Mountain watersheds, critical for water provisioning, biodiversity, and livelihoods, are increasingly vulnerable to a spectrum of natural hazards, including landslides, debris flows, glacial lake outburst floods (GLOFs), and extreme hydrological events. These hazards, often intensified by climate change and anthropogenic pressures, pose significant threats to ecosystem integrity, infrastructure, and human security downstream. Sustainable watershed management (SWM) emerges as a vital framework to mitigate these risks while preserving ecological functions and supporting socio-economic resilience. This study presents a comprehensive synthesis of research published over the past decade in the Journal of Mountain Science (JMS), a leading platform dedicated to mountain research.
Through a systematic review and thematic analysis of pertinent literature from JMS, we identify key research trends, knowledge clusters, and evolving paradigms at the intersection of mountain hazards and SWM. Our synthesis reveals three dominant thematic strands: (1) advanced methodologies for hazard monitoring, modeling, and risk assessment using remote sensing, numerical simulation, and community-based approaches; (2) analysis of hydro-geomorphic processes and their sensitivities to climatic and land-use changes; and (3) evaluation of integrated management strategies, such as ecosystem-based disaster risk reduction (Eco-DRR), green infrastructure, and adaptive governance models.
The analysis underscores a shift from purely technical hazard control towards more holistic, socio-ecological systems approaches. Key insights highlight the necessity of coupling engineering solutions with the restoration and conservation of watershed ecosystems to enhance natural buffering capacity. Furthermore, the synthesis identifies critical research gaps, including the need for long-term interdisciplinary studies, improved transboundary governance mechanisms, and strategies that explicitly link upstream hazard mitigation with downstream water security and equitable benefit-sharing.
This synthesis consolidates foundational knowledge from JMS, offering a consolidated reference for scientists, policymakers, and practitioners. It concludes that the sustainable future of mountain regions hinges on integrative science and policies that concurrently address hazard reduction, watershed protection, and sustainable development goals.
How to cite: Qiu, D.: Mountain Hazards and Sustainable Watershed Management: A Synthesis of Research Published in Journal of Mountain Science, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4318, https://doi.org/10.5194/egusphere-egu26-4318, 2026.
Soil and water conservation practices (SWCPs) are fundamental strategies for interrupting sediment connectivity and mitigating soil erosion at the watershed scale. However, traditional design approaches often overlook the spatial heterogeneity of sub-basins and the complex trade-offs between environmental benefits and economic costs. This study proposes a novel multi-objective optimization framework to identify optimal SWCP configurations that balance ecosystem service value (ESV), life-cycle investment costs (IC), and sediment yield reduction. Using the Soil and Water Assessment Tool (SWAT) coupled with a non-dominated sorting genetic algorithm (NSGA-III), we evaluated fifteen SWCP scenarios (combining terracing, contour farming, and check dams) . The results demonstrate that combined SWCPs significantly outperform individual measures in disrupting sediment transport, with the combination of terracing, contour farming, and boulder check dams achieving the highest reductions in sediment yield (SY). While higher investment costs generally correlate with greater sediment reduction, our optimization reveals that low-cost practices like contour farming provide efficient connectivity management despite lower ESV. The optimized solution identified in this study reduced SY by 4.496 × 105 t and streamflow by 36.84 × 105 m³ with a minimal IC of 4.61 × 106 CNY, effectively maximizing the cost-benefit ratio. These findings provide a scientific basis for sustainable watershed management, offering policymakers a tool to navigate the challenges of balancing erosion control, ecological restoration, and economic constraints.
How to cite: Zhang, S. and Li, H.: Optimizing Watershed Sediment Management: A Multi-objective Approach Balancing Erosion Control, Ecosystem Services, and Economic Costs, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8956, https://doi.org/10.5194/egusphere-egu26-8956, 2026.
Sediment connectivity provides a powerful conceptual and quantitative framework for understanding how water and sediment are transferred from hillslopes to channels and downstream receptors. Yet, its integration into practical watershed management remains limited, particularly in ungauged catchments where hydrological and sediment monitoring data are lacking. This study investigates how sediment connectivity can be utilized to identify critical sediment source–pathway–sink linkages that control the emergence of sediment-related management issues and indicate where management interventions are most effective for mitigating risk across diverse landscapes in the Czech Republic.
