point to a progressive wetting of the peatland surface from 4200 to 1500 cal. yr BP, followed by a dry event at 1200-800 cal. yr BP and drier conditions since then. Superimposed on this trend are centennial-scale dips in δ13C values and water table depths that we associate with warm/dry spells. We interpret these shifts, which are akin to positive phases of the Southern Annual Mode (SAM), as reflecting century-scale changes in the Southern Westerly Wind belt during the late Holocene. Other records from southern South America and Tasmania have revealed synchronous changes in local vegetation and fire activity, strengthening our hypothesis. We know that millennial-scale shifts in the Westerly winds influence ocean upwelling in the Southern Ocean, with effects on global atmospheric carbon dioxide (CO2) concentrations. Our study, along with a few others, may help elucidate whether centennial-scale SAM-like shifts could also modulate the global carbon cycle via CO2 degassing from the deep ocean. This is important because instrumental and reanalysis records indicate strengthening and poleward contraction indicate a positive phase of the SAM since the late twentieth century.

How to cite: Loisel, J. and Sarna, K.: Peat-based record from southern Patagonia shows centennial-scale variability since 4.2 ka, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7993, https://doi.org/10.5194/egusphere-egu21-7993, 2021.

Open-pit mining for bitumen extraction generates considerable volumes of dust in northern Alberta. This area contains abundant peatlands, some of which are ombrotrophic bogs that are exclusively fed by atmospheric inputs. The most reactive mineral phases of dust deposited on these bogs can potentially dissolve in their surface waters because of the low pH and abundance of organic acids. Thus, peat bog surface waters could be used as unique monitors, to determine the chemical reactivity and dissolution characteristics of atmospheric dusts in industrial areas. The main goal of this study is to determine whether the elevated rates of dust deposition to peat bogs near bitumen mines have led to greater concentrations of trace elements (TEs) in the surface waters. To achieve this goal, it is essential to ensure that the TEs being measured in surface waters represent dust dissolution only and are not influenced by other element sources such as groundwaters or surface runoff.
Peat bog surface waters were collected in the autumn of 2019 from four peatlands near industry and a control site located more than 260 km upwind. Concentrations of TEs were determined in the dissolved fraction (i.e. filtered through a 0.45 μm membrane) using an ICP-MS. Surface waters near industry have elevated concentrations of Li, Fe, Mn, Ni, Y, selected REE (Tm, Dy, Yb, Sm) and Pb at 3 out of 4 sites, relative to the control location (UTK). Most of the elements are enriched 2x when compared to control site (UTK), but only Li, Mn, and Rb show enrichments >1Ox. At JPH4, the site closest to industry (12 km from the mid-point between the two central bitumen upgraders), a vegetation survey indicates that this peatland includes both ombrotrophic and minerotrophic zones, and this was confirmed by the pH and concentrations of major ions in the surface waters. At McK, the site next closest to industry (25 km), electrical conductivity as well as concentrations of chloride, Na, and K, all increase with distance toward the highway which is evidence of road salt runoff. Thus, at these two sites nearest industry, the TE concentrations in surface waters are supplied not only from airborne dusts, but contributions from groundwaters and road salt must also be considered. In contrast, the surface waters from the McM (49 km) and ANZ (69 km) sites are ombrotrophic, and elevated concentration of TEs in these samples can be attributed exclusively to dust dissolution.
The elevated concentrations of lithophile TEs in the dissolved fraction includes those which are
mobile in surficial environments (e.g. Li and Sr), but also those which are immobile (e.g. Y and the lanthanides). Elevated concentrations of the former are not surprising, but elevated concentrations of the latter are puzzling, given that they tend to be hosted within stable mineral phases that are resistant to chemical weathering. Size-resolved TE analyses of the dissolved fraction using AF4-ICP-MS will be used to distinguish between colloidal forms and ionic species, to differentiate inputs of nano-dusts from mineral dissolution in bog waters.

How to cite: Butt, S., Shotyk, W., Barraza, F., Chen, N., Cuss, C., Frost, L., Grant-Weaver, I., Javed, M., Noernberg, T., Oleksandrenko, A., and Pei, L.: Trace elements in peat bog surface waters as indicators of the dissolution of atmospheric dusts from open-pit bitumen mines, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1430, https://doi.org/10.5194/egusphere-egu21-1430, 2021.

Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are potentially proxies of changes in natural and human activities during the past century. It is important to identify historical BC sources and differentiate human activities contribution to BC in the environment. In this study, a 30 cm peat profile from the Jiadengyu (JDY) peatland in Altay Mountain was dated by the ¹³⁷Cs and ²¹⁰Pb methods. BC, total PAHs content and δ¹³C_BC in JDY peat were tested. The results showed that the TOC, BC and PAHS contents in JDY peat core were 17.09 ~ 47.16%, 1.14 ~ 67.138 mg/g and 260.58 ~ 950.98 ng/g, respectively. The value of δ¹³C_BC ranged -31.5‰ ~ -27.43‰, with an average of -30.52‰. The range of total PAHs concentrations in JDY peat core were between 260.59 ng/g and 950.98 ng/g. The BC was significantly correlated with PAHs and regional population. The BC fluxes have slightly increased since 1900s with the increasing population and cultivate area, and more significantly in 1980s. The burning of biomass and yak dung, fossil fuels, and human activities (mining, coking coal) may have important effects on the BC emission of soil in the Altay region. The change of BC and δ¹³C_BC reflected the change of local energy structure. With the regional reclamation increasing and environment- friendly industry developing, the BC source of JDY peatland is mainly the result of the interaction between biomass combustion and fossil fuel combustion.

How to cite: Luo, N., Bao, K., Yu, R., Liu, X., Tuoliuhan, Y., and Wen, B.: Centennial records of PAHs and black carbon in Altay mountain peatlands, Xinjiang, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1515, https://doi.org/10.5194/egusphere-egu21-1515, 2021.

