Search Results (722)

Flash floods are among the most damaging hydrometeorological hazards in the Western Balkans (WB), yet regionally consistent, cross-border susceptibility assessments remain scarce because of fragmented national datasets and differing methodological standards. This study develops a harmonized, cloud-based flash-flood susceptibility framework for the WB (208,052 km²) by implementing a physiography-based modified Flash-Flood Potential Index (FFPI) in Google Earth Engine (GEE) at 30 m resolution. The modified FFPI integrates slope, land cover, soil texture, vegetation exposure (Bare-Soil Index), and soil erodibility, and is aggregated across 9524 EU-Hydro sub-basins to produce an operational catchment-level ranking. Additionally, CHIRPS-derived maximum daily precipitation is used to derive a rainfall-triggered hotspot layer that highlights sub-basins where terrain-controlled susceptibility coincides with strong observed rainfall extremes over the 2001–2025 period. Enhanced susceptibility is concentrated in Adriatