The middle reaches of the Yellow River (MYR) cover a significant portion of the Loess Plateau, rendering it among the most heavily impacted regions by soil erosion globally. Consequently, the MYR are characterized by high-intensity soil and water conservation measures, such as terracing and silt check dams, which exert a profound impact on soil erosion and sediment transport in this region. However, there is currently no accurate and clear assessment of sediment interception and sediment reduction contributions for large-scale and complex cascading silt check dams. This study enhances the Revised Universal Soil Loss Equation (RUSLE) model by coupling the processes of soil erosion, slope sediment production, and channel sediment transport. The study evaluates the slope erosion and sediment production through the combination of RUSLE and the Sediment Connectivity Index (IC). Additionally, it calculates the sediment interception and sediment output in the channel based on silt check dams sediment interception efficiency. Accurate classification of complex cascading silt check dams is crucial for assessing their sediment reduction contributions. The research employs a flow-based method for precise dam classification and incorporates the latest terracing distribution data to accurately assess the sediment reduction contributions of high-intensity engineering measures in the MYR. The research findings indicate: (1) The average annual soil erosion rate in the MYR from 1981 to 2017 is 13.32±31.94 t ha^-1 yr^-1, with moderate to severe soil erosion covering 15.1% of the area. (2) Over the past 40 years, there has been an overall decreasing trend in soil erosion in the MYR, with a significant reduction covering 8.65% of the area. Significant decreases in soil erosion began to appear after 2000, with an average annual soil erosion rate reduction of 0.34 t ha^-1 yr^-1. (3) Based on the cascading situation of silt check dams, the 2187 large silt check dams in the MYR are classified into 6 categories. Taking the initial siltation year as an example, for basins controlled by silt check dams, the sediment output rate without silt check dams is 3.444 t ha^-1 yr^-1, while with silt check dams, the sediment output rate is 0.468 t ha^-1 yr^-1, achieving a sediment reduction contribution of 86.4%. The upcoming tasks include: (1) investigating the interannual fluctuations in sediment reduction attributed to silt dams and validating the model; (2) formulating diverse scenario assumptions to evaluate the sediment reduction contributions from engineering measures and vegetation restoration. This study seeks to precisely evaluate the impact of high-intensity soil and water conservation measures on mitigating soil erosion and sediment transport in the MYR, offering insights for regional soil and water conservation practices and sustainable management.

How to cite: Huang, Y., Gao, G., and Wang, Y.: Effect of high intensity soil and water conservation engineering measures on soil erosion and sediment transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4527, https://doi.org/10.5194/egusphere-egu24-4527, 2024.

Rill erosion is one of the most significant water erosion types in the agricultural areas as a complex type of concentrated flow erosion process. And, it is known that hydraulic conditions are closely related to rill development in terms of the initial soil moisture contents. However, the impact of the subsoil hydrology on sediment discharge potentials is somewhat entangled. Thus, many recent studies point out that the change in soil erosion depends on hydrological conditions in the subsoil and suggest that the evaluation of those changes would increase the success of soil erosion estimates to more efficiently manage natural resources. This study was aimed to investigate the effects of different soil moisture settings (referred as dry, saturated and drainage) on rill erodibility (Kr) and critical shear stress (τcr) values of the soils as the significant variables of process-based WEPP model, and the relations between basic soil properties (e.g. particle size distribution, aggregate stability, soil mechanical cohesion, organic matter etc.) and these model variables for the heavy textured 12 soil types (clay contents change between 33 and 52 %). Flume experiments were performed by using a V-shaped mini-flume apparatus, which was 0.046 m wide, 0.5 m long, and 0.12m deep, specifically designed for rill experiments. Two V-shaped channels with a length of 0.2 m were cemented to the flumes, one on each side. The soil samples were packed in boxes to attain natural bulk densities of the soils after passing through a 2 mm screen opening. The slope steepness was set to 3% for the slope bed and the flow rate was controlled with a flow meter from 0.10 L min^-1 to 0.65 L min^-1. Within the scope of the study, the mechanical soil cohesion values of the soils were determined by the fluidized bed approach. Obtained results clearly showed that the initial moisture contents had significant effects on sediment concentrations. The lowest Kr values were observed for the drainage condition in all soils while the highest Kr value was obtained for the soils with higher clay than silt content in the saturated conditions. Under dry conditions, on the contrary, the latter reversed and there was the highest Kr value for the soils having higher silt contents than clay. The inverse relationship between Kr and τcr was very pronounced and the highest τcr value was measured under drainage conditions. In addition, it was observed that there were significant correlations between rill erodibility (Kr) and silt contents and mechanical soil cohesion variables of the soils. Conclusively, rill erodibility potential of the soils observed under concentrated flow conditions had statistically close relationships with initial moisture conditions and primary physical soil properties (p<0.01). The research findings experimentally confirmed that variations in subsoil hydrology would play a crucial role in new generation studies of process-based modelling of the rill erosion.

Key words: Rill erodibility, critical shear stress, WEPP, initial soil moisture content

Acknowledgements: This work was supported by the Scientific and Technological Research Council of Turkey [TUBİTAK-3001, Project no: 118O111].

How to cite: deviren saygin, S., Ari, F., Temiz, C., Arslan, S., Unal, M. A., and Erpul, G.: Effects of the Initial Soil Moisture Contents on Rill Erodibility and Critical Shear Stress of the Clay-rich Soils  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-190, https://doi.org/10.5194/egusphere-egu24-190, 2024.