The Athabasca Bituminous Sands (ABS) industry has dramatic benefits for the economy of Alberta, Canada. However, with increasing industrial operations, environmental concerns have grown regarding the contamination of air and water with trace elements (TEs). The ABS are composed of both minerals (ca. 85%) and bitumen (ca. 15%). While V, Ni, Mo, and Re are found primarily in bitumen, other potentially toxic TEs such as As, Cd, and Pb occur mostly in minerals. The mechanical processing of ABS by industry generates considerable volumes of dust particles from processes and sources such as open-pit mining, quarrying, road construction, petroleum coke transport and storage, and dry tailings. These dusts are dominated by coarse aerosols with short atmospheric residence times, consisting primarily of recalcitrant and sparingly reactive silicate minerals enriched in lithophile elements such as Al, Fe, and Mn. In contrast, high-temperature industrial processes such as the smelting and refining of metallic ores and coal combustion yield fine aerosols (< 2 µm) that can be transported for thousands of kilometers. These fine aerosols are respirable and mostly in the forms of oxides and hydroxides rich in TEs such as As, Cd, and Pb, posing a risk to all living organisms. Hence, it is important to differentiate between TEs in the two aerosol fractions.

Here, Sphagnum mosses collected from ombrotrophic (rain-fed) bogs within the ABS region are used as biomonitors of atmospheric deposition, and compared with mosses from a reference site 264 km to the southwest. The aim is to estimate the percentage of TEs in the fine versus coarse aerosol fractions by determining the abundance of TEs in the acid soluble ash (ASA) and acid insoluble ash (AIA) in Sphagnum. Trace element concentrations (total, in ASA and in AIA) were obtained using ICP-MS.

Concentrations of AIA and total concentrations of TEs increased towards industry, reflecting increasing dust deposition. Comparing the site nearest industry (JPH4) to the control site (UTK), the greatest differences in total concentrations were measured for lithophile elements such as Li, Be, and the lanthanides; V, Ni, and Mo were all 10x more abundant; the differences in chalcophile elements were much less apparent: Pb and Tl 6x, Ag 3x and Cu, Cd, and Zn < 2x. In AIA, Cs, Li, La, and Al were all more abundant at JPH4; Tl was slightly more abundant (3x); Ag, Cu, and Pb were all more abundant at UTK. In ASA, Th, Al, and the lanthanides were more abundant at JPH4; however, concentrations of Cd, Cu, Ag, Zn, Sb, and Tl were higher at UTK. In general, therefore, lithophile elements were more abundant in samples collected near industry, in total concentration as well as in the AIA and ASA fractions. However, chalcophile elements exhibited either insignificant differences, or were more abundant at the control site. Clearly, measuring only the total concentrations of TEs in moss from a dusty industrial region provides limited information about their associated health risks.

How to cite: Chen, N., Shotyk, W., Barraza, F., Belland, R., Javed, M. B., Cuss, C. W., and Grant-Weaver, I.: Distinguishing trace elements in acid soluble ash (ASA) and acid insoluble ash (AIA) of Sphagnum mosses within the Athabasca Bituminous Sands Region, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3795, https://doi.org/10.5194/egusphere-egu21-3795, 2021.

Palsa peatlands are a significant carbon pool in Northern hemisphere which is subjected to change due to accelerated permafrost thaw and peat decomposition with progressing global warming. On the other hand, peat deposits of palsas serve as an important conduit of information about variability of environment conditions in the past millennia and respective vegetation changes. In our study we applied the multi-proxy record to distinguish variation in hydrothermal regimes of palsa peatland in Northern Siberia and to trace the likely diagenetic alteration of accumulated peat.

The study site is located 10 km North-East of Igarka settlement (67^o31’ N, 86^o38’E) within the area underlain discontinuous permafrost. The peat core was obtained in the central intact part of elevated (ca. > 3.5 m above surrounding hollows) dry hummock. The active layer, thawed seasonally layer, at the coring site was about 0.6 m. The entire depth of peat deposit was 8.6 m, but interrupted with several relatively thin (0.1-0.2 m) ice-rich lenses. Thawed and frozen peat samples of 0.5-5.0 cm thickness (mean = 2.8 cm) were collected at 2.5-12.0 cm step (mean =5.4 cm) depending on the amount of peat material. Collected samples (n = 160) after drying at 60^oC for 48 h were subjected to the analysis for C and N content, stable isotopic composition of C and N. These measurements will further accompany radiocarbon dating, loss on ignition, plant macrofossil and macro charcoal analyses.

The analyzed 8.6 m deep peat core demonstrated the large variation of C (17.3-54.7%) and N (0.37-3.26 %) contents as well as C:N ratios (14-134). The isotopic depth profile was in the range from -24.51 to -34.31 ‰ for d¹³C and from -1.77 to 6.96 ‰ for d¹⁵N. The highest enrichment in ¹⁵N (2.69±1.60 ‰ d¹⁵N) was found in seasonally thawed layer (≤0.6 m). A layer close to the bottom (6.9-8.3 m) contained peat the most depleted by ¹³C (<-30 ‰ d¹³C). Meanwhile, along the peat profile depth we detected significant fluctuations in these parameters suggesting the different periods with specific environmental conditions.

Further combined with radiocarbon dating and plant macrofossil analyses we will attempt to capture the changes occurred during the past epochs in an input matter (vegetation changes and/or its productivity), decomposition rates as well as hydrothermal regimes and permafrost processes like aggradation (e.g. hummock uplift and cryoturbation) and degradation (e.g. hummock collapse, shifts from minerotrophic to ombrotrohic conditions and vice versa).

This work was supported by the Russian Science Foundation, project № 20-17-00043.

How to cite: Anatoly, P., Elena, N., Dmitry, K., and Sergey, S.: Peat isotopic composition of a deep deposit of palsa mire for the reconstruction of environmental changes in permafrost domain of Northern Siberia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5395, https://doi.org/10.5194/egusphere-egu21-5395, 2021.

