PICO
This session aims to address this research gap and will focus on recent studies aiming to better understand the process of rill and gully erosion, with the ultimate aim of developing predictive tools and effective management strategies. As such we welcome contributions on: monitoring and measurement techniques; the factors and processes controlling rill, piping and gully erosion; modelling approaches; restoration and control; and the role of piping, rills and gullies in hydrological and sediment connectivity.
During soil erosion, sediment load of rill flow changes dynamically and may affect its hydraulic characteristics. However, current research on hydraulics of sediment-laden rill flow primarily uses river sand/artificial homogeneous materials as sediment, which significantly differ from natural soil, leaving a research gap on how soil quantity impacts rill flow hydraulics. This study uses natural soil in an indoor rill flume simulation experiment to explore how sediment load influences hydraulic characteristics of rill flow, including flow velocity (V), Darcy–Weisbach friction coefficient (f), Reynolds number (Re), Froude number (Fr), and flow depth (h). Experiments were conducted under combinations of six different sediment loads, five flow discharges, and five slopes. The results indicated that V, f, Re, Fr were significantly influenced by sediment concentration. V and Fr show an upward trend as the sediment load increases, while f, Re, and h demonstrate a downward trend. The sediment load predominantly influences V, f, and Fr, accounting for contributions of 0.33, 0.49, and 0.39, respectively. The influence of slope gradient on V and Fr intensifies as the sediment load increases, while the impact of flow
discharge on V, f, and Fr diminishes. As flow discharge increases, the effect of sediment load diminishes on V and Fr, and that of slope gradient strengthens. Two kinds of prediction equations were developed for estimating thehydraulic parameters of sediment-laden rill flow. The models demonstrate high R2 values (0.74 to 0.98), suggesting strong performance of the prediction equations. These findings lay a foundation for the better development of a physical process-based rill erosion model. Given the differences in the properties of natural soils,which may impact hydraulic characteristics, it is a limitation of this study that it only focuses on a single soil type, and thus future research should explore the effect of sediment properties on hydraulic characteristics.
How to cite: Shen, N.: Variability of hydraulic characteristics of sediment-laden rill flow under various slopes, water flows and sediment loads , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3668, https://doi.org/10.5194/egusphere-egu26-3668, 2026.
The mountainous relief of Georgia, along with the complex geological and geomorphological conditions within river basins – especially in their upper reaches – promotes the development of erosion processes. Depending on their form of manifestation, erosion processes may in some cases be visually imperceptible. This is particularly true with surface, or sheet, erosion, which is often less noticeable.
Studies confirm that the climate change in the alpine part of the mountainous regions of Georgia is characterized by warming, leading to intensified weathering, intensive glacier melting, increased rainfall intensity, and enhanced snowmelt, which in turn increases the amount of solid material. This is further compounded by intensified soil erosion and the intense development of agriculture in the middle and lower reaches of the river valleys. It is evident that glacier retreat and the melting of permanent ice cover will increase the transportation of solid sediment material from slopes into river valleys.
At the same time, it is possible that the increased amount of solid sediment, due to river regulation, may not be transported downstream, and a significant portion may be temporarily deposited within the river system, in alluvial valleys and floodplains, also partially altering the longitudinal profiles of rivers.
The amount of solid sediment material in Georgia's rivers shows an increasing trend. Reliable assessment and forecasting of these processes in the future represent one of the most important tasks.
How to cite: Sulashvili, T., Trapaidze, V., Kalandadze, I., Bregvadze, G., and Kalandadze, B.: Changes in River Solid Discharge in the Context of Climate Change: The Case of Georgia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4230, https://doi.org/10.5194/egusphere-egu26-4230, 2026.
Significant progress has been made in gully erosion research since the early 2000s. However, quantifying the 3-dimensional evolution of gullies at regional and global scales remains a major challenge in soil erosion science.