As a result of intensive agricultural practices, cultivated soils of the European loess belt can experience high levels of degradation by erosive runoff. Given the sometimes severe and costly on- and off-site impacts, the agricultural community is urged to adopt alternative cropping techniques to mitigate runoff and erosion. Several cropping practices related to conservation agriculture are known for their ability to mitigate surface flows, but the magnitude of their effectiveness is associated with a wide variability due to environmental or management factors. The influence of these factors on the practices’ effectiveness is still poorly understood in quantitative terms. We therefore quantitatively reviewed the effectiveness of three common conservation farming practices at controlling runoff and soil loss. A systematic search was performed, focused on the plot scale and the Western European context, and meta-analyses were carried out on the 35 collated relevant studies involving 239 individual trials (plot-years). Two different approaches suitable for hierarchically structured datasets were used for the meta-analyses: hierarchical nonparametric bootstrapping and linear random effects models. Both methods yielded very similar outcomes, but the lack of primary data sometimes restricted the ability to account for all hierarchical levels of the dataset in the random effects models. We found that, on average, winter cover crops decrease cumulative seasonal (autumn-winter) runoff by 68% and soil erosion by 72% compared to a bare soil. The level of stubble tillage on the control plot, the number of successive years of cover cropping, and the maximum vegetation cover reached are three key variables explaining the mitigation effect of winter cover crops. In potato crops, tied-ridging (=(micro)basin tillage) cut cumulative seasonal (spring-summer) overland flow by a mean of 70% and soil loss by 92% compared to conventional furrows, but no moderators could be identified to explain the variability across studies or trials. Conservation (non-inversion) tillage techniques alleviate cumulative seasonal runoff by 27% and associated sediments losses by 66% on average, but a publication bias is strongly suspected for this meta-dataset. These mitigation effects are much greater for spring crops than for winter crops, and increase over time since ploughing stopped. The type of conservation tillage schemes also affects the capacity to attenuate surface flows. Intensive non-inversion tillage schemes based on multiple (powered) tillage operations turns out to be the least effective at reducing both water and soil losses. The best performing scheme against runoff appears to be a deep non-inversion tillage (-61%), while against erosion it would be a direct drilling system (-82%). Coarser-textured soils (sandy loam) also respond slightly better to conservation tillage than (clay-)loams. Although several factors could partly explain the effectiveness of two of the three conservation practices considered in this study, there remains a high (unexplained) variability between trial effect sizes, thus not attributable to sampling variability. Meanwhile, this review provides farm advisors or policy makers with guidance on the conditions in which such conservation practices are expected to achieve the greatest benefits.

How to cite: Clement, T., Bielders, C., and Degré, A.: Effectiveness of conservation tillage, tied-ridging, and winter cover crops at controlling runoff and soil loss in the Western European context: a meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2129, https://doi.org/10.5194/egusphere-egu24-2129, 2024.

Past nuclear weapons testing and nuclear power plant accidents resulted in the ubiquitous deposition of radionuclides in the environment. While the risks associated with radionuclide contamination are apparent, these fallout radionuclides (FRNs) provide the privileged markers (“golden spikes”) of the Anthropocene stratigraphic layers. The onset of their emissions in the 1950s coincided with the “Great Acceleration”, which is characterized by large-scale shifts in the biophysical and socio-economic aspects of the Earth System, including an increase in soil degradation, triggered mainly by land-use change. Among the host of FRNs deposited globally, ¹³⁷Cs has been the most commonly used and ^239+240Pu is a new emerging tracer and chronological marker to assess soil erosion and/or chronology of sediment deposition.

In this meta-analysis, we compiled existing ¹³⁷Cs and ^239+240Pu data analyzed from undisturbed soils in the literature to get an overview of the spatial distribution and constraints of fallout ¹³⁷Cs and ^239+240Pu in Equatorial and Southern Hemisphere soils, as well as the possible sources of these FRNs through their isotopic ratios. A database composed of 1087 reference cores was built from the literature published on Equatorial and Southern hemisphere soils.

Aside from the cores collected from the north equatorial regions, high ¹³⁷Cs inventories were also found in reference soils collected at the 40-50° S latitudinal band, which were mostly from South America. On the other hand, high ^239+240Pu inventories were found at the 20-30° S latitudinal band, but this was influenced by the unusually high inventories measured from the French Polynesia, where many nuclear weapons testing occurred. The ^240/239Pu atomic ratios indicated that sources other than the global fallout (^240/239Pu = 0.18) contributed to the reference inventories in the Southern Hemisphere. As some areas lacked measurements, specific points where additional data could be obtained were identified through a GIS-based approach to represent the entire land surface areas of interest adequately. Together with new measurements, the compiled reference soil data will be used to construct a detailed baseline map of ¹³⁷Cs and ^239+240Pu fallout mainly for regional soil erosion assessments.

How to cite: Dicen, G., Guillevic, F., Chaboche, P.-A., Meusburger, K., Sabatier, P., Evrard, O., and Alewell, C.: Spatial distribution of fallout 137Cs and 239+240Pu in Equatorial and Southern Hemisphere soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3077, https://doi.org/10.5194/egusphere-egu24-3077, 2024.

Erosion is recognized as a major threat worldwide and can be dramatically observed in Northwestern France as a consequence of water runoff. Recent regional studies in Normandy suggested that off-site erosion and runoff impacts led to significant economic costs over the last 25 years. Even if the regional planning strategy against erosion and runoff impacts could be seen as effective with a cost-benefice balance greater than 1, this strategy will no longer be as effective by 2050 due to climate change effects in the near future. To address this issue and conduct efficient land and water degradation neutrality strategies, local stakeholders now have to identify complementary strategies based on the deployments of nature-based solutions. However, there is a lack of references on the effectiveness of these complementary strategies.