Montane bogs—peat-forming ecosystems located in high elevation and receiving their water supply mostly from meteoric waters—are unique archives of past environmental changes. Studying these ecosystems and their responses to recent climate warming will help improve our understanding of the sensitivity of high-elevation peatlands to regional climate dynamics. Here, we report a post-bomb radiocarbon-dated, high-resolution, and multi-proxy record in Laobaishan bog (LBS), a mountaintop bog from the Changbai Mountains Range in Northeast China. We analyzed plant macrofossils and testate amoebae of a 41-cm peat core dated between 1970 and 2009 to document the ecohydrological response of peatland to the anthropogenic warming in recent decades. We quantitatively reconstruct the surface wetness changes of LBS bog using the first axis of the detrended correspondence analysis (DCA) of plant macrofossil assemblages and depth to water table (DWT) inferred by transfer function of testate amoebae assemblages. We distinguished two hydroclimate stages: the moist stage before the 1990s and the rapidly drying stage since the 1990s. During the moist stage, plant macrofossils were characterized by the low abundance of Sphagnum capitifolium and Polytrichum strichum that prefer dry habitats, and testate amoebae assemblages were dominated by low abundance of dry-adapted Assulina muscorum and Corythion dubium. High score of first axis and low DWT also suggested a moist habitat at LBS. After the transition into the drying stage, the abundance of S. capitifolium and P. strichum increased and that of A. muscorum and C. dubium showed similar trend. Score of first axis and DWT reconstructions show that LBS have experienced rapid surface desiccation since the 1990s. Based on the high-resolution gridded reanalysis data, these ecohydrological changes occurred with a rapid increase in temperature (~1°C) but without notable change in total precipitation during the growing season (May–September) since the 1990s. Besides, backward trajectory analysis showed no apparent changes in atmospheric circulation pattern since the 1990s, supporting our interpretation that the ecohydrological changes in LBS bog were induced by climate warming. These results demonstrate that the plant communities, microbial assemblages, and peatland hydrology of montane peatland show a sensitive response to climate warming that might be in larger amplitude than the low-elevation areas.

How to cite: Yang, T., Zhao, H., Xia, Z., Yu, Z., Li, H., Bu, Z., and Wang, S.: Rapid Ecohydrological Response of a Mountaintop Peatland to Recent Climate Warming in Northeast China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15329, https://doi.org/10.5194/egusphere-egu21-15329, 2021.

Sphagnum mosses have been used in some of the earliest works in biomonitoring of atmospheric deposition of trace elements (TEs). Since their adoption into the field the Sphagnaceae have become one of the foremost biomonitors. When taken as contemporary samples, these mosses have allowed us to identify spatial variations as well as trends and major changes in atmospheric deposition due to changing policy, technology, industry, and land use. While long term monitoring programs, such as the European Moss Survey, allow us to track these changes through time, these ongoing studies only reach as far back as their start dates. In the case of the European Moss Survey this was 1990. The use of materials already collected and archived in herbaria provides a low-cost method for retrospective analysis of atmospheric deposition of TEs. The critical advantage of herbarium specimens over other historical monitoring method is their high temporal resolution, as their exact collection date is known. Once collected, stored, and protected from atmospheric dust, the concentrations of non-volatile TEs present remain effectively unchanged. The oldest herbarium records can predate industrialisation, but most have records from the beginning of industrialisation, with the frequency of collection increasing in the modern era. Using only the top 2 cm of herbarium specimens of Sphagnum mosses (S. fuscum, S. angustifolium, S. capillifolium, S. magellanicum) found in Canadian ombrotrophic bogs, we will be creating historical reconstructions of atmospheric deposition in northern Alberta since the 1940s and southern Ontario since 1860’s. The first objective is to determine how best to balance preservation of the limited herbarium material available while also using sufficient material to achieve suitable levels of analytical accuracy. As TE analyses using ICP-MS are destructive and some specimens have immeasurable value from a natural history perspective, as little material as possible should be taken for analysis. Grinding of the sample was avoided, to minimize sample loss and the risk of contamination. We compared the measured concentrations obtained with ICP-MS as a function of the mass of Sphagnum digested, using selected herbarium samples as well as two certified, Standard Reference Materials (NIST 1515 and HB36-M2). These analyses allow us to determine the optimal amount of material necessary to balance the analytical accuracy and preservation of material of 4 species of Sphagnum mosses from Alberta over the last 80 years. The results will be compared with the data already available for TE concentrations in age-dated peat cores from the same region.

How to cite: Frost, L., Belland, R., Grant-Weaver, I., and Shotyk, W.: Balancing preservation of material and the need for analytical accuracy: Mass requirements of Sphagnum moss from herbarium collections for trace element analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13836, https://doi.org/10.5194/egusphere-egu21-13836, 2021.

Although interest in peatland environments, especially in terms of their carbon storage, has gained momentum in response to a heightened awareness of the climate emergency; significant gaps remain in the geographical coverage of our knowledge of mires, including some major wetland systems. This paucity has implications, not only for our understanding of their development and functioning, but also for adequately predicting future changes and thus providing effective mire environmental management. Our INTERACT-supported study provides radiometrically dated, well-characterised millennial scale peat records from two contrasting undisturbed and impacted (ditched) ombrotrophic sites in the Great Vasyugan Mire (GVM) near Tomsk, Siberia and two additional mesotrophic sites to the east of the Ob river. In addition, the geochemical record was complemented by multiproxy palaeoecological characterisation (pollen, charcoal, stable isotopes, testate amoeba). We identified both natural (lithogenic) and anthropogenic geochemical signals recording human impacts with site specific variations. Elevated trace element concentrations in the peat profiles align with the region’s wider agricultural and economic development following the colonisation of Siberia by Russia (from ca. 1600 AD) when pollen assemblages indicate the decline of forest cover and an increase in human disturbance, including the use for fire. Trace element concentrations peak with the subsequent, post WWII industrialisation of regional centres in southern Siberia (after 1950 AD). On a global scale, our sites, together with evidence from the few other comparable studies in the region, suggest that the region’s peatlands are relatively uncontaminated by human activities with a mean lead (Pb) level of < 5 mg/kg. However, via lithogenic elements including Rb, Ti and Zr, we detected both a geochemical signal as a result of historical land cover changes enhancing mineral dust deposition following disturbance, as well as fossil fuel derived pollutants as relatively elevated, subsurface As and Pb concentrations of ca. 10 and 25 mg/kg respectively with the development of industry in the region. Nevertheless, the potential significance of local factors on the sites’ geochemical profile is also highlighted. For example, we identify the effects of past peat drainage for afforestation (ca. 1960s) and the scheme’s subsequent abandonment. Although the region’s mire systems are remote and vast, they appear to hold a legacy of human activity that can be detected as a geochemical signal supporting the inferences of other palaeoenvironmental proxies. Such geochemical peat core records, from Eurasia in particular, remain relatively scarce in the international scientific literature and therefore, as yet, inadequately characterised and quantified compared to other regions.

How to cite: Hutchinson, S., Diaconu, A., Kirpotin, S., and Feurdean, A.: Geochemical peat records from the Great Vasyugan Mire and Tomsk region, Siberia. Regional temporal trend of human impact over the last 500 years and local perturbations., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11669, https://doi.org/10.5194/egusphere-egu21-11669, 2021.

Northeast China—located near the northern limit of the influence by the East Asian summer monsoon—receives most moisture through the westerly airflow, but variations in moisture contributions from the Yellow Sea in the western Pacific Ocean determine its hydroclimate during summer monsoon season. The proportion of moisture from the Yellow Sea is strongly modulated by the location and intensity of the Western Pacific Subtropical High (WPSH). However, it is still unclear how sensitive regional hydroclimate to WPSH-modulated change in moisture sources and its impact on peatland carbon accumulation. Here, we used macrofossil data and paired δ¹³C and δ¹⁸O isotope analysis of Sphagnum moss cellulose from a well-dated bog from a steep mountain slope in the Greater Khingan Mountains (~47˚N) to reconstruct peatland moisture changes and elucidate past shifts in moisture sources. δ¹³C values reflect peatland surface moisture, as dry conditions with less water film effects would increase isotopic discrimination against ¹³C and result in lower δ¹³C values. Our results from a 250-year peat record show a decrease of ~3‰ in δ¹³C from -25 to -28‰—with corresponding increase in dry-adapted moss Polytrichum—suggesting a drying trend since about 1980 AD. Also, the down-core δ¹⁸O and δ¹³C data show a positive correlation (r = 0.65, p < 0.001), in contrast with evaporative enrichment of δ¹⁸O being the dominant effect. We argue that δ¹⁸O values reflect the input of moisture derived from the Yellow Sea—that has higher δ¹⁸O values than that from the westerlies—as modulated by the WPSH. When the WPSH extends westward, it blocks moisture transport from the Yellow Sea to North China, causing low δ¹⁸O values in summer precipitation, dry conditions, and negative shifts in δ¹³C, and vice versa. Furthermore, carbon accumulation rates show a major decrease after the 1980s—despite that more recent peat tends to have higher apparent accumulation rates—suggesting a sensitive response of this steep-slope mountain peatland to shift in regional hydroclimate in monsoon-margin region of Northeast China.

How to cite: Wang, Z. and Yu, Z.: Atmospheric circulation, hydroclimate change, and peat accumulation over the last 250 years inferred from a Sphagnum peatland in the southern Greater Khingan Mountains of Northeast China , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10942, https://doi.org/10.5194/egusphere-egu21-10942, 2021.

Peat records of trace metals pollution history over thousands of years are not widely reported in northeastern Asia, although the mining/metallurgy have already started in the past 5000 years. Peat core was collected in September 2015, from the Nur Sphagnum bog, in Selenge province, in the NW part of the Kenthii Mountains, Mongolia. The Nur Sphagnum bog (49°39’N; 107°48’E; 1250 m.a.s.l.) is the largest wetland located in the mountain taiga forest of Mongolia in the northern part of the Hentei highlands. The mean January and July temperatures are -27.1°C and 18.3°C respectively, while mean annual precipitations are 288 mm. The peatland is composed of than 10 species of Sphagnum, while herb layer is dominated by Carex rostrata, and several species of Sphagnum. The dominant tree species are composed of Betulaplatyphylla, Pinussylvestris, Piceaobovata and Abiessibirica. As for the Nur bog, no research on elemental or isotopic geochemistry was undertaken currently. Our preliminary geochemical study established a baseline for typical heavy metal, Pb, 1.1 mg kg-1, which is reasonable to represent a pre-industrial background value in Mongolia, even in northeastern Asia. The average Pb content through the cores was 2.2 mg kg-1, which was significantly lower than the level in northeastern China and showed that the it was still typical area of pristine ecosystem in northern Mongolia. However, the elevation of Pb and Tl contents in the near surface layers was also observed, with an enrichment factor of 6, which suggested that the anthropogenic impact was approaching in this region and more attention should be paid to safeguard its nature heritage.

How to cite: Bao, K., Qiang, M., Zhao, K., Yan, Y., Ganzorig, U., and Batkhishig, O.: Mongolian peatland documents 5000-year pollution history and a baseline of Pb and Tl in northeastern Asia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9018, https://doi.org/10.5194/egusphere-egu21-9018, 2021.

A detailed pedocryostratigraphic scheme of the Late Pleistocene periglacial region of the East European Plain has been developed on the basis of study of the paleorelief, sediments, paleosols, and cryogenic horizons. OSL and ¹⁴C-dating of paleosols and sediments in Aleksandrov quarry and in other sections made it possible to substantiate this scheme and correlate it with analogous ones for different regions of Europe. The loess-paleosol sequence in Aleksandrov quarry (51º05'N, 36º08'E) does not have an analogous with respect to the completeness in the whole East European Plain. In the filling of paleobalka the Ryshkovo paleosol of the Mikulino interglacial (MIS 5e) is observed. Over this paleosol, the Valdai soil-sediment series (MIS 5d – MIS 2) is located. It includes four interstadial soils, two of them of the Early Valdai (Kukuevo and Streletsk ones), and two, sometimes three, of the Middle Valdai (Aleksandrov, Hydrouzel и Bryansk ones). The OSL date, 127 ± 8 ka BP, (beginning of MIS 5e) was obtained for a sample taken from the bottom of the Ryshkovo soil. The interglacial soil is overlain by the Seym layer formed mainly from destroyed and redeposited horizons of this soil. For the upper part of the Seym layer, OSL dates of 115 ± 7 ka BP and 112 ± 20 ka BP were obtained (MIS 5d). But the process of burial of Ryshkovo soil in the bottom of the paleobalka began at the end of the interglacial after a catastrophic forest fire. Large post-permafrost deformations - pseudomorphosis is confined to Selikhovodvor loess - MIS 4 (65 ± 8 ka BP). Two soils occurring between Seym and Selikhovodvor loesses: Kukuevo and Streletsk - Early Valdai (MIS 5c and MIS 5a). For Mlodat loess which separates those two soils (MIS 5b), OSL dates of 91 ± 1 and 89 ± 7 ka BP were obtained. For paleosols of Middle Valdai (MIS 3), ¹⁴C-dates were obtained: Aleksandrov (53.742 - 2.124 ka cal BP) and Bryansk soils (37.618 ± 0.668 ka cal BP). For Tuskar loess, which separates Alexandrov and Bryansk soils, OSL dates of 50 ± 3 and 51 ± 3 ka BP were obtained. The new stratigraphic scheme of Late Pleistocene agrees with the ideas of researchers from Eastern, Central, and Western Europe , which allows the following correlations. The identified paleosols correspond to the following intervals: Ryshkovo – Eemian interglacial (127-117 ka BP); Kukuevo to Amersfoort + Brørup – Saint-Germain 1 (105-95 ka BP); Streletsk – Odderade to Saint-Germain 2 (about 85-75 ka BP); Aleksandrov to Oerel (56-53 ka BP); Hydrouzel to Moershoofd – Poperinge (44-45 ka BP) and Hengelo (40-38 ka BP); and Bryansk (33-27 ka BP) to Stillfried B, Denekamp or Grand Bois interstadials. The reconstructed Late Pleistocene loess-paleosol sequence has the most similar structure with loess-paleosol sequences of Ukraine, with sequence Dolní Věstonice in Moravia (Czech Republik), Stillfried in Austria and Mainz-Weisenau in the Rhenish area (Germany), and other archives. This work was supported by RFBR, grant N19-29-05024 mk.