The first challenge is the multidimensional gap. While global assessments have successfully mapped gully head distributions (0D) and the characterization of linear gully densities (1D) has been achieved in specific countries and regions, accurate gully sediment budgeting requires a shift towards three-dimensional (3D) volumetric quantification of gully structure . The primary technical requirement is the large-scale inversion of gully depth, which can be addressed through the integration of modern geodetic techniques—including high-precision field surveys, Unmanned Aerial Vehicle (UAV) photogrammetry, and satellite stereoscopic mapping—with AI-driven predictive algorithms. Parallel to this is the temporal gap. Most regional datasets remain static. Resolving these spatial and temporal challenges is the prerequisite for transitioning from purely morphological descriptions to robust, process-based gully erosion models at large scales. The convergence of multi-source remote sensing now offers opportunities to reconstruct gully development (in 3-D) over recent decades. Coupled with the advancement of AI, which facilitates a transition from labor-intensive manual digitizing to automated, high-throughput workflows, it is now feasible to achieve rapid, dynamic, and intelligent extraction of gully information.
This report systematically examines these methodological challenges and evaluates potential solutions through the integration of multi-modal remote sensing, field measurements, and advanced analytical frameworks. To demonstrate these solutions, we present case studies from the Chinese Loess Plateau and the Northeast Black Soil Region based on small-watershed units, including 1,300 remote-sensing survey units and 65 high-precision units integrating field measurements with UAV surveys. These data provide the foundation for validating AI-driven depth inversion and automated extraction methodologies at a regional scale. Finally, we propose an international cooperation initiative to harmonize data collection and standardize validation protocols. Such a collaborative framework is essential to effectively integrate gully erosion into the next generation of global soil loss and Earth system models.
How to cite: Wang, C., Liu, B., Cruse, R., Vanmaercke, M., Chen, Y., Ma, L., Pang, G., and Yang, Q.: Bridging the Dimensional and Temporal Gaps in Large-Scale Gully Erosion Modeling: Challenges and Solutions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4311, https://doi.org/10.5194/egusphere-egu26-4311, 2026.
Vegetation plays a crucial role in the control of gully erosion due to its combined impact of root system and the above ground components. However, limited research has been done on the hydrodynamic effects of vegetation in relation to gully erosion. Vegetation, including stems and litter, are key surface roughness factors that greatly influence the flow of water, subsequently impacting sedimentation. In this study, a series of scouring experiments were conducted to investigate the effects of different shrub stem coverages (0%, 0.15%, 0.30%, 0.60%, and 1.20%) and litter coverages (0 g m-2, 100 g m-2, 200 g m-2, 300 g m-2, and 400 g m-2) on the spatiotemporal variations of flow velocity, shear stress, resistance f and sediment concentration under concentrated flow during the gully bed erosion processes in the dry-hot valley region of Jinsha River, Southwest China. The results showed that the number of branches in the vegetated plots increased significantly from upstream to downstream as stem coverage and litter coverage increased. Compared with bare gully bed, the flow velocity and shear stress of the four stem coverages decreased by 17% ~ 61% and 2% ~ 23%, respectively. These reductions were more significant as stem coverage and litter accumulation increased. The resistance f increased 0.14~5.8 times as stem cover and litter coverage increased, and the increase was more obvious along with the extending direction of gully bed. The sediment concentration decreased with increasing stem cover and litter coverage. The split flow effects under different shrub stem and litter coverages significantly affected the spatiotemporal variation of soil loss and hydraulic properties during gully bed erosion processes. Overall, increasing shrub planting in gully beds is essential to mitigate gully bed erosion, and the effects generally are enhanced with increasing stem litter and cover in gully beds.
How to cite: Xiong, D. and Liu, L.: Hydraulic properties and sediment yield as affected by different shrub stem and litter coverages during gully bed erosion processes , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4418, https://doi.org/10.5194/egusphere-egu26-4418, 2026.