We analyzed sediment connectivity in three types of ungauged catchments representing key management contexts: (i) forested mountain headwaters affected by historical torrent control works, (ii) forested tributary catchments contributing sediment to the Dyje/Thaya River within the Podyjí/Thayatal National Park, and (iii) small agricultural catchments exposed to torrential rainfall and severe soil erosion. Across all sites, field-based mapping of sediment sources, buffers, and barriers was combined with GIS-based connectivity metrics, particularly the Index of Connectivity (IC) and the Effective Catchment Area (ECA). In agricultural catchments, these approaches were further integrated with process-based erosion modelling (WEPP and GeoWEPP) and validated using UAV-derived measurements of event-scale soil loss. The results indicate that management-relevant sediment dynamics emerge from the interaction of structural and functional connectivity rather than from static landscape properties alone. In forested headwaters, roads and torrent control structures act as barriers and buffers, reducing hillslope–channel and longitudinal connectivity. This allows critical sediment delivery zones and sediment-fed reaches to be identified. In protected, dam-fragmented catchments, the abundance of sediment sources and high structural connectivity do not result in effective sediment delivery, as large woody debris, small dams, and floodplain storage interrupt sediment transfer. In agricultural catchments, IC-derived flow paths closely match observed erosion patterns, and land-use scenarios demonstrate that the targeted placement of grass strips or low-erosion crops can substantially reduce sediment connectivity, erosion risk, and the downstream transfer of sediment during extreme rainfall events. Overall, the study shows that sediment connectivity offers a unifying and transferable framework for linking sediment sources, pathways, and impacts across diverse environments. When combined with field observations and erosion modelling, connectivity mapping supports the identification of critical reaches, disconnections, and hot spots and provides guidance for targeted, landscape-based mitigation of sediment-related issues in data-poor catchments.
How to cite: Koreňová, S., Šulc Michalková, M., Pöppl, R., Bachan, R., Máčka, Z., Holiš, D., and Stará, E.: Sediment connectivity as a decision-support framework for sustainable management of ungauged catchments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18012, https://doi.org/10.5194/egusphere-egu26-18012, 2026.
Understanding how bed roughness modulates hydrodynamic processes around vegetation is critical for predicting soil erosion patterns in sloped landscapes. Through flume experiments with high-frequency particle image velocimetry (PIV), this study quantifies the interactions between bed roughness (ks=0.009, 0.25, 0.75,1.55) and horseshoe vortex (HV) dynamics under shallow overland flow conditions (ReD=2627-3815). Time-averaged flow field analysis, based on vorticity and swirl strength methods, revealed that increasing surface roughness disrupted the HV system by reducing the number of vortices, decreasing the vorticity and swirl strength of the primary HV, and shifting its position closer to the bed. Statistical analysis of the instantaneous velocity components showed the emergence of bimodal probability density functions (PDFs) and joint probability density functions (JPDFs) in the near-wall region upstream of the cylinder, representing the backflow and downflow events. As roughness increased, the bimodal region decreased in size and shifted further from the cylinder. Linear Stochastic Estimation (LSE) was used to characterize the underlying flow modes, indicating that the backflow event was associated with the backflow mode, while the downflow event was linked to the zero-flow mode. Notably, roughness elements enhanced flow stagnation (zero-flow mode dominance >60%), suggesting a potential mechanism for erosion mitigation. These findings provide quantitative linkages between micro-scale hydrodynamics and landscape-scale erosion processes, informing the design of vegetation-based erosion control strategies through targeted roughness manipulation.
How to cite: Zhang, H., Gu, F., Xia, S., Li, F., Wang, L., and Zhang, D.: Role of Micro-dynamic structures in the process of water erosion under complicated underlying surface conditions , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2688, https://doi.org/10.5194/egusphere-egu26-2688, 2026.
Accurately identifying critical soil erosion source zones and sediment transport pathways within watersheds represents a key challenge in current soil erosion control and watershed management. To address this challenge, an integrated "RUSLE-IC" analytical framework was developed in this study, coupling the Revised Universal Soil Loss Equation (RUSLE) with an improved Sediment Connectivity Index (IC) to systematically quantify the spatial correspondence between erosion and transport processes. In this study, we utilized high-resolution UAV remote sensing techniques in a typical red soil hilly watershed in southern China. Based on calculated soil erosion modulus, and the sediment connectivity index was revised by integrating topography, vegetation, and road-ditch-pond artificial network elements. Additionally, the four-quadrant method was utilized to analyze the spatial matching patterns between erosion modulus and connectivity levels, thus accurately identifying the critical “source-pathway-sink” zones for sediment transport within the watershed. The results indicated that: (1) The predominant soil erosion level in the watershed was slight (75.43%), but the light erosion level, which accounted for only 23.50% of the area, contributed 60.03% of the total soil loss in the watershed, demonstrating highly spatially concentrated erosion. (2) The IC was significantly enhanced by the effects of road and ditch-pond networks, which combined to contribute 58.82% of the total IC enhancement effect. Meanwhile, a distance-threshold decay in the effect was observed, where the IC values decreased significantly with increasing distance within a 40-meter buffer zone (R²>0.91), but the effect weakened beyond that range. (3) The coupled erosion-connectivity analysis revealed that high erosion–high connectivity (HE-HC) zones, which comprising only 6.34% of the watershed area, contributed 25.76% of sediment yield and were identified as priority areas for management. And low erosion–high connectivity (LE-HC) zones (11.81%), predominantly associated with roads, ditches, and ponds, were characterized as potential high-efficiency sediment delivery pathways. Generally, (4) sediment transport in small watersheds was more sensitive to soil erosion source areas than to high-connectivity zones. The effectiveness of the proposed framework for identifying soil erosion and sediment delivery hotspots under complex surface conditions was validated, providing a scientific basis for implementing targeted soil and water conservation measures based on coordinated regulation of “source areas and transport pathways.”