How to cite: Sycheva, S., Frechen, M., Terhorst, B., Sedov, S., and Khokhlova, O.: Stratigraphy and chronology of Late Pleistocene loess-paleosol sequence of the East European Plain and correlation with Late Pleistocene archives of Europe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-650, https://doi.org/10.5194/egusphere-egu21-650, 2021.

Loess-palaeosol sequences are the most intensively studied terrestrial archives used for the reconstruction of late Pleistocene environmental and climatic changes in the Sea of Azov region, southwest Russia. Here we present a revised luminescence-based chronostratigraphy and a multi-proxy record of late Pleistocene environmental dynamics of the most complete and representative loess-palaeosol sequences (Beglitsa and Chumbur-Kosa sections) from the Azov Sea region. We propose a new chronostratigraphy following the Chinese and Danubean loess stratigraphy models that refines the subdivision of the last interglacial palaeosol (S1) in two Azov Sea sites, resolves the uncertainty of the stratigraphic position of the weakly developed paleosol (L1SSm) in Beglitsa section, and allows direct correlation of the Azov Sea sections with those in the Danube Basin and the Chinese Loess Plateau. More importantly, it adds important data to better constrain local and regional chronostratigraphic correlations, and facilitates the interpretation of climatic connections and possible forcing mechanisms responsible for the climatic trend among these regions. In addition, a general succession of environmental dynamics is reconstructed from these two vital sections, which is broadly consistent with other loess records in the Dnieper Lowland and Lower Danube Basin, demonstrating similar climatic trends in these regions at glacial-interglacial time scales. However, differences in details were also identified, especially for palaeosols developed during the last interglacial period, and the cause of these dissimilarities between loess records appears complex.

Furthermore, our results have important implications for the chronostratigraphic representativeness of Beglitsa as a key loess section and the reconstruction of the temporal and spatial evolution of late Pleistocene palaeoclimate in the Sea of Azov region.

How to cite: Chen, J.: Revised chronostratigraphy and palaeoenvironmental record of loess-palaeosol sequences in the Azov Sea region of Russia since the late Pleistocene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3207, https://doi.org/10.5194/egusphere-egu21-3207, 2021.

Here we investigate the timing of Pleistocene-Holocene climatic transition as reflected in nine luminescence dated loess-palaeosol sequences across the northern hemisphere, from the Chinese Loess Plateau, the southeastern European loess belt and the central Great Plains, Nebraska, USA.
First, logs of high-resolution magnetic susceptibility and its frequency dependence were used as palaeoclimatic proxies to define the environmental transition from the last glacial loess to the current interglacial soil. Second, the onset of increase in their values above typical loess values was used to assess the onset of, and developments during, the Pleistocene-Holocene climatic transition. The variability seen in the magnetic susceptibility records are interpreted based on high-resolution luminescence dating applied on multiple grain-sizes (4-11 µm, 63-90 µm, 90-125 µm) of quartz extracts from the same sample. In order to increase the overall precision of the luminescence based chronology we rely on weighted average ages. Based on these, Bayesian modeling allowed the determination of age-depth models and mean sedimentation rates for each investigated site.
The magnetic susceptibility signal shows a smooth and gradual increase for the majority of the sites from the typical low loess values to the interglacial ones. At all but one site, this increase, associated to the onset of the Pleistocene-Holocene boundary (ie., 11.7 ka) was dated to 14 ka or even earlier. Our results highlight the need of combining palaeoclimatic proxies (magnetic susceptibility) with absolute dating when placing the Pleistocene-Holocene climatic transition as reflected by the evolution of this proxy in order to avoid misinterpretations in loess-paleosol records caused by simple pattern correlation. These results indicate diverse environmental dynamics recorded in the different North Hemisphere loess regions during the major global climatic shift from the last glacial to the Holocene.
The detailed luminescence chronology coupled with magnetic susceptibility records indicate the formation of accretional Holocene soils in the sites investigated. Modeled accumulation rates for the Holocene soil are similar for European, Chinese and American loess sites investigated and vary from 0.02 m/ka to 0.09 m/ka.

How to cite: Constantin, D., Mason, J., Hambach, U., Veres, D., Panaiotu, C., Zeeden, C., Zhou, L., Marković, S., Gerasimenko, N., Avram, A., Tecsa, V., Sacaciu-Groza, S. M., del Valle Villalonga, L., Begy, R., and Timar-Gabor, A.: Accretional soil formation in northern hemisphere loess regions - evidence from OSL-dating of the P/H climatic transition from China, Europe and North America, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2394, https://doi.org/10.5194/egusphere-egu21-2394, 2021.

In this work, the samples of red-coloured pedosediments were analyzed. They were found in two sections of the Lori Basin, Armenia - Kurtan-IV and Yagdan. Micromorphological analysis, the measurement of magnetic susceptibility, particle size distribution, CHN, determination of bulk, and biomorphic composition was made. Based on the results of previous studies, the age of the deposits overlying these sections was known. The pedosediment from the Kurtan-IV section is overlain by a mixture of sand and volcanic ash, which is dated at about 1.4 Ma (Calabrian). The pedosediment from the Yagdan section is overlain by 2-2.5 Ma basaltic lava (Gelasian). As a result of our research, it was revealed that both pedosediments were formed in conditions differ from current ones and have differences between themselves also. The pedosediment from the Yagdan section was formed during the dominance of the subtropical climate. It was revealed the presence of manganese-ferruginous and clayey films, a low index of carbonization and salinity, and a relatively high index of weathering. Pedo-sediments from the Yagdan section can be classified as Cambisols with vitric, argic, chromic qualifiers. By the time the later section Kurtan-IV was formed, the climate became cooler, which was reconstructed by the appearance of phytoliths of coniferous plants. Pedosediment from the Kurtan-IV section can be classified as Stagnic Luvisols. The later factors influencing the preservation of pedosediments and changes in their composition and properties were identified. Thus, the upper horizon of the Yagdan section sharply differs from the underlying ones in increased weathering and oxidation, and these properties are retained up to the third layer. It has increased indicators of magnetic susceptibility and the content of copper elements, cobalt, nickel, vanadium, chromium, which were brought in by basalt lava. The pedosediment from the Kurtan-IV section was overlain by lacustrine deposits, which led to a decrease in the magnetic susceptibility and an increase in the SiO₂ content and carbonation index. This work was supported by RFBR, grant N19-29-05024 mk.

How to cite: Revunova, A. and Khokhlova, O.: Red-coloured pedosediments of the Lori Basin, Armenia , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14619, https://doi.org/10.5194/egusphere-egu21-14619, 2021.

In the framework of climate change research, alpine soils may provide excellent paleoenvironmental information, thus representing a powerful tool for paleoclimate reconstruction. However, since Pleistocene glaciations and erosion-related processes erased most of the pre-existing landforms and soils, reconstructing soil and landscape development in high-mountain areas can be a difficult task.

This study was performed in the periglacial environment of the Stolenberg Plateau (LTER site Istituto Mosso), located on the watershed between Valsesia and Lys Valley, at the foot of the southern slope of the Monte Rosa Massif (Western Italian Alps, elevation: ca. 3030 m a.s.l.). The plateau is covered by thick periglacial blockfields and blockstreams, with a plant cover that reaches no more than 3-5% of the surface.

These periglacial landforms unexpectedly revealed well-developed soils below the superficial coarse deposits. In particular, below the stone layer, thick (between 30 and 65 cm) umbric horizons were observed, under which discontinuous cambic Bw ones were developed. In contrast, the surrounding snowbed communities (Salicetum herbaceae) were characterized by Regosols or Cambisols with 10-15 cm thick A horizons and weak signs of cryoturbation.

Despite the sparce plant cover, the organic carbon (C) stocks were surprisingly high (above 5 kg*m^-2), comparable to vegetated and even forest soils at lower elevation. In addition, geophysical investigations showed that these soils are widespread under the stony cover, with a thickness ranging between 20 and 90 cm.

Radiocarbon dating (¹⁴C) indicated that these soils are paleosols, probably originated during the main warming phases/interstadials occurred between the end of Last Glacial Maximum and the beginning of the Neoglacial. In particular, the ages of the oldest samples were 20.5-20 ka cal. BP (values obtained from two independent and blind datings performed in different moments), others were dated ca. 17.5, 13, 8.5, 6.5, 5.7 ka cal. BP, while the youngest ages were 4.4-4.1 ka cal. BP.

These dates, particularly the oldest ones, show that the Stolenberg Plateau was presumably free of ice at the beginning of the Early Lateglacial, and its summer temperatures were already compatible with some kind of vegetation development. The origin of these unexpected high-elevation soils, below blockstreams and blockfields, is of great relevance for unraveling the climatic history in the Western Alps. The results, including the soil characteristics, the geomorphological framework and the specific local landform setting, aspect, and position, suggest that the plateau may have been a Nunatak, which acted as a refugium for alpine vegetation during the last glacial pulses, serving as a hot-spot for the rapid reoccupation of deglaciated high-elevation landscapes.

How to cite: Pintaldi, E., D'Amico, M. E., Colombo, N., Giardino, M., and Freppaz, M.: Hidden paleosols at high elevation in the Alps (Stolenberg Plateau - NW Italy): evidence for a Lateglacial Nunatak?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5354, https://doi.org/10.5194/egusphere-egu21-5354, 2021.

Hyperarid (< 80 mm yr^-1) soils in hot deserts are characterized by accumulations of soluble salts (gypsum and halite) in diagnostic horizons as a result of limited moisture availability. In most desert terrains, the source for pedogenic gypsum and halite is atmospheric dust and rainwater. The interplay between climatic properties such as frequency and intensity of rain events, rainfall composition, dust flux, and evaporation rates, govern the depth and concentration of these salts. Better understanding of these relationships can improve our estimation of regional paleoenvironmental and paleoclimate conditions. Up to date, only empirical correlations between annual rainfall and pedogenic salt horizons are available.

The goals of this study are to: 1) quantify rates of pedogenic gypsum accumulation with time and the role of controlling climatic conditions that govern its accumulation, 2) estimate the most likely climatic scenarios that led to the formation of the diagnostic gypsic horizon developed in late Pleistocene (~ 60 ka) abandoned alluvial fan surfaces in the hyperarid Negev desert,  southern Israel. To achieve these goals, we constructed a compartment model that simulates gypsum accumulation in soil and tests its sensitivity to various changes in the long-term climate properties. The model predicts gypsum content and depth of accumulation in the soil profile over thousands of years and more. The input parameters are stochastically simulated rainstorms, evaporation, dust flux, and sulfate concentration in rainwater, at daily time steps. The model was tested and calibrated using data of Holocene (< 11 ka) soil profiles developed on stable alluvial fans in the hyperarid Negev. With the assumption that the climate during the Holocene was not much different than today (i.e., mean annual rainfall < 50 mm). Sensitivity analyses indicate that gypsum accumulation is highly sensitive to mean annual rainfall and sulfate concentration in rainwater. Synthetic gypsum profiles were calculated using different climate scenarios and compared to late Pleistocene soils. Our results suggest that: (a) gypsum accumulation in late Pleistocene soils cannot occur simply by extending current climate conditions for a much longer duration. (b) The plausible climate scenarios for the late Pleistocene must include additional rain input (1.5 – 2.0 times than mean annual rainfall today) and increased sulfate concentration in rainwater (2.0 – 2.5 times than today) to successfully reconstruct the observed accumulated gypsum in mature (60 – 12 Ka) soil profiles.

How to cite: Siman-Tov, L., Crouvi, O., Morin, E., Amit, R., Enzel, Y., Marra, F., J. Reznik, I., and Rosenzweig, R.: Evaluating climate effects over long-term salts accumulation in hyperarid soils using stochastic modeling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2296, https://doi.org/10.5194/egusphere-egu21-2296, 2021.