Within the historically cultivated region of Navarra, Spain, ephemeral gully erosion dominates soil losses, threatening agricultural productivity and landscape degradation. Effective management requires soil erosion prediction technology as directly informed by regionally collected field data. In particular, soil erosion models must replicate the emergence and evolution of ephemeral gullies in time and space to accurately assess and implement conservation practices. Here we report on the results of a field campaign located in Pitillas, Southern Navarra. An agricultural field composed of a highly erodible silty loam was tilled in November 2023, but it was kept out of production for the 2023-24 growing season. The evolving landscape was captured by drone flights after every major precipitation event, producing DEMs at centimeter-scale resolution. Ephemeral gullies appeared four months after initial tilling, which over time created incised drainage network systems. Centimeter-to-decimeter scale rills occupy the furrows that are concordant to the tilled topography, whereas decimeter-scale ephemeral gullies occupy the major swales that are discordant to the tilled topography. One such rill and ephemeral gully system at the conclusion of the season is interrogated to define the morphometric characteristics of the eroded channels and to calculate total soil losses. This third-order ephemeral gully system exhibits a trellis drainage pattern occupying an area of 0.266 ha. Channel dimensions and longitudinal profiles are characterized along nine continuous channel reaches. The results show that scaling relationships for channel width and depth conform well to upstream drainage area using a hydraulic geometry framework. Exponent values derived for the longitudinal variation in width, average depth, and maximum depth as a function drainage area are 0.21±0.06, 0.31±0.11, and 0.34±0.11, respectively. That is, these channels incise more deeply than they widen in response to erosive runoff events consistent with previous observations within the region. While variations in slope concavity indicate localized zones of flow acceleration and deceleration, a headward migrating wave of degradation, located mid-slope by season’s end, demarcates the transition from areas of net erosion to net deposition. By comparing original and final surface topographies, total soil loss from this ephemeral gully system is estimated to be 3.23 kg/m2-yr, also consistent with previous work in this region. Current efforts are now focused on (1) correlating specific rainfall events to channel development and evolution, and (2) validating models to ensure that these discrete erosional processes can be predicted accurately in time and space. The field campaign has proven to be invaluable in the further development and refinement of soil erosion prediction technology required for effective resource management regionally.
How to cite: Bennett, S. J., Barberena, I., Campo-Bescós, M. A., van Wiltenburg, K., and Casalí, J.: Using a natural field experiment to characterize the temporal and spatial evolution of ephemeral gully erosion on a conventionally tilled plot, Southern Navarra, Spain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8002, https://doi.org/10.5194/egusphere-egu26-8002, 2026.
Abstract:
Gully erosion is a critical threat to global food security. Under intensive cultivation and increasingly frequent extreme rainfall, many ephemeral gullies (EGs) are rapidly evolving into permanent gullies. However, compared to permanent gullies, the impacts of EGs remain poorly understood. In particular, the effects of EGs on upland crops' growth and yield have been widely underestimated.
As EGs are often masked by seasonal tillage, they commonly exhibit pronounced dynamic changes and delayed effects. EGs’ development not only accelerates soil erosion but also significantly reshapes the spatial distribution of soil structure, moisture, and nutrients. These impacts extend from the gully channel into adjacent areas. Conventional assessments commonly attribute yield decline to soil loss, overlooking the constraints imposed by EG-induced soil compaction and root habitat degradation. Consequently, the real contribution of productivity loss induced by EGs remains obscured.
To address these knowledge gaps, this study focused on ephemeral gullies in croplands of the Black Soil Region of Northeast China. Integrating field survey and UAV-based high-resolution imagery, we measured the morphological parameters of typical EGs and their actual damage to arable land. Through experimental analysis, we evaluated the soil structure, moisture, nutrients, crop growth, and crop yield at 108 independent sampling points within EG-controlled catchments. Our results demonstrate that EG development significantly intensifies soil compaction, reduces soil water-holding capacity and nutrient availability, and ultimately suppresses crop growth and yield. Structural Equation Modeling (SEM) further reveals the influence pathways of "gully→topography→soil properties→crop response" in slope-gully systems.
This study clarifies the key processes through which gully erosion drives yield loss and emphasizes the necessity of EGs-controlled slope-gully systems as priority conservation and management units. Such an approach is crucial for improving land degradation assessment frameworks, mitigating permanent gully risks, and protecting regional food security.
Keywords: Ephemeral gully; Yield loss; Soil physicochemical properties; SEM; Slope-gully systems
How to cite: Qiao, X., Wang, C., Wang, W., and Ma, L.: The Overlooked Impact of Ephemeral Gullies on Arable Land Degradation: From Soil Physicochemical Transformation to Yield Loss, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9838, https://doi.org/10.5194/egusphere-egu26-9838, 2026.