How to cite: Li, P., Zhao, H., and Qi, S.: The Role of Road and Ditch-Pond Networks in Regulating Sediment Connectivity: An Analysis of the “Source-Pathway” Relationship of Sediment in Subtropical Red Soil Hilly Watersheds from an Erosion-Connectivity Coupling Perspective, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2797, https://doi.org/10.5194/egusphere-egu26-2797, 2026.
Sediment connectivity governs sediment dynamics in large river basins by linking erosion sources to delivery sinks, yet remains underexplored across Himalayan–orogenic to cratonic transitions where upstream pulses encounter downstream impedance. This study analyzes spatiotemporal connectivity and hotspot dynamics in the Yamuna basin’s transitional hinterlands, integrating contrasting Himalayan Upper Yamuna and cratonic Chambal ravine–badland sub-basins using a modified Index of Connectivity (IC) that combines structural (topographic slope, NDVI roughness) and functional (rainfall) controls for annual and monsoonal (June–October) conditions over 1999–2005. The Upper Yamuna exhibits the highest, most coherent connectivity (annual mean IC ≈ −8.64 versus −8.68 in Chambal), due to higher slopes and rainfall intensity, with persisting hotspots occupying ~20% of the basin and concentrated in the upper–middle Himalayan reaches. However, the ~750 km reach of the Yamuna River between the SubHimalaya to its confluence with the Chambal River is largely coldspot dominated, so sediment released from upland persisting hotspots experiences prolonged routing and storage, and only a modest fraction reaches the outlet. In contrast, the Chambal ravine–badland basin has slightly lower, more fragmented connectivity but far more dynamic hotspots, with new and sporadic classes occurring at ~10× the frequency seen in the Upper Yamuna and total hotspot–coldspot area ~50% larger. Persisting hotspots in the ~550 km long Chambal valley form a nearly continuous belt, spreading ~20–100 km from the trunk stream. These proximal, highly connected badland patches drastically shorten travel distances and reduce buffering, so monsoonal erosion pulses are efficiently transmitted to the gauge, with mean discharge about three times and mean sediment load about nine times higher than at the Upper Yamuna station, despite the lower basin-averaged IC of the Chambal basin. Together, these patterns show that the location, persistence, and river-parallel extent of connectivity hotspots relative to outlets can outweigh basin-averaged connectivity in controlling measured sediment loads, highlighting cratonic ravines as intermittent sediment sources that can rival or exceed Himalayan contributions. These findings also underpin a scalable structural–functional IC framework for tailored sediment management in Himalayan - cratonic river systems and analogous anthropogenically altered rivers worldwide.
How to cite: Dubey, P., Jain, V., and Singh, M.: Geomorphic Variability and Sediment Connectivity in a Transitional Himalayan - Cratonic River Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3032, https://doi.org/10.5194/egusphere-egu26-3032, 2026.
Effective water resources management in arid inland river basins is paramount for sustaining ecosystem health and socio-economic development. These basins face severe challenges due to climate change and intensive anthropogenic activities. This study addresses this challenge by developing a novel multi-level (regional, irrigation district, and field-scale) and multi-objective optimization model for water resources allocation in a typical inland river basin of Northwest China. Our approach explicitly incorporates the hydrological connectivity from upstream runoff to downstream consumptive use. We first simulate the available water yield from upstream mountain sources, which serves as the key driver of the basin's water cycle. The model then optimizes cropping patterns using ecological sustainability indicators (e.g., ecological water demand, carbon footprint) to enhance the functional linkage between water use and ecosystem health. A significant innovation of our work is the nested optimization framework that propagates decisions from the regional scale down to the field scale, effectively managing the vertical connectivity in watershed management hierarchies. Furthermore, we employ interval fuzzy programming to handle inherent uncertainties in water supply and demand, ensuring the robustness of the configuration schemes. The results demonstrate that our model can effectively balance economic, social, and ecological objectives, providing Pareto-optimal solutions for decision-makers. Finally, a user-friendly Decision Support System (DSS) has been developed to visualize the outcomes and facilitate the practical application of our research. This DSS provides managers with critical insights into the timing, location, and strategies for water allocation, thereby bridging the gap between connectivity science and on-the-ground watershed management. Our study offers a transferable framework for achieving sustainable water resources governance in data-scarce, water-stressed arid regions.
How to cite: Zhang, F.: Bridging Scales for Sustainable Watershed Management: A Multi-level Water Resources Optimization Framework for Northwest China's Inland River Basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-145, https://doi.org/10.5194/egusphere-egu26-145, 2026.
The northwestern arid regions of China (NARC) is widely confronted with severe water scarcity, and climate change has further intensified the regional imbalance between water supply and demand. To improve the management and utilization of limited water resources in NARC, it is essential to investigate the spatial distribution and temporal variability of water resources. In this study, we used a distributed hydrological model (CWatM) to examine spatiotemporal changes in terrestrial water storage (TWS), surface water area (SWA), and groundwater storage (GWS) over 1979-2023, and to identify the key drivers of storage variations. The results show that: (1) Based on the surface water areas of major lakes, reservoirs, and rivers in the arid region of Northwest China, SWA exhibited an increasing trend during the study period (32.1 km² yr-1), mainly attributable to increased precipitation and glacier melt. In contrast, TWS and GWS decreased at mean rates of 1.21 and 1.05 mm yr-1, respectively, primarily associated with cropland expansion and rising water withdrawals. (2) From 1979 to 2023, SWA declined in the northern subregion (−0.72 km² yr-1) but increased in the southern sub-region (51.14 km2 yr-1); this contrast is explained by differences in regional precipitation and temperature changes. Over the same period, TWS decreased by 0.14 mm yr-1 in northern NWC and by 1.94 mm yr-1 in southern NARC, while GWS declined by 0.55 mm yr⁻¹ in northern NARC and by 1.72 mm yr-1 in southern NARC. These north-south disparities are likely related to higher evapotranspiration and greater irrigation water use in southern NARC compared with the north. Overall, these findings are critical for improving our understanding of hydrological-cycle changes in NARC and for informing future watershed-scale water resources management strategies.
How to cite: Zhao, J. and Liu, W.: Spatial and Temporal Distribution of Water Storage Changes in Arid Regions of Northwest China under Climate Change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6338, https://doi.org/10.5194/egusphere-egu26-6338, 2026.
In arid environments, farmland shelterbelts are essential for harmonizing limited water resources with ecological and agricultural expansion. These systems function as critical protective barriers that enhance environmental stability and crop productivity by curbing aeolian erosion and refining local microclimates. However, the transition in irrigation techniques has diminished lateral seepage, leading to intensified water stress and heightened risks of shelterbelt degradation. Current spatial planning often fails to sufficiently integrate hydrological equilibrium with habitat suitability. To address this research gap, this study develops a multi-objective framework for spatial afforestation. The approach couples the SWAT distributed hydrological model with a vegetation-specific water demand simulation to evaluate the establishment potential of Populus alba var. pyramidalis. Two distinct irrigation regimes—traditional border irrigation and low-pressure pipe irrigation—were simulated to compare their impacts on afforestation capacity. The results indicate that evapotranspiration represents the primary component of water consumption, followed by surface runoff and lateral flow. The findings reveal a spatial gradient in afforestation potential, which decreases progressively from the central irrigation districts toward the desert peripheries. Under traditional irrigation regimes, agricultural intensification zones can support a higher tree density, whereas the transition to low-pressure pipe irrigation necessitates an adjustment in the optimal density range. These outcomes provide a scientific foundation for coordinating water allocation between forestry and agriculture, refining shelterbelt configurations, and fostering long-term ecological sustainability in water-limited regions.
How to cite: Ren, Y., He, X., Jiang, Q., and Zhang, F.: Optimizing the Spatial Configuration of Farmland Shelterbelts in Arid Oases under Hydrological Constraints: A SWAT-Based Scenario Analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11373, https://doi.org/10.5194/egusphere-egu26-11373, 2026.
Conducting experiment is an important means to study the regularity and control measures of soil erosion. This study presents a new subject, EXPERIMENTAL EROSION, as a member of the discipline of soil and water conservation. Experimental Erosion is defined to explore the transportation law and control method of soil and water loss by performing field or laboratory tests under closely monitored or controlled experimental conditions. The similarity theory, simulation and observation technology, and data processing method are the three pillars of the experimental erosion. In spite of the significant problems associated with the design and prosecution of experimental studies of soil conservation, the experiments can provide an insight into landform evolution and dynamics that can be obtained in no other way. This study develops new data sets and experimental methods to quantify the dynamics of soil loss that represent different stages in the development of soil functions. In conclusion, application of the new data tests how simulation and observation can be coupled to guide beneficial intervention in soils in order to control soil erosion, especially that on the steep slope.
How to cite: Xu, X.: Experimental Erosion: theory and practice of soil conservation experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11311, https://doi.org/10.5194/egusphere-egu26-11311, 2026.
Although previous studies have explored the effects of vegetation restoration and terrace construction on hydrological erosion processes, few studies have scientifically evaluated the regulation of runoff and sediment by different measures from the perspective of hydrological-sediment connectivity. In this study, field in-situ rainfall simulation experiments were conducted in combination with 3D laser scanning technology. Simplified hydrograph and relative surface connection function were utilized to characterize hydrological connectivity, while the index of connectivity (IC) was used to characterize sediment connectivity. Four measures configurations (i.e., terrace plot (Measure A), root system plot (Measure B), upper terrace and lower bare land plot (Measure C), upper terrace and lower root system plot (Measure D)) were set up. We explored the connectivity changes of vegetation and terrace patches, as well as the transport of runoff and sediment at the plot scale. Results showed that measure B has the lowest hydrological connectivity, and measure D has the lowest sediment connectivity. The transport of runoff and sediment mainly occurred in rills, and the connectivity within rill channels was much higher than that between rills. Compared with sediment, runoff responds more quickly to changes in sediment connectivity. In addition, measures A and B did not synchronize with changes in connectivity. The erosion process of integrated measure D was mainly divided into two stages. The first half depends on hydrological connectivity, while the second half relies on separation control. During continuous rainfall, the runoff reduction rate (RRE) and soil erosion reduction rate (SRE) of measure D were not the highest, but compared with other measures, its sediment connectivity reduction rate (ICRE) was as high as 12.1% ~ 12.3%. Therefore, we suggest that implementing comprehensive measures such as upslope terrace construction and downslope vegetation restoration can lead to better soil and water conservation outcomes.
How to cite: Ren, Z., Ma, X., Xu, G., Gao, H., Cheng, Y., wang, K., and Li, Z.: Evaluation of runoff and sediment control by different measures from the perspective of hydrological-sediment connectivity on the Loess Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7254, https://doi.org/10.5194/egusphere-egu26-7254, 2026.
Elements are the indelible imprint left by the Earth on rivers and life entities. Here, we unveil the evident inheritance of persistent elements, from the Earth's upper continental crust, through the Yellow River, to the associated life entities along a 5,200 km continuum of the Mother River of the Chinese nation. In particular, we confirm the coherence of “metal community” composed of more than 60 detected metallic elements throughout water, suspended particulate matter, and sediment in the river, and further extend such elemental correlations to fish species and even the tissues in human body. Our study also reveals an interesting fact that media-specific metal abundance occurs in a persistent inverse order with metal toxicity, and microbial cells in the river tend to establish their own self-defense systems against toxic metals through hosting higher-level resistance genes. These findings not only stress the human needs for integrated trace element provision, but also highlight the fundamental importance of elemental coherence in the river-coordinated Earth-life systems for establishing drinking water and dietary standards that benefit ecological and human health.
How to cite: Wang, Y.: Key to the Yellow River's Material Cycle and Implications for River Basin Management, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16154, https://doi.org/10.5194/egusphere-egu26-16154, 2026.
Vegetation restoration serves as a crucial strategy for regulating sediment connectivity and enhancing carbon sequestration in ecologically fragile watersheds. However, accurately quantifying the spatial relationship between vegetation restoration and sediment connectivity presents a critical challenge for sustainable watershed management, particularly in assessing the efficacy of ecological engineering in targeting areas at high risk of erosion.
This study utilizes the Huangshui River Basin—a representative hydro-geomorphological transition zone between the Qinghai-Tibet Plateau and the Loess Plateau of China as a case study. It employs multi-source remote sensing data spanning from 2001 to 2023, the Index of Connectivity (IC), and interpretable machine learning techniques (XGBoost-SHAP) to explore the interconnections between carbon dynamics and hydro-geomorphological processes.
Over the past two decades, the basin has exhibited a significant "greening" trend, with Net Primary Productivity (NPP) increasing at an average rate of 2.83 gC·m-2a-1. Utilizing the Geographical Detector and XGBoost-SHAP model, we identified temperature as the primary non-linear driving factor (q=0.68). Land-use change decomposition reveals that growth improvements in stable vegetation contributed over 85% of the net NPP increment, while ecological engineering projects contributed a net increment of 0.14 TgC through the conversion of marginal croplands. Incorporating sediment connectivity index, the study further revealed a non-linear interaction between geomorphology and vegetation, wherein carbon sink gains across different vegetation types initially increased and subsequently decreased with escalating erosion risk (IC). Distinct restoration thresholds were identified for cropland (IC peak at -5.9), grassland (-6.1), and shrubland (-5.6). Forests demonstrate remarkable adaptability to environments characterized by high connectivity, sustaining elevated levels of productivity even in geomorphologically unstable regions. The spatial synergistic patterns further reveal that areas characterized by "high risk-high restoration" are predominantly concentrated in the fragmented gullies and steep slopes located in the central and eastern parts of the basin.
This research confirms that anthropogenic restoration measures have been effectively targeted the key source areas of the watershed. In contrast, areas characterized by "low risk-high restoration" areas are widely distributed across the western alpine meadows, reflecting climate-driven natural recovery processes. These findings provide crucial insights for spatially differentiated governance, suggesting that future strategies should prioritize maintaining the stability of high-connectivity forests while addressing the anthropogenic challenges faced by urban agglomerations in valley regions.
How to cite: Ma, D., Gong, M., Hui, Y., and Yu, Y.: Vegetation Restoration–Sediment Connectivity Coupling in an Ecologically Fragile Transitional Landscape: Insights for Watershed Management, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10811, https://doi.org/10.5194/egusphere-egu26-10811, 2026.
As climate change accelerates, understanding the mechanisms of ecosystem phenology in vulnerable regions is crucial for terrestrial environments. This research systematically used remote sensing data to study the dynamic changes in vegetation phenology in the upper and middle Yellow River Basin (UMYRB), examined the effects of environmental shifts on vegetation phenology, and quantified the contributions of different driving factors. The key findings are as follows: (1) As elevation and latitude increase, the start of the growing season (SOGS) is generally delayed, particularly in the northwest and northeast, where it typically occurs between days 140 and 180. The end of the growing season (EOGS) shifts later from west to east, with 86.66% of the area experiencing EOGS between days 260 and 300. From 1981 to 2016, approximately 61.35% of the area exhibited a trend of advancing SOGS (-0.09 days/year), while 60.10% of the area showed a delay in EOGS (0.08 days/year). (2) Both SOGS and EOGS exhibit significant spatial variability influenced by climatic factors, with the primary pre-season impact period ranging from 1 to 4 months. SOGS is typically negatively correlated with precipitation and temperature, whereas EOGS often shows a positive correlation with precipitation and temperature. Temperature and solar radiation are the primary climatic drivers influencing vegetation phenology in the study region. Temperature accounts for 53.57% of SOGS and 50.73% of EOGS, advancing them by 0.18 and 0.22 days, respectively. Solar radiation also significantly influences SOGS and EOGS, advancing them by 0.14 and 0.13 days, respectively. While the impact of diurnal temperature range (DTR) and precipitation is less pronounced, DTR is notably important in high-altitude regions. (3) Vegetation phenology varies significantly across various vegetation types. Forests usually experience an earlier SOGS and a later EOGS, while shrubs in high-altitude areas tend to have a delayed SOGS due to a greater diurnal temperature range. The growing season of grasslands and wetlands is more significantly affected by precipitation and temperature, particularly in the eastern and northern regions. Solar radiation significantly impacts the entire growing season in croplands and grasslands in the central and southern regions. Uncertainty in vegetation phenology was assessed through Bootstrap analysis, and the spatial adaptability of climate driving factors was optimized using the ridge regression model. The results indicate that despite certain sources of uncertainty, the analysis demonstrates high accuracy and stability, providing a reliable scientific basis for ecological management and restoration.
How to cite: Yu, K., Li, X., Li, Z., Li, P., and Xu, G.: Spatiotemporal Evolution of Vegetation Phenology and Its Response to Environmental Factors in the Upper and Middle Reaches of the Yellow River Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16719, https://doi.org/10.5194/egusphere-egu26-16719, 2026.
Abstract: Rill erosion serves as a crucial transitional stage in water erosion, bridging sheet erosion and gully erosion, and constitutes a major form of soil erosion. Existing research has mainly focused on the impacts of vegetation patterns or vegetation coverage on rill erosion processes; however, the regulatory mechanisms of vegetation, terraces, and their combined configurations on rill erosion remain understood. To address this research gap, this study established slope-gully system models under six slope management scenarios: a control group (CK, bare slope), Measure A (upper-slope grass), Measure B (mid-slope grass), Measure C (lower-slope grass), Measure D (mid-slope terrace), Measure E (upper-slope grass + mid-slope terrace), and Measure F (mid-slope terrace + lower-slope grass). Employing simulated rainfall experiments and 3D laser scanning technology, this study clarified the developmental process of rill erosion and its responses to different management configurations, quantified variations in slope hydrological connectivity, and elucidated the regulatory mechanisms of different management measures on rill erosion. The results indicated that the combined Measure F exerted a significant regulatory effect on rill erosion processes in the slope-gully system. Specifically, this measure reduced the total rill length by 79.76%, delayed the initial occurrence of distinct rills by approximately 18 minutes, and minimized the average rill elongation rate to 1.32 cm/min. Additionally, it decreased the rill erosion mass, rill erosion volume, and the proportion of rill erosion by 50.14%, 50.06%, and 44.22%, respectively, exhibiting the optimal erosion control efficiency. Simultaneously, Measure F most effectively blocked surface runoff pathways, reducing the proportion of longer runoff path lengths by 4.99% and 4.81% compared to the control group after two rainfall events. Topographic analysis revealed that the slope topography was predominantly concave (characterized by negative skewness of the topographic convergence index), and the topographic wetness index increased post-rainfall, facilitating runoff generation. Compared with single measures, Measure F exerted a significant synergistic effect, enhancing the reduction rates of rill erosion mass, volume, and area by 18.82%, 20.51%, and 18.02%, respectively. In conclusion, the combined configuration of “mid-slope terrace + lower-slope grass” effectively inhibits rill erosion and optimizes slope hydrological connectivity, serving as an optimal integration of vegetative and engineering measures. This study provides a scientific basis for soil and water conservation management on the Loess Plateau.
How to cite: Bai, L., Shi, P., Zhang, Y., and Gao, Z.: Effects of combined vegetation and terrace configurations on rill erosion in the slope-gully systems of the Loess Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4715, https://doi.org/10.5194/egusphere-egu26-4715, 2026.
As a key soil and water conservation measure, check dams play an important role in erosion control, flood mitigation, and ecological restoration. Their scientific siting is the core prerequisite for realizing these composite benefits. To address the limitations of traditional siting methods, which are characterized by strong subjectivity, low efficiency, and incomplete multi-objective collaborative optimization, a multi-objective optimization framework integrating GIS, hydrological–hydrodynamic coupled models, and a genetic algorithm is proposed in this study. By parameterizing the distance from the watershed outlet (S) and the dam height (H), a continuous decision space is constructed, establishing quantitative mapping relationships with the dam crest length, sediment storage capacity, and silted land area. By coupling the HEC-HMS and HEC-RAS models, a flood surrogate model is developed to dynamically predict the peak flood reduction benefits under a 100-year flood scenario. Based on the Nondominated Sorting Genetic Algorithm II, a multi-objective optimization model incorporating the construction cost (C), peak flow attenuation (P), and sediment retention and farmland creation (SRFC) benefits (E) is constructed, revealing the nonlinear regulatory mechanisms of the decision variables on the objectives. A case study demonstrates that the optimal solution set significantly clusters in the middle and lower reaches of the Yangjiagou watershed (S < 4.2 km). High dams located near the outlet (S < 2.2 km and H > 20 m) correspond to schemes with strong flood-control performance (P > 60%) . Schemes with advantageous benefit–cost ratios (E/C > 2.5) are distributed in the middle reaches (S > 3.2 km) and are characterized by low-dam systems (H < 17 m). This framework overcomes the spatial discretization and empirical dependence limitations of traditional check dam siting methods. It achieves prediction errors below 20%, providing a scientific tool that combines mechanistic interpretability and decision-making efficiency for check dam planning. The proposed framework further demonstrates engineering feasibility and transferability to other watersheds, offering practical value for soil and water conservation planning.
How to cite: Deng, M. and Wang, W.: A Multi-Objective Optimization Framework for Check Dam Siting Integrating GIS, a Hydrological–Hydrodynamic Coupling Model, and NSGA-II, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4746, https://doi.org/10.5194/egusphere-egu26-4746, 2026.
Large-scale afforestation is a cornerstone of global ecological restoration, yet its impact on landscape connectivity remains poorly quantified, limiting our understanding of its long-term ecological effectiveness. Traditional assessments rely on structure-based metrics can misrepresent fragmentation trends by overlooking ecological connectivity.
Here, we present a comprehensive analysis of forest dynamics in China's Yellow River Basin, a globally significant restoration region, employing a multi-metric framework that integrates the Connectivity-based Fragmentation Index (CFI) with structure- and aggregation-based indices (SFI, AFI). The results reveal that despite three decades of massive afforestation (1991-2023) driving an 81.6% net forest expansion, this greening has induced a nuanced reorganization of the landscape. Crucially, the perceived trend in fragmentation depended entirely on the metric applied. SFI which sensitive to patch proliferation indicated increased fragmentation for 60% of the forest area, aligning with the widespread establishment of new, often small patches. In stark contrast, CFI which prioritizes functional connectivity revealed a markedly lower proportion (40%) of forest area undergoing increased fragmentation. The finding that CFI indicates less severe fragmentation here than globally observed (>50%) reveals that afforestation has substantially preserved, or even enhanced, functional connectivity amidst growing landscape complexity. Our findings highlight the necessity of integrating connectivity, aggregation, and structural-focused metrics into global fragmentation assessments to accurately evaluate the ecological outcomes of restoration efforts.
How to cite: Gong, M. and Yu, Y.: An integrated connectivity-structure assessment reveals the effects of large-scale afforestation on landscape fragmentation patterns, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12077, https://doi.org/10.5194/egusphere-egu26-12077, 2026.
Plant roots play a critical role in improving soil water retention by regulating soil structure and pore characteristics. Although the effects of monoculture root systems on soil hydrological properties have received considerable attention, natural succession drives vegetation from monoculture to more structurally stable mixed-species patterns, resulting in more complex root systems. However, the mechanisms by which mixed root systems affect soil water retention remain poorly understood. This study examined fibrous and tap root systems of herbaceous plants under three mixing ratios: 1:3 (tap root dominant), 2:2 (equal proportions of fibrous and tap roots), and 3:1 (fibrous root dominant), with bare land as a control. The effects of root systems on soil initial water content (IWC) and saturated water content (SWC) under different mixing patterns were analyzed. The results showed that mixed root systems significantly improved soil water retention, with the 2:2 mixing ratio exhibiting the most pronounced effects. Under this ratio, IWC and SWC increased by 58.4% and 39.6%, respectively, compared to bare land. With increasing root density, IWC and SWC first increased and then decreased, with a critical root length density of 10.4 cm/cm³. Within the mixed system, fibrous roots (IWC: 12.2%; SWC: 16.0%) had stronger effects on soil water retention than tap roots (IWC: 1.5%; SWC: 11.7%). Root systems primarily influence soil water retention indirectly by regulating soil organic matter rather than through direct effects. This study provides theoretical support for understanding infiltration mechanisms of vegetation in the Loess Plateau region.
How to cite: Zhang, S., pan, J., and Ma, J.: Effects of mixed plant root systems on soil water retention in the Loess Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15435, https://doi.org/10.5194/egusphere-egu26-15435, 2026.
Posters virtual: Mon, 4 May, 14:00–18:00 | vPoster spot 2
EGU26-6345 | ECS | Posters virtual | VPS16
High-coverage grass on slope–gully systems effectively mitigates gravity erosion in the Loess PlateauMon, 04 May, 14:06–14:09 (CEST) vPoster spot 2
Abstract: Understanding how vegetation patterns control gravity erosion, such as avalanches, landslides, and mudflows, in slope–gully systems under heavy rainfall, remains a key challenge on the Chinese Loess Plateau. To address this, five 1-h simulated rainfalls were conducted, at an intensity of 1.4 mm/min, on experimental plots. These plots featured a gentle slope of 3° and a gully sidewall of 70°, and were covered with different vegetation patterns. Our results show that high-coverage grass on the gentle slope effectively reduced avalanche magnitude. The plot with 85% grass coverage had the lowest average avalanche volume, at 109.6 cm3, across the five rainfall experiments. Conversely, the excessive restoration of woody vegetation, or planting woody vegetation near the gully shoulder line, markedly increased landslide scale. Across the five rainfalls, the average landslide volume was 1,202.7 cm³ in the plot with 85% tree coverage and 983.3 cm³ in the plot with 60% shrub coverage along the gully shoulder line––both nearly triple that of bare land. Mudflow volumes in most of the plots accounted for less than 10% of the total gravity erosion. Avalanche and landslide volumes were significantly correlated with root mass density, silt content, bulk density, and organic matter, with all correlation coefficients exceeding 0.45. Consequently, implementing high-coverage grass on gentle slopes is one of the most effective strategies for mitigating gravity erosion on gully sidewalls.
Keywords: Gravity erosion; Vegetation pattern; Slope–gully systems; Grass; Loess Plateau
How to cite: Ran, G. and Xu, X.: High-coverage grass on slope–gully systems effectively mitigates gravity erosion in the Loess Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6345, https://doi.org/10.5194/egusphere-egu26-6345, 2026.