Soil carbon isotopes (δ¹³C) provide reliable insights at the long-term scale for the study of soil carbon turnover and topsoil δ¹³C could well reflect organic matter input from the current vegetation. Qinghai-Tibet Plateau (QTP) is called “the third pole of the earth” because of its high elevation, and it is one of the most sensitive and critical regions to global climate change worldwide. Previous studies focused on variability of soil δ¹³C at in-site scale. However, a knowledge gap still exists in the spatial pattern of topsoil δ¹³C in QTP. In this study, we first established a database of topsoil δ¹³C with 396 observations from published literature and applied a Random Forest (RF) algorithm (a machine learning approach) to predict the spatial pattern of topsoil δ¹³C using environmental variables. Results showed that topsoil δ¹³C significantly varied across different ecosystem types (p < 0.05).  Topsoil δ¹³C was -26.3 ± 1.60 ‰ for forest, 24.3 ± 2.00 ‰ for shrubland, -23.9 ± 1.84 ‰ for grassland, -18.9 ± 2.37 ‰ for desert, respectively. RF could well predict the spatial variability of topsoil δ¹³C with a model efficiency (pseudo R²) of 0.65 and root mean square error of 1.42. The gridded product of topsoil δ¹³C and topsoil β (indicating the decomposition rate of soil organic carbon, calculated by δ¹³C divided by logarithmically converted SOC) with a spatial resolution of 1000 m were developed. Strong spatial variability of topsoil δ¹³C was observed, which increased gradually from the southeast to the northwest in QTP. Furthermore, a large variation was found in β, ranging from -7.87 to -81.8, with a decreasing trend from southeast to northwest, indicating that carbon turnover rate was faster in northwest QTP compared to that of southeast. This study was the first attempt to develop a fine resolution product of topsoil δ¹³C for QTP using a machine learning approach, which could provide an independent benchmark for biogeochemical models to study soil carbon turnover and terrestrial carbon-climate feedbacks under ongoing climate change.

How to cite: Lai, Y., Li, S., Tang, X., Luo, X., Liu, L., Shi, Y., and Yu, P.: Spatial variability of topsoil δ13C across Qinghai-Tibet Plateau, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5768, https://doi.org/10.5194/egusphere-egu21-5768, 2021.

Geomorphometric information can be exploited to study the most extensive and common landforms that humans have ever produced: agricultural terraces. An understanding of these historical ecosystems can only be determined through in-depth knowledge of their origin, evolution, and current state in the landscape. These factors can ultimately assist in the future preservation of such landforms in a world increasingly affected by anthropogenic activities. High-resolution topographic (HRT) techniques allow the mapping and characterization of geomorphological features with wide-ranging perspectives at multiple scales. From HRT surveys, it is possible to produce high-resolution Digital Terrain Models (DTMs) to extract important geomorphometric parameters such as topographic curvature, to identify terrace edges, even if abandoned or covered by uncontrolled vegetation. By using riser bases as well as terrace edges (riser tops) and through the computation of minimum curvature, it is possible to obtain environmentally useful information on these agricultural systems such as terrace soil thickness and volumes. The quantification of terrace volumes can provide new benchmarks for soil erosion models, new perspectives for land and stakeholders for terrace management in terms of natural hazard and offer a measure of the effect of these agricultural systems on soil organic carbon (SOC) sequestration. This work aims to realize and test an innovative and rapid methodological workflow to estimate the minimum anthropogenic reworked and moved soil of terrace systems in different landscapes. This aspect of new technology and its application to terrace soil-systems has not been fully explored in the literature. We start with remote terrace mapping at a large scale (using Airborne Laser Scanning) and then utilize more detailed HRT surveys (i.e., Structure from Motion and Terrestrial Laser Scanning) to extract geomorphological features, from which the original theoretical slope-surface of terrace systems were derived. These last elements were compared with in-field sedimentological recording obtained from the excavations across the study sites to assess the nature of sub-surface topographies. The results of this work have produced accurate DTMs of Difference (DoD) for three terrace sites in central Europe in Italy and Belgium. The utilization of ground-truthing through field excavation and sampling has confirmed the reliability of the methodology used across a range of sites with very specific terrace morphologies, and in each case has confirmed the nature of the reconstructed, theoretical original slope. Differences between actual and theoretical terraces from DTM and excavation evidence have been used to estimate the minimum soil volumes and masses used to remould slopes. Moreover, geomorphometric analysis through indices such as sediment connectivity permitted also to quantify the volume of sediment transported downstream, with the associated and mobilized C, after a collapsed terrace. The quantification of terrace soil volumes provides extremely useful standards for further multi-disciplinary analysis on the terrace sediments themselves, aiding physical geographers, geoarchaeologists, palaeo-environmentalists, and landscape historians in the understanding of terrace systems and the impact of agricultural processes on the landscape.

How to cite: Cucchiaro, S., Paliaga, G., Fallu, D. J., Pears, B. R., Walsh, K., Zhao, P., Van Oost, K., Snape, L., Lang, A., Brown, A. G., and Tarolli, P.: A geomorphometric approach to estimate soil volumes stored in agricultural terrace systems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1772, https://doi.org/10.5194/egusphere-egu21-1772, 2021.

The activities of ancient population strongly affected the development of landscapes and soils in Western Siberia during the late Holocene. It should be noted that studies devoted to the processes of natural and anthropogenic evolution within this vast territory are extremely irregular. Thus, the significant proportion of the materials on the dynamic of Siberian landscapes in the Holocene, related to the studies of various natural archives and archeological monuments, falls on the southern part of region. On the one hand, this situation is due to the relatively recent development of Western Siberia in relation to the development of hydrocarbon deposits, on the other hand, on the peculiarities of the relief and landscapes prevailing in the central and northern parts of the West Siberian Plain. A significant part of the territory under consideration is characterized by low, poorly dissected relief, which largely contributes to its bogging and widespread distribution of organogenic peat soils. It is not surprising that the deposits of lakes and peat bogs are the main natural archives that provide information on the dynamics of the natural environment within the central parts of Western Siberia and, first of all, the taiga zone, while the potential of mineral soils and sediments from this point of view is insignificant, compared to other regions. At the same time the boreal zone of Western Siberia is very large and includes regions with more complex geomorphological conditions.

To assess the possibility of using buried soils and colluvial layers in the middle taiga of Western Siberia for reconstruction of the Holocene landscape’s dynamics, we carried out research on two key sites with rather contrast relief and high frequency of archeological sites: in the middle Yugan River Basin and in the North of the Kondinskaya Lowland. Buried soils and colluvial sediments in a number of sections characterizing foots of the steep slopes on the border with peat bogs were selected as objects for our study. Based on the obtained radiocarbon dates it is possible to preliminarily identify several stages of the activation of erosional processes. For the north of the Kondinskaya lowland three remarkable phases of erosional activity were identified, while for the Yugan River Basin the number of phases was larger - 6. It is interesting to note that the obtained results make it possible to correlate these two regions. The presence of a larger number of recorded erosion-pyrogenic events for the Yugan River basin reflects a longer permanent human presence in the area under consideration, which is also consistent with archaeological data.

The study was funded by the Ministry of Science and Higher Education of the Russian Federation and was performed as a part of project FEWZ-2020-0007 “Fundamentals of the natural environment history of the south of Western Siberia and Turgay in the Cenozoic: sequence sedimentology, abiotic geological events and the evolution of the Paleobiosphere“. The studies were carried out using the equipment of the Center for Collective Use "Bioinert Systems of the Cryosphere", Tyumen Scientific Center, SB RAS and RFBR, project number 20-04-00836.

How to cite: Kurasova, A., Konstantinov, A., Loiko, S., and Kulizhskiy, S.: Evaluating the potential of buried soils and colluvial layers for tracking natural and human-induced transformation of landscapes in the middle taiga of Western Siberia , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16454, https://doi.org/10.5194/egusphere-egu21-16454, 2021.

Changes in land use represent, after fossil-fuel combustion, the greatest cause of greenhouse-gases emission into the atmosphere. Coastal wetlands, also referred as coastal blue carbon ecosystems (e.g. salt marshes, mangrove forests, seagrass meadows, swamps), represent one of the most powerful C sinks among the Earth’s ecosystems, being capable to sequester organic carbon (OC) at rates ca. 30-50 times higher than terrestrial forests. Historically, land reclamation for agriculture, farming and urban expansion, severely impacted coastal wetlands, causing their loss and degradation. Wetlands drainage lead to the oxidation of organic matter previously stored under anaerobic conditions and the release of CO₂ into the atmosphere. Only recently the critical role of blue carbon ecosystems in climate-change mitigation has been recognised, highlighting the importance of protecting and studying these precious environments.

In this work, changes in land use in the last two centuries are reconstructed through comparison with historical maps. At the beginning of the 19^th century Napoleon Bonaparte requested the development of high-quality maps of occupied territories. Among these, the so-called ‘Carta del Ferrarese’ (CdF), completed between 1812 and 1814, is composed of 38 sheets and represents, to a scale of 1:15.000, 240.000 hectares of the Po lowlands, roughly corresponding to the present-day Ferrara district. The CdF, archived at the Kriegsarchiv in Vienna, is an extraordinary example among historical maps for its high quality and accuracy, which constitute a two-centuries-old reliable paleo-landscape picture.

Within the Historical Land Use Change research project, leaded by the Emilia-Romagna Statistical and GIS Service, the CdF was scanned, accurately georeferenced and orthorectified, showing a surprising generalized match with recent maps. More than 31.000 polygons were digitized in a GIS environment and interpreted on the basis of the European Corine Land Cover codes, properly modified for the land uses at the time.

Comparison with the recent land use analysis, carried out in 2014, highlights changes in land use, mainly related to land reclamation. Salt marshes and swamps, originally extended for 100.000 hectares, were reduced of about 85%, starting from 1861. Major phases of land reclamation occurred in 1870s and 1960s. Geochemical analyses on shallow samples (depth < 50 cm), depict OC content of artificially drained soils < 5% of the total volume. Soil texture testifies to the almost complete mineralization of OC after reclamation. Only recently drained soils show higher OC content, in the range of 10-15%.

How to cite: Meli, M. and Bruno, L.: Changes in land use in the last two centuries in the Po lowlands (northern Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9780, https://doi.org/10.5194/egusphere-egu21-9780, 2021.

In 2018, the Voorthuizen-Wikselaarseweg archaeological site was excavated. This settlement dates back to Roman and Medieval times and is located in the central part of the Netherlands: the so-called Gelderse Vallei, an area build-up of fluvioperiglacial and eolian sands. Questions related to the anthropogenic influence of settlers on the surrounding landscape, as well as the specification of the ancient agricultural activity, were among the main research tasks posed to this archaeological study. Despite the fact that modern geoarchaeology offers a variety of methods of researching archaeological sites, in practice, the vast majority of archaeological work in the Netherlands is limited to the use of palynological and macrobotanical analyzes and radiocarbon dating. The choice of research methods in relation to the sandy cultural layer is especially narrow as it is assumed to bear worse conditions of preservation of traces of anthropogenic activity.

For the investigation of the sandy cultural layer of Voorthuizen, a method of microbiomorphic (phytolith) analysis was proposed. The information that is given by this method is different from that provided by palynological study (though they strongly complement each other). While pollen provides a general insight into the plant growth in the region around the settlement, phytoliths (silica copies of plant cells)  present data on the plant species grown, eaten, and used on the settlement itself. This information is contained in the old living layer, as well as in the pits (working places and waste pits), postholes, ditches etc. The combination of phytoliths and other microbiomorphs (e.g. detritus, diatoms, etc.) essentially broadens the range of palaeoecological information.

In Voorthuizen 34 samples have been collected and processed according to standard sample treatment technique (Golyeva, 2008). All samples were found to be suitable for analysis, with a sufficient number of microbiomorphs.

The results of the study not only allow to clarify significantly the archaeological interpretation of the site but also provides new information on the anthropogenic impact on the landscape. Microbiomorphic analysis manifests the genesis of the cultural layer and the several phases and types of anthropogenic use of the territory. The research also demonstrates the applicability of the microbiomorhic (phytolith) analysis in the case of sandy archaeological layers.

References:

Golyeva А. А., Microbiomorphic complexes of natural and anthropogenic landscapes. Genesis, geography, informative capacity (LKI, Moscow, 2008) (in Russian).

How to cite: Druzhinina, O., van den Berghe, K., and Golyeva, A.: Application of the microbiomorphic (phytolith) analysis in the geoarchaeological study of the land-use at the Voorthuizen-Wikselaarseweg archaeological site (Netherlands) , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9043, https://doi.org/10.5194/egusphere-egu21-9043, 2021.