Subsurface erosion caused by soil piping is of the most overlooked soil erosion processes. It plays a significant role in landscape development (including gully development) and contributes substantially to land degradation. Moreover, soil pipes affect hydrological and sediment connectivity in landscapes and hence potentially aggravate off-site effects of water erosion. Since now, the global distribution of this process remains unknown, as existing publications present only case studies and lack regional or global overview. This presentation aims to demonstrate the potential of Google Earth imagery for detecting pipe collapses (PCs) worldwide. The methods include manual on-screen mapping of PCs in different morphoclimatic zones and under various land use types (e.g., arable lands, pastures). Preliminary results indicate that Google Earth can be successfully used for detecting PCs. Its main advantages are the ease and wide accessibility of the software. Additionally, Google Earth imagery allows analyses of temporal changes in PCs where images from different years are available. The principal limitations are associated with forested areas, where PCs are sometimes observed. This limitation can be overcome by analyzing LiDAR-derived digital elevation models. However, these data are not as readily or universally available as Google Earth imagery.
The study is supported by the National Science Centre, Poland within the project OPUS 29 (2025/57/B/ST10/01326).
How to cite: Bernatek-Jakiel, A.: Google Earth imagery as a tool for detecting pipe collapses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10192, https://doi.org/10.5194/egusphere-egu26-10192, 2026.
Gully gravitational erosion is one of the primary erosion types on the Loess Plateau and an important pathway for sediment yield in watersheds. To address the challenges of the complex gravitational erosion process and the difficulty in observation and identification, this study analyzes the environmental conditions, locations, scales, and types of gravitational erosion on the Loess Plateau. Leveraging existing observation technologies and data processing capabilities, a multi-technology integrated observation method for gravitational erosion is developed through the functional synergy of various observation techniques. This method offers broader observation coverage, faster data processing, and higher precision in monitoring processes, providing a scientific basis for soil and water conservation efforts on the Loess Plateau.
How to cite: Zhang, P.: Characteristics and Observation Methods of Gully Gravity Erosion on the Loess Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11557, https://doi.org/10.5194/egusphere-egu26-11557, 2026.
Gully erosion is a significant soil erosion process with potentially severe on-site and off-site impacts. Characterizing and monitoring gullies is essential for accurately predicting their occurrence and effectively preventing their formation and extension. However, creating a gully inventory is both time-consuming and subject to operator bias. Given the low spatial density of gullies in most contexts and their sometimes ephemeral nature, the use of remote sensing appears unavoidable.
In Wallonia (Belgium), gullies mainly occur as ephemeral gullies on agricultural land. Their average width could be as small as 50 cm. High-resolution (25 cm) orthophotographs covering the entire territory are acquired on an annual basis and freely available. Although gullies mostly form on bare or poorly covered soil, depending on the dates of gully formation and image acquisition, gullies may be surrounded by bare or vegetated soil.
As of today, no methodology has been developed for automatically detecting gullies with such small dimensions at regional scale. This study therefore aims at developing a methodology for automatically detecting ephemeral gullies in Wallonia by remote sensing.
Based on June 2019 orthophotos, 67 gullies across 32 agricultural plots with varying soil cover (including bare soil) were digitized. 16 plots (34 gullies) were used for calibration and 16 plots (33 gullies) for validation. Gully and non-gully pixels were defined inside and immediately outside each gully, respectively, while accounting for delineation uncertainty. An optimal NDVI threshold for each gully was defined as the value maximizing the F1-score of the confusion matrix.
Three pixel-based classification approaches were considered: (1) a fixed NDVI threshold, set to maximize the average F1-score across all gullies of the calibration dataset; (2) a plot-specific NDVI threshold derived from a regression equation linking the median NDVI of the agricultural plots to their optimal NDVI thresholds. This equation was established to optimize the average F1-score (0.82); and (3) a multi-variable Random Forest model.
The use of a fixed NDVI threshold (NDVI = 0.13) achieved an F1-score of 0.77 on the validation dataset. Proper gully detection was achieved only when the median NDVI value of the plot exceeded significantly the threshold value. In contrast, the variable thresholding method allowed to detect gullies even on plots with median NDVI values as low as -0.017 (validation F1-score = 0.82). However, below this value, it failed to detect gullies reliably.
The Random Forest model (3) was trained on the same database. Additional remote sensing as well as topography-related variables were included, such as brightness, the Maximum Difference Index (the maximum difference between the RGB and NIR bands for each pixel), and the distance to the nearest concentrated runoff flow path. Preliminary results are encouraging, and combining this approach with the relative thresholding method could facilitate scaling detection to agricultural plot level and improve post-processing of features with spectral characteristics similar to gullies (e.g., wheel tracks). This approach shows strong potential for large-scale monitoring of gully erosion.
How to cite: Weber, A. and Bielders, C.: Automatic Detection of Ephemeral Gullies Using Orthophotographs: Development and Comparison of Three Pixel-Based Methods in Wallonia (Belgium), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12886, https://doi.org/10.5194/egusphere-egu26-12886, 2026.
Whereas current erosion models are successful in quantitative estimates of soil erosion by water flow, modeling the coevolution of geomorphological features, particularly rill network properties and soil erosion on hillslopes, is still a major challenge. In this study, we propose a rill evolution modeling approach, and combine it with a rainfall-runoff and soil erosion model to simulate the feedback loop of hillslope geomorphic development and soil erosion processes. Rill evolution is mainly characterized by three rill network attributes, comprised of rill density, orientation angle, and rill width, all modeled with physical equations. The entire rainfall-runoff-erosion and rill evolution model is tested against a set of rill network evolution and soil erosion data from an experimental hillslope subjected to successive rainfall events. The simulated spatial and temporal variations of rill network characteristics and soil erosion agree well with the measured data. The results demonstrate that the three rill network characteristics continually alter the partitioning of interrill and rill flows and affect the interrill and rill flow erosivity and soil erosion, which in turn modify the rill geometry and rill network planform. Comparatively, existing approaches such as WEPP that ignore the rill evolution processes largely underestimate the hillslope soil erosion when using time independent model parameters. Moreover, a sensitivity analysis indicates that both the rill evolution and soil erosion processes are sensitive to the rill evolution parameters, rainfall intensity, and slope angle. These results can inform the development of general geomorphic evolution and soil erosion models on evolving rilled hillslopes.
How to cite: wu, S.: Modeling soil erosion with evolving rills on hillslopes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15441, https://doi.org/10.5194/egusphere-egu26-15441, 2026.
The Northeast Black Soil Region is a crucial commercial grain production base in China. However, long-term intensive mechanized farming combined with a lack of effective soil and water conservation measures has resulted in severe soil erosion driven by the combined effects of wind erosion, water erosion, and freeze-thaw processes, critically threatening both food security and ecological stability. Farmland shelterbelts are widely recognized as an effective measure to reduce wind speed through surface friction and turbulence generation, and thus play a key role in decreasing wind erosion and improving soil properties. Nevertheless, their layout and orientation have rarely considered potential impacts on water erosion processes, and the role of shelterbelt distribution in regulating rill/inter-rill erosion, and gully erosion remains poorly understood. In our study, the effects of shelterbelt arrangements on both wind and water erosion were systematically assessed in the typical black soil region of Northeast China using field sampling surveys and multi-temporal remote sensing interpretation, integrated with meteorological and topographic data. The results indicate that shelterbelts effectively control wind erosion, with particularly better effects in areas experiencing severe wind erosion. However, shelterbelt orientation on sloping croplands often constrains ridge direction, and when tillage shifts to up- and down-slope or cross-slope ridging, rill and gully erosion are significantly enhanced. In addition, snowmelt runoff is a major driver of water erosion in high-latitude regions. Shelterbelts influence snow redistribution patterns, thereby modifying snowmelt-driven runoff and soil erosion processes. Gullies affected by shelterbelt-induced snow redistribution exhibited area expansion rates approximately 1.6 times higher than those unaffected. These findings provide new insights into the coupled effects of shelterbelt configuration on wind and water erosion and offer a scientific basis for optimizing shelterbelt design and soil erosion control strategies in cold-region agricultural landscapes.
How to cite: Tang, J., Xie, Y., and Cheng, H.: Can farmland shelterbelts exacerbate soil erosion in the black soil region of Northeast China?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16915, https://doi.org/10.5194/egusphere-egu26-16915, 2026.
Loess covers approximately 10% of the Earth’s land surface. Despite its ability to maintain vertical cliffs, loess is highly susceptible to rapid internal erosion, leading to the formation of pipes, tunnels, and gullies. These in turn can lead to ground collapse or rapid transport of contaminants. Despite these impacts, the physical process of how these gullies form is not yet fully understood. Our contribution focuses on the effect of confinement, a critical factor for loess stability that has been so far understudied.
This study used a new experimental method where loess blocks were encased in concrete or epoxy to simulate deep-profile conditions. These laboratory simulations revealed a distinct dual behavior: unconfined loess disintegrates rapidly through air slaking upon contact with water, whereas confined loess—restricted from expanding by the surrounding soil mass—maintains its structural integrity and resists erosion even under high hydraulic pressure.
Field validation conducted at a quarry supported these findings. In situ tests demonstrated exceptional cohesion, withstanding hydrostatic pressures of up to 3 meters. The results show that loess collapse and pipe expansion are not continuous but occur only at the onset of flow through them. The results indicate that erosion in loess pipes and tunnels is driven by air-slaking when excess air pressure builds up in pores due to surface tension as water infiltrates previously air-filled pores, not by the seepage force of flowing water. This study shows that any credible experimental setup for cohesive soils must consider the effect of confinement to accurately reflect field conditions.
- Vojtíšek, J., Bruthans, J., & Weiss, T. (2025). Confinement as a key but overlooked factor controlling erosion rate in loess pipes and tunnels. Geomorphology, 109874.
- Vojtíšek, J., & Bruthans, J. (2024). Loess susceptibility to erosion: Interaction of cohesion sources, air slaking and confinement. Earth Surface Processes and Landforms, 49(6), 1821-1835.
How to cite: Weiss, T., Vojtíšek, J., Landa, D.-A., and Bruthans, J.: Confinement as a key factor in loess erosion and stability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17747, https://doi.org/10.5194/egusphere-egu26-17747, 2026.
Gully erosion is one of the most severe yet least systematically monitored forms of soil erosion in Europe, causing disproportionate losses of fertile soil, landscape fragmentation and significant off-site impacts. Despite its importance for agricultural sustainability and long-term soil security, gully erosion has historically been poorly represented in continental-scale monitoring frameworks, limiting its integration into policy-relevant assessments.
Here we present a pan-European analysis of gully erosion based on the 2022 Land Use/Cover Area frame Survey (LUCAS), which combined in situ field observations and on-screen interpretation across 399,591 locations in the European Union. This effort resulted in GE-LUCAS v1.1, the first harmonized EU-wide inventory of gully erosion channels, identifying 3,116 locations affected by gully erosion, corresponding to approximately 0.8% of all surveyed points. The inventory reveals strong spatial contrasts across Europe, with a clear predominance of gully occurrence in Mediterranean regions and substantially lower frequencies in northern and Atlantic areas. Gully presence shows consistent associations with land use and land cover, soil texture classes and biogeographical regions, underscoring the combined influence of climate conditions, topography and land management practices on gully development (Borrelli et al., 2025a).
In the second part of the contribution, we use Mediterranean olive groves as an illustrative example to demonstrate how these continental-scale patterns translate into acute threats to soil security at the landscape level. Recent evidence highlights that the expansion of olive cultivation onto steeper, erosion-prone terrain, combined with intensive management practices and increasing climate pressure, has led to widespread gully erosion and extremely high soil loss rates in key producing regions such as southern Spain, Italy and Greece. In these systems, gully erosion undermines the long-term availability of soil as a productive resource, amplifies off-site environmental impacts and increases socio-economic vulnerability in rural areas (Borrelli et al., 2025b).
Overall, this contribution demonstrates the value of harmonized large-scale monitoring for identifying gully erosion hotspots and land-use systems at risk, providing new evidence to support soil security objectives and targeted mitigation strategies under current and emerging EU soil policies.
Acknowledgement
Authors acknowledge funding from the European Union Horizon Europe Project Soil O-LIVE (Grant No. 101091255) and from the European Union’s NextGenerationEU project ‘Complex Modelling of Multiple Land Degradation Processes in Europe’ (EUroLanD), grant agreement ID 760051/23.05.2023, code CF 216/29.11.2022, under the National Recovery and Resilience Plan of Romania – Pillar III, Component C9-2022-I8.
References
Borrelli, P., Matthews, F., Alewell, C., Kaffas, K., Poesen, J., Saggau, P., & Panagos, P. (2025a). A hybrid in situ and on-screen survey to monitor gully erosion across the European Union. Scientific Data, 12(1), 755.
Borrelli, P., Matthews, F., Saggau, P., Manzaneda, A. J., Panagos, P., Kaffas, K., & Alewell, C. (2025b). Unsustainably losing ground. Nature Sustainability, 8(9), 986-989.
How to cite: Borrelli, P., Panagos, P., Pravalie, R., and Alewell, C.: Pan-European monitoring of gully erosion: spatial patterns, land-use controls and implications for soil security, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17961, https://doi.org/10.5194/egusphere-egu26-17961, 2026.
ABSTRACT: Soil erosion is a severe form of land degradation that threatens food production, especially in Northeast China, where fertile Mollisols dominate the agricultural landscape. Most previous studies have quantified soil erosion by water, while wind erosion of severely water-eroded areas with exposed loose subsoil remains rarely explored. Here, we present a wind tunnel experiment (75 measurements) with different wind velocities and aggregate size classes (<53, 53-250, 250-850, and 850-2000 μm) to assess the wind erosion behavior of loose subsoil. Free-stream wind velocities of 10, 12, 14, and 16ms-1 resulted in shear velocities ranging from 0.15 to 0.75 ms-1. The variation of shear velocity depended on the interaction between free-stream wind velocity and the surface roughness as influenced by aggregate size (R² = 0.40). The maximum aggregate size was also a good predictor of threshold velocity (R² = 0.84). Moreover, mass flux at higher elevations increased with wind velocity for both the 53-250 and 250-850 μm groups, whereas near-bed behavior varied by aggregate size. The second-finest fraction (53-250 μm) always exhibited an obvious peak in mass flux with height. The peak height increased slightly from 3 to 5 cm with increasing wind velocity. The second-coarsest fraction (250-850 μm) developed a pronounced peak height only at the highest wind velocity (16 ms-1). These wind tunnel experiments on sieved loose subsurface soil materials indicate potential wind-driven transport. They also demonstrate that sever water erosion may additionally increase wind erosion and should be avoided to safeguard soil resources and food security.
How to cite: Wen, Y., Xu, Y., and Auerswald, K.: Effects of Wind Velocity and Aggregate Size on Wind Erosion Characteristics of Loose Subsoil From the Mollisols Region of China: A Wind Tunnel Assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20282, https://doi.org/10.5194/egusphere-egu26-20282, 2026.
Soil erosion driven by soil compaction and freeze-thaw cycles is a critical global environmental issue in intensively mechanized cold-region agroecosystems. Existing studies predominantly focus on the direct effects of freeze-thaw cycles on soil erosion, yet overlook the legacy effects of pre-freeze-thaw soil compaction, particularly whether a critical threshold exists for such legacy effects. A comparative study was conducted in the Mollisol region of Northeast China by using in situ field erosion experiments and soil property measurements under various compaction levels before and after the freeze-thaw period. Results showed that the pre-freeze-thaw soil compaction exacerbated post-freeze-thaw soil erosion. Before the freeze-thaw period, the influence of soil properties on runoff was greater than their direct effect on sediment mass, and the sediment mass variation was mainly driven by runoff scouring due to soil compaction. After the freeze-thaw period, the decreased soil erosion resistance (aggregate stability and soil strength) and the increased runoff caused by the legacy effects of compaction were the primary reasons for higher sediment mass in compacted soil compared to uncompacted soil. Based on these findings, we propose a conceptual framework to determine a critical bulk density range that maximizes the alleviating effect of freeze-thaw cycles on soil compaction to reduce runoff, thereby avoiding the exacerbation of post-thaw soil erosion. This study underscores how compaction legacy amplifies post-thaw erosion, offering mechanistic insights into optimizing tillage management and soil restoration in seasonally frozen agroecosystems.
How to cite: Zhang, B., Maerker, M., and Ma, R.: Legacy effect of soil compaction drives post-freeze-thaw rill erosion: Identifying the critical hydro-mechanical threshold in Mollisols, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21211, https://doi.org/10.5194/egusphere-egu26-21211, 2026.