In this study, we conducted a modelling exercise with the WaterSed model at the regional scale (12,318 km²) aiming to: (i) quantify the hydro-sedimentary transfers reaching the karstic systems throughout the 15,000 sinkholes distributed across the territory, (ii) established the first regional cartography of vulnerability of sinkholes to runoff and erosion, and (iii) to evaluate the effectiveness of strategies considering nature-based solutions to prevent land and ground water degradation.

The model was calibrated and validated using data of hydro-sedimentary transfer monitoring station on a local catchment. Multiples scenarios were explored (impacts of different nature-based solutions densities, localization of grasslands, ploughing of grass lands, soil and water conservation techniques, etc.) using semi-automatic positioning algorithm.

The WaterSed model provided specific outputs like volume of runoff (m³) and volume of sediments (t) reaching the karstic system for different designed storms. The mean runoff per sinkhole was estimated between 7,700 and 23,200 m³ and the mean volume of sediment reached between 0.8 and 4.7 t per sinkhole.

Our results suggest that increasing the density of nature-based solutions from 2 to 8 per km² can reduce from 0.5 to 1.3 % the runoff volume and from 5 to 15 % the sediment load reaching the sinkholes. Our results also suggest that a complement of 20 m to 250 m of grassland upstream a sinkhole can reduce the sediment load from 5 to 13 % and the runoff from 0.5 to 1.5 %. Our results suggest that the localization of ploughed-up grasslands can have a significant impact on the generation of hydro-sedimentary transfers (up to 10 % more sediment discharge).

The results of this modeling exercise provided: (i) the first regional cartography of vulnerability of the 15,000 sinkholes to runoff and erosion, and (ii) local thresholds and valuable references to build and conduct efficient land and ground water degradation neutrality strategies with stakeholders.

How to cite: Maurié, A., Patault, E., Ledun, J., Deman, M., and Fournier, M.: Identification of thresholds to conduct efficient soils and water conservation strategies against erosion impacts: new insights from a modelling prospective in Normandy (France), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3799, https://doi.org/10.5194/egusphere-egu24-3799, 2024.

Land degradation is a primary form of global environmental deterioration. Soil erosion and land desertification are common land degradation processes in many regions. In this research, we take the Zhuoshui River basin in central Taiwan as the study area, and investigate the environmental sensitivity of different land use/land cover to land degradation subjected to historical and future climate scenarios. In order to understand the quality of land resources in the study area, we used the evaluating framework of the Mediterranean Desertification and Land Use (MEADALUS) model with revisions according to the localized mountainous characteristics in central Taiwan, and calculated the Environmentally Sensitive Areas Index (ESAI) of the study area. The ESAI is comprised of five indicators, which include climate, soil, vegetation, management, and landslide indicators. For the climate index, observed data from 2001 to 2020 of weather factors were used in the historical scenarios. On the other hand, data of weather factors generated by MIRCO5 GCM considering RCP2.6 and RCP8.5 scenarios in near-term and long-term time scales were used for the climate indicator in the future scenarios. The results depict the spatial variation of environmental sensitivity to land degradation in the Zhuoshui River basin using numerical values ranging from 1 to 2, where higher values correspond to more severe degradation. It is evident that the upper reaches of the Zhuoshui River exhibit lower degrees of land degradation due to dense vegetation, higher elevations, and limited human presence. In contrast, the downstream areas show a higher trend of land degradation, with the wet season exhibiting lower degradation trends compared to the dry season. Furthermore, there is a slight upward trend in land degradation since 2015, primarily attributed to climate indicators, as soil and vegetation indicators, as well as anthropogenic management indicators, show no significant changes. The land degradation index shows relatively subtle differences between future scenarios and historical scenarios, with land degradation index variations ranging from -13% to 22%. Negative values in the degradation index differences indicate an improvement in the degree of degradation, while positive differences denote an exacerbation of land degradation. According to the land use distribution in the Zhuoshui River basin, the land degradation trends for forests and national parks show relatively consistent variations between the dry and wet seasons. However, in the middle and lower reaches of the basin, apart from the RCP85 scenario for the long-term period, the other three scenarios exhibit higher differences in land degradation index changes for agricultural and urban areas compared to historical values. The research provides a reference for preventing continued land degradation and conserving terrestrial ecosystems and biodiversity in the study area.

How to cite: Wang, Y.-C. and Lu, Y.-H.: Evaluating the environmental sensitivity to land degradation: a case study in central Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8, https://doi.org/10.5194/egusphere-egu24-8, 2024.

Soil erosion represents a primary threat to soil systems with adverse implications for ecosystem services, crop production, potable water, and carbon storage. While numerous studies have quantified the spatial distribution of Above-Ground Biomass (AGB), soil erosion, and Soil Organic Carbon (SOC) in the Yangtze River Basin (YRB) in China, limited attention has been given to assessing the contributions of different land use types and especially crop types to AGB, soil erosion, and SOC. In most studies, cropland is taken as a land use class, while detailed crop types and rotation patterns, and their effect on soil erosion and SOC, vary significantly. In this study, we used the Metronamica model to generate a detailed crop rotation and distribution map across the YRB and subsequently employed the PESERA model to simulate the spatial distribution of AGB, soil erosion, and SOC on a monthly basis. PESERA model simulations indicate an average soil erosion rate across the entire YRB of 7.7 t/ha/yr, with erosion hotspots concentrated in the Sichuan Basin and the central-southern regions. The southwestern region and western Sichuan show elevated levels of AGB and SOC, while the eastern plains display lower levels. Erosion rates are lowest in areas designated as artificial land, pasture and grassland, whereas cropland and fruit trees experience the highest erosion rates. In terms of crop types, the highest erosion rates and lowest AGB are observed in fallow and potato cultivation, while the lowest erosion rates and highest AGB are found in rice-wheat rotation fields. To the best of our knowledge, this is the first study including detailed crop types and patterns into account while evaluating their effect on relatively large scale (i.e. YRB). These findings can help to develop sustainable soil management and (cropping) conservation strategies.

How to cite: Zhou, J., Baartman, J., Ning, Y., Carvalho Nunes, J., Ma, L., and Liu, X.: Quantifying above-ground biomass, SOC and erosion using a new detailed crop pattern map including double and triple cropping in the Yangtze River basin using the PESERA model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4784, https://doi.org/10.5194/egusphere-egu24-4784, 2024.

Soil loss due to crop harvesting (SLCH) is a globally occurring, but underestimated process that contributes to soil degradation, adversely affecting soil functionality and fertility. In northern Europe, sugar beets play a crucial role for SLCH due to their high production rates, yet there is a lack of research in commercial mechanized farming of sugar beets. The aim of this study is to measure SLCH for sugar beets using typical commercial harvesters and identify relationships to crop and soil variables. Therefore, sugar beets and soil samples were collected for 14 sampling sites between 2018 and 2020 in Northern Germany.

The results show that SLCH is in average 0.064 kg per kg sugar beet (SLCHspec), which corresponds to a loss of 5.7 Mg ha^-1 harvest^-1 (SLCHcrop). These numbers are higher than former comparable studies and 83.9 % higher than SLCH estimates by sugar beet factories. In addition, we found that i) SLCH considerably varies among years, fields, but also within fields, ii) the most influential drivers for SLCH are soil water content and clay content, iii) soil properties impact SLCH differently in dependence to soil water content, iv) SLCH of sugar beets can lead to significant nutrient and soil organic carbon losses. Thus, the results underline that SLCH is an important and underestimated determinant of soil erosion processes, which urgently needs to be considered in models and estimates additionally to concurrent processes like water, wind and tillage erosion. This is important for the adaptation of soil conservation measures in order to reduce ongoing soil degradation, especially in highly mechanized agriculture.

How to cite: Saggau, P., Busch, F., Brunotte, J., Duttmann, R., and Kuhwald, M.: Soil loss due to sugar beet harvesting is an underestimated but significant soil erosion process in mechanized agricultural systems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19354, https://doi.org/10.5194/egusphere-egu24-19354, 2024.

The impact of land degradation on the environment is multidimensional and is fundamentally influenced by various land degradation processes, which usually interact spatially in a convergent manner. However, the spatial pattern of multiple converging (co-occurring) land degradation pathways remains largely unexplored in Europe. To address the synergistic (convergent) nature of land degradation, in this work we modelled and mapped the spatial pattern of twelve interacting processes in agricultural/arable environments of Europe. Therefore, using state-of-the-art and large-scale datasets that were modelled via appropriate GIS (Geographic Information System) techniques, we performed an unprecedented investigation on land multi-degradation in 40 European countries. Essentially, we found that up to 27%, 35% and 22% of pan-European agricultural/arable landscapes are synergistically affected by one, two and three land degradation processes, while 10–11% of continental agricultural/arable environments are cumulatively threatened by four and at least five co-occurring processes. Our multi-process framework can be a valuable scientific tool for complex modelling of land degradation, but also for applying various agricultural, climate or sustainable development policies at European level.

How to cite: Pravalie, R., Borrelli, P., Panagos, P., Niculiță, M., Bandoc, G., Patriche, C., and Roșca, B.: Towards a unifying approach of land degradation in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12401, https://doi.org/10.5194/egusphere-egu24-12401, 2024.

Adequately assessing the export of sediments and dissolved solids at the outlet of representative watersheds provides extremely interesting information on the behavior of these watersheds, with important environmental and management implications. To this end, the Government of Navarre (Spain) began to implement in 1995 a network of five watersheds representative of different agricultural and forestry conditions in Navarre. La Tejería and Latxaga watersheds, occupy about 200 ha each in a humid sub-Mediterranean climate and are almost completely cultivated with winter grain. Oskotz Principal watershed comprises 1,688 ha under sub-Atlantic climate, most of it covered with forest (61%) whereas the remaining area is covered by pastures and arable land. Within the Oskotz watershed, a 434 ha sub-watershed almost fully covered with forest namely Oskotz Forested, is also monitored. Landazuria watershed covers an area of 480 ha being its climate dry Mediterranean. Over 88% of the watershed area is cultivated, with about 60% of the total cultivated area under pressurized irrigation systems. The rest of the cultivated surface is rainfed agriculture. Average anual suspended sediment concentration are 182 mg/L for La Tejería, and 38, 12, 12, and 30 (median) for Latxaga, Oskotz Principal, Oskotz Forested and Landazuria, respectively. Average anual exported sediment are 4.3 ± 3.7, 1.4 ± 1.7, 1.2 ± 0.9, 0.7 ± 0.6 and 0.3 ± 0.5 Mg/ha for the same watersheds. The average annual export of dissolved solids for the same watersheds is 1.1, 1.1, 2.2, 1.9 and 2.2 Mg/ha.

As for 2010, the 5,500 ha Cemborain river basin (583 mm of precipitation at its outlet) has been incorporated into the monitoring, with the intention of understanding the behavior of a much larger and more complex basin. The dominant land uses are forestry and scrubland (70% of the basin), while cultivated soils cover about 25% of the surface area. The data corresponding to this basin, still very preliminary, are presented for the first time and contextualized in this work. The mean suspended sediment concentrations in Cemboráin are 120 mg/l, with a great temporal variability, increased by suspiciously high values in summer, possibly due to the presence in the samples of various residues instead of sediments. The average sediment export at the outlet of the basin is 3 kg/ha/day in the winter months (January to March), which is 5.0 and 2.8 times lower than those found in La Tejería and Latxaga watersheds (the most similar in terms of climate and soils) for the same period. The average export of dissolved solids was 2.2 kg/ha/day, a figure 3.7 and 4.6 times lower than those found in La Tejería and Latxaga watersheds, respectively. Practically all exports in Cemborain have occurred between December and March. The low sediment export figures are consistent with what is to be expected given that the soil is much more protected than in the cereal basins.

How to cite: Percaz, M., Barberena, I., Campo-Bescós, M. A., Giménez, R., and Casalí, J.: Improving our understanding of sediment and dissolved solids export in Mediterranean croplands: comparative analysis of the response of watersheds with contrasting characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16461, https://doi.org/10.5194/egusphere-egu24-16461, 2024.

Soil erosion is one of the major processes of land degradation. Climate change, marked by alterations in the precipitation spatial and temporal patterns as well as rainfall amounts projected to increase, is expected to exacerbate soil erosion and loss of soil in the agricultural landscape. Understanding soil loss using physically-based water erosion prediction models and improving knowledge of soil erosion of agricultural lands under future climate change scenarios is critical to developing best management practices for the conservation of soil resources as well as to inform decision and policy makers. This study aims at investigating the impacts of future climate changes on soil erosion in the United States. By integrating up-to-date climate datasets this study characterized differences and current trends in precipitation with respect to climate change and applied a climate model ensemble based on the CMIP6 climate scenarios to predict the future climate. These data are downscaled with machine learning algorithms. It also estimates soil erosion in different soil-climate-agricultural management systems from predicted precipitation under future climate change scenarios using the Revised Universal Soil Loss Equation, Version 2 (RUSLE2). Research findings on the impacts of future climate change scenarios on soil erosion in agricultural landscapes will allow the development of climate-driven best management practices and conservation agriculture techniques as well as inform decision and policy makers to reduce soil loss, therefore protecting the limited soil and water resources, and contributing to a sustainable agricultural production and food security.

How to cite: Ghorbani, M., El Kadiri, R., Momm, H., Yoder, D., Dalmo, V., Bingner, R., Wells, R., Ferruzzi, G., and Darnault, C.: Predicting soil erosion under climate change: Using climate data to forecast future climate change scenarios and RUSLE2 modeling to estimate soil erosion on agricultural lands in the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6779, https://doi.org/10.5194/egusphere-egu24-6779, 2024.

The Revised Universal Soil Loss Equation, Version 2 (RUSLE2) is the water erosion prediction tool for use by the USDA National Resources Conservation Service (NRCS) for all conservation planning in the United States. USDA NRCS utilizes the Integrated Erosion Tool (IET) that combines RUSLE2 with USDA data sets for soil, climate, and agricultural management. The Agricultural Research Service (ARS) is the USDA’s research agency charged with the development of the RUSLE2 model. RUSLE2 is an advanced computer model that estimates rill and interrill erosion by water, combining empirical and process-based science, for use on personal computers. This research aims at improving RUSLE2 science components, including the development of a web-based user interface for RUSLE2, for use by USDA NRCS. Advanced science components will be developed to quantify rainfall and land management effects on spatial and temporal variability of dynamic soil properties in agricultural watersheds in the United States, with emphasis on the assessment of soil erodibility and the risk of soil erosion under climate change. State-of-the-art technologies needed to measure, identify, and link dynamic soil erodibility to soil loss in the agricultural landscape, such as machine learning algorithms, remote sensing, and non-intrusive visualization and imaging technologies will provide advanced science components for RUSLE2. For the development of a web-based RUSLE2 modeling system, a new cloud based infrastructure is being deployed using the Amazon Web Services (AWS) platform, which will support online databases for climate, soil, and agricultural management data. A new database structure is being designed for RUSLE2, to support server based erosion calculations. AWS services will also provide web servers, spatial databases, geoprocessing capabilities, cooperative source code development and all compute and storage resources. These research findings and products will help understand how climate change and modern management practices impact soil erodibility dynamics. Improvements to RUSLE2 technology will lead to advances in determining soil loss across agricultural landscapes through improved physically based water erosion models. New web-based tools will provide best management practices for soil and water resources conservation under changing environments, contributing to sustainable agriculture and food security, while ensuring environmental health.

How to cite: Darnault, C., Ghorbani, M., Genc Kildirgici, G., Kethineedi, A., Ghimire, B., Calhoun, J., Momm, H., Yoder, D., Dalmo, V., Bingner, R., Wells, R., and Ferruzzi, G.: Revised Universal Soil Loss Equation, Version 2 (RUSLE2) Development: Advanced science components and web-based user interface for use in conservation planning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6852, https://doi.org/10.5194/egusphere-egu24-6852, 2024.

A healthy soil supports life on Earth through maintaining ecosystems that provide food, feed and fibre whilst supporting Earth system functions such as waste recycling, climate, flood, and water regulation. The intensification of anthropogenic activities and climate challenges pose serious threats to soil health (Hassani et al., 2021), exacerbating the processes of soil degradation that are putting at risk soil management, biodiversity, and food security.

This study thus aims at enhancing our understanding of the state and changes of soils by combining machine learning methods with a comprehensive series of climate and environmental variables. We employ machine learning methods to analyze the relationships between soil health indicators and a wide range of climatic parameters, and chemical, physical, and biological soil attributes in Europe. Capitalizing on the LUCAS (Land Use/Cover Area frame statistical Survey) topsoil database (2009-2018) and digital soil mapping techniques, our preliminary results highlight the regions across Europe showing consistent decline in soil nutrients and carbon content, signaling potential risks of soil degradation. The proposed framework enables us to understand, document and respond to soil changes in ecosystems under different land management and climate scenarios. This contributes to devising necessary action plans for sustainable soil management and preservation.

This research is part of the project AI4SoilHealth (Accelerating collection and use of soil health information using AI technology to support the Soil Deal for Europe and EU Soil Observatory) funded Horizon Europe (Grant No. 101086179).

Reference

Hassani, A., Azapagic, A., Shokri, N. (2021). Global Predictions of Primary Soil Salinization Under Changing Climate in the 21st Century, Nat. Commun., 12, 6663. https://doi.org/10.1038/s41467-021-26907-3.

How to cite: H. Afshar, M., Hassani, A., Aminzadeh, M., Borrelli, P., Panagos, P., Robinson, D. A., and Shokri, N.: AI-driven insights into soil health and soil degradation in Europe in the face of climate and anthropogenic challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9512, https://doi.org/10.5194/egusphere-egu24-9512, 2024.

Erosion is one of the most important threats for soil. Over the long term, soil erosion can have serious on-site (e.g. decrease in agricultural yield) and off-site impacts in morphogenic zones but also important off-site (e.g. mudflow) impacts in plains. Much more efforts have been devoted to study erosion processes in morphogenic zones that have naturally higher erosion rates than plains. However, the intensification of agriculture during the latter part of the 20^th century significantly altered landscapes and increased hydrosedimentary connectivity in agricultural plains. The off-site consequences are numerous: mudflows, increasement a river turbidity, siltation in rivers, transfers of pollutants associated with sediments, etc. Generally, in temperate climate, the main source of sediments is the surface runoff that occurs on fields during winter or spring but in lowland areas the subsurface drainage network is a supplementary pathway for runoff and sediments. The few studies that have quantified erosion over a complete hydrological year show subsurface drainage contribution to erosion is very variable. It is still difficult to propose a hierarchy and to quantify factors affecting soil erosion by subsurface drainage. In this study, suspended solids (SS) concentration and water flow of a lowland field have been measured during two consecutive years both at the outlets of surface and subsurface drainage networks. SS yield was 0.49 t ha^-1 and 1.08 t ha^-1 in 2019–2020 and 2020–2021, respectively. During 2019–2020 and 2020–2021, subsurface drainage contribution to the total runoff was 46% and 21%, respectively and its contribution to SS yield was 9% and 11%, respectively. High temporal resolution measurements of SS concentrations showed the suspended sediment concentration increased at the outlet of both surface and subsurface drains from the first to the second year. These variations and the increase of surface runoff rate suggest a shift in water and sediment connectivity at the field scale. Based on water tracing, water balance and analysis of rainfall characteristics, the main driver is likely cropping practices. This study confirms the majority of sediment exports occurs during a short period, cause by only few runoff event of winter and adds a new quantification of hydrosedimentary fluxes in a surface and subsurface drained field separating surface and subsurface drainage contribution. It also shows that in hydromorphic drained areas, despite the very slight slope, surface runoff can represent the major pathway for soil erosion. Adapted soil tillage practices must be developed to preserve the agricultural production capacity of the fields, maintaining water exports, while simultaneously reducing sediment exports.

How to cite: Gaillot, A., Cerdan, O., Salvador-Blanes, S., Vanhooydonck, P., Grangeon, T., Desmet, M., and Delbart, C.: Hydrosedimentary functioning of a lowland field with both surface and subsurface drainage., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10802, https://doi.org/10.5194/egusphere-egu24-10802, 2024.

Soil erosion is a significant process in the loss of soil/land resources, degradation and desertification. Traditionally, wind and water erosions have been studied and modelled separately. A quantitative sediment flux measure from a specific soil due to both water and wind erosion is lacking. The study aimed to drive such erosion rates in a semi-arid loess soil that is subjected to both forces of erosion. Soil samples from top-and sub-layers of the soil were analyzed for physical and chemical properties, including characteristics of soil aggregation. We performed targeted laboratory experiments using a boundary layer wind-tunnel for wind erosion and rainfall simulator for water erosion. Rates of sediment flux that were calculated for the topsoil and the subsoil revealed an opposite trend between water and wind erosion. This indicates that soil erodibility strongly depends on the erosional force applied rather than a certain soil property. The study conducted in a semi-arid region and may serve as a case study under climate change scenarios, in which more (non-arid) regions will be subjected to increase soil erosion.    

How to cite: Katra, I., Ben-Hur, M., and Tanner, S.: Comparison of soil erosion rates by wind and water in a semi-arid loess soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12285, https://doi.org/10.5194/egusphere-egu24-12285, 2024.

To appropriately place soil conservation measures, locating the most vulnerable areas prone to soil erosion is required. Available tools to locate vulnerable areas are tedious to use and time-consuming, and most water erosion estimations are based on empirical models with limited applicability. The present study takes advantage of two large-scale soil and water conservation tools available for the Midwest U.S.: the Daily Erosion Project (DEP) and the Agricultural Conservation Planning Framework (ACPF).

In this study, we will showcase a recently developed large scale modeling approach implemented in the Midwest U.S. that currently downscales DEP from Hydrologic Unit Code (HUC) 12 (~90 km²) average estimation of hillslope runoff and soil loss into a much finer resolution, a field and pixel scale. The DEP uses the Water Erosion Prediction Project (WEPP) and simulates hundreds of thousands of hillslopes across the Midwest, covering the wide range of factors including topography, climate, soils and land use and management.

This presentation will introduce the newly developed quantitative soil erosion assessment tool (named OFEtool - Overland Flow Element tool) that uses geographic information systems (GIS) and a physical-based model with real climate data (DEP). The OFEtool analyzes a watershed and groups areas with similar attributes, such as slope, soil type, land use, and management practices (information provided by the ACPF). Following watershed analysis, the tool uses DEP simulations to obtain average hillslope soil erosion or deposition rates for these grouped characteristics. Finally, it associates and assigns these rates to the respective areas within the watershed.

The current version of the tool is used by the ACPF to locate the most vulnerable fields across the watershed for conservation planning scenarios to prioritize interventions in fields and specific areas with the highest erosion rates. The applicability of the tool will be shown for the state of Iowa (approximately 145,746 square kilometers). Preliminary results corroborate spatial variability of soil erosion within watersheds and Major Land Resource Areas (MLRA). The presentation will also provide new insights into the main factors governing soil erosion in Iowa (climate, soils, topography, land use and management).

References

Gelder, B., Sklenar, T., James, D., Herzmann, D., Cruse, R., Gesch, K., & Laflen, J. (2018). The Daily Erosion Project – daily estimates of water runoff, soil detachment, and erosion. Earth Surface Processes and Landforms, 43(5), 1105–1117. https://doi.org/10.1002/esp.4286

Daily Erosion Project. (n.d.). Retrieved January 9, 2024, from https://www.dailyerosion.org/

Tomer, M. D., Porter, S. A., James, D. E., Boomer, K. M. B., Kostel, J. A., & McLellan, E. (2013). Combining precision conservation technologies into a flexible framework to facilitate agricultural watershed planning. Journal of Soil and Water Conservation, 68(5). https://doi.org/10.2489/jswc.68.5.113

Agricultural Conservation Planning Framework. (n.d.). Retrieved January 9, 2024, from https://acpf4watersheds.org/

How to cite: Luquin, E., Gelder, B., Herzmann, D., Zimmerman, E., James, D., Karnish, K., and Cruse, R.: A GIS-modeling strategy to locate vulnerable agricultural fields and prioritize conservation efforts across the Midwest United states., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13949, https://doi.org/10.5194/egusphere-egu24-13949, 2024.

Deforestation for cropland expansion in the sloping landscapes along the East African Rift system causes severe soil erosion and thus the loss of fertile, organic rich topsoil. However, the varying effect of land degradation in the region on soils developed from different parent material - which may influence soil fertility and carbon stabilization - are still largely unknown. To examine these factors, we compared soil organic carbon (SOC) and soil fertility indicators in undisturbed forest topsoils with cropland hillslope topsoils along a chronosequence after deforestation (2–7, 10–20, 20–40, > 60 years of cropping, land abandonment) on mafic (South Kivu, Democratic Republic of Congo) and felsic parent material (western Uganda). From previous studies, we expected higher soil fertility and SOC contents and therefore slower degradation on mafic soils due to the higher amounts of clay and pedogenic metal phases which stabilize SOM and thus further maintain soil fertility.
However, we found similar SOC contents on both parent materials and a consistent decrease with time after deforestation. SOC values were significantly lower in soils that were cleared more than 60 years ago, compared to cropland which was cleared 2–7 years ago and nearby undisturbed forest topsoils (0–10 cm soil depth). While the effective cation exchange capacity (ECEC) positively correlated with SOC in soils on felsic parent material, this was not observed in soils with mafic parent material, where it correlated with mineralogical proxies (total reserves in bases). In both regions, SOC did not correlate with clay content. Mid-Holocene carbonate volcanism appears to have offset soil degradation in the felsic region, contributing to higher pH and ECEC and impeding land abandonment due to the maintenance of acceptable soil fertility levels. Surprisingly, abandoned cropland sites in the mafic region still had an average SOC content of 14–29 g kg^-1 in topsoils, likely due to strong fixation of SOC with reactive metal phases; however, they were characterized by extremely low pH values and high Al³⁺ mobility, combined with low available nutrient status.
Our results emphasize that soil fertility and carbon stabilization are reliant on the mineral composition of the underlying parent material, even in deeply weathered soils of the humid tropics. Soil organic matter in degraded tropical cropland soils does not appear to be a reliable indicator of soil fertility.

How to cite: Summerauer, L., Bamba, F., Akoraebirungi, B., Wobusobozi, A., Drake, T. W., Kabaseke, C., Muhindo, D., Cizungu Ntaboba, L., Ramirez-Lopez, L., Six, J., Wasner, D., and Doetterl, S.: Parent material modulated effects of soil degradation on fertility and organic carbon of tropical cropland soils in Eastern Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15313, https://doi.org/10.5194/egusphere-egu24-15313, 2024.

Soil erosion causes severe on- and off-site effects, such as reductions in soil depth, eutrophication of water bodies, loss of organic matter, and clogging and smothering of riverine habitats. Attempts to assess water-induced soil erosion by water include modelling, measuring/monitoring, the use of tracers, and dating. All of these approaches have shown to have shortcomings (Parsons, 2019). The main objective of this research is to assess soil erosion in a small agricultural catchment (HOAL, Lower Austria) using modelling, OSL-dating, 137Cs and field measurements and to compare the gained results in the light of the shortcomings of each method. The study has been conducted in a small catchment (ca. 66 ha), located in the Northern foothills of the Eastern Alps in Austria (i.e. an area intensively agriculturally used since the Middle Ages). The catchment elevation ranges from 268 to 323 m a.s.l. and has a mean slope angle of 8 %. The lithology mainly consists of Tertiary marly to sandy deposits which are superimposed by Quaternary sediments (e.g. loess). The climate in this region is characterized as humid. The results of this study reveal significant – partly even dramatic - differences in soil erosion rates as derived from the different assessment methods. Details as well as a critical method comparison will be provided at the EGU General Assembly 2024.

References:
Parsons, A. J. (2019). How reliable are our methods for estimating soil erosion by water? Science of the Total Environment, 676, 215-221.

How to cite: Pöppl, R., Renschler, C., Abatti, B., Asimus, N., Kraushaar, S., Strauss, P., and Fuchs, M.: Assessing soil erosion in a small agricultural catchment in Austria using OSL-dating, modelling, 137Cs and field measurements: a critical comparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9422, https://doi.org/10.5194/egusphere-egu24-9422, 2024.

The Government of Navarre (Spain) began to implement in 1995 a network of five watersheds representative of different agricultural and forestry conditions in Navarre. In this paper we focus on 4 of them. La Tejería and Latxaga watersheds occupy about 200 ha in a humid sub-Mediterranean climate and are almost completely cultivated with winter grain. Oskotz Principal watershed comprises 1,688 ha under sub-Atlantic climate, most of it covered with forest (61%) whereas the remaining area is covered by pastures and arable land. Within the Oskotz watershed, a 434 ha sub-watershed almost fully covered with forest namely Oskotz Forested, is also monitored.

Ten-minute data on flow (Q), water turbidity (T) and the most important meteorological variables are recorded in all the watersheds. Samples are collected daily to determine the concentration of suspended sediments (SSC) and various dissolved substances.  In addition, and since 2006, during particularly heavy rainfall-runoff events, another parallel sampling is activated to determine the sedimentogram in much greater detail. The number of samples taken depends on the Q and T variations detected.

For this study, events have been selected that meet the following requirements: i) there is a clear raising flow phase and a clear decreasing flow phase; ii) at least six samples have been collected and processed throughout the event for SSC determination; iii) the linear regression between Q and T yields a value of r2> 0.75. From this regression equation it is possible to obtain a very detailed sedimentogram (tenminute basis).

A total of 30 events meet the requirements, 7 in La Tejería, 9 in Latxaga, 5 in Oskotz Forestal and 9 in Oskotz Principal.  Hysteresis is observed in all of them. In the cereal watersheds, 75% of the hysteresis curves are of hourly character, that is, with the peak of the sedimentogram located in the rising part of the hydrograph. In these watersheds, the remaining 25% correspond to curves with a complex structure linked to the occurrence of several flow peaks in the same event, which will require further study. In the Oskotz Forestal watershed 3 of the curves are clockwise and two are "eight" shaped, while in Oskotz Forestal 8 of the nine curves are clockwise and one is "eight" shaped.

These preliminary results suggest that in the cereal watersheds the main sediment sources are in the proximity to the watershed outlet, probably in the same channels. In the Oskotz watersheds, the main sources are also mostly located in the vicinity of the outlet, although occasionally other sources far from the outlet are also activated, mainly in the forest watershed.

How to cite: Casali, J., Otazu, M., Barberena, I., Campo-Bescós, M. A., and Giménez, R.: Analysis of high-resolution flow vs. suspended sediment concentration curves to determine sediment sources in agricultural and forestry watersheds with contrasting characteristics , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18835, https://doi.org/10.5194/egusphere-egu24-18835, 2024.

Soil erosion, in its various forms, has been identified as one of the major soil threats worldwide because it is one of the most significant forms of land degradation (soil truncation, loss of fertility, slope instability, etc.) and loss of soil- based ecosystem services; causing irreversible effects on the poorly renewable soil resource. The Revised Universal Soil Loss Equation (RUSLE) is one of the most widespread adopted empirical model approaches for assessing long-term average soil loss rate by water erosion. The assessed soil loss rate is an indicator that describes (or measures) the state of the soil erosion in a specific area (field, catchment, region, country) which we are interested in. The quality of this indicator relies on the scale which it represents and its required data. Many European countries, such as Italy, do not have harmonised national soil erosion databases at the different scales required by decision makers (regional, provincial, local) and national scale assessments have been carried out using EU data (JRC 2015, LUCAS 2018). However, national scale assessments are not often coherent with the more detailed information available at regional scale for some Italian regions in which RUSLE based potential soil erosion maps have been produced. Although it would be predictable, it is of particular interest to assess how reliable a national scale assessment can be in providing information on the state of soil erosion at a regional scale. A regional soil database is available for the Tuscany region (IT) and it is suitable for soil erosion assessment at regional scale. In this context, within the framework of the EJP SOIL project SERENA, the study was aimed at comparing three RUSLE applications carried out i) at regional scale by means of the available regional soil/climate/digital terrain model data; ii) at national scale by means of the same datasets upscaled at country level; iii) at national scale based on datasets actually available for all the Italian territory.

This scale effect is likely due to 2 components. First, the spatial density and quality of the observations needed to estimate the RUSLE factors. To this regard, soil and climate data quality and availability are usually higher for small territories than for the whole national territory. Secondly, the reference scale adopted for the aggregation and spatialization of the data, which is particularly important for the LS factor. These two reasons lead to a lower reliability of the RUSLE applications at national scale as compared to a regional one. The assessment at the regional scale of the soil loss rate using the Tuscany Region dataset was used as reference to evaluate the results obtained with the other two datasets at the same regional scale. Such comparisons were made using both the differences among the erosion maps, and through statistical indices that measure the deviations between the reference map and the other spatial products.

How to cite: Medina-Roldán, E., Buttafuoco, G., Gardin, L., Lorenzetti, R., and Ungaro, F.: Comparison of national and regional assessments of soil loss rate by water erosion: an application to the Tuscany region (Italy)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17115, https://doi.org/10.5194/egusphere-egu24-17115, 2024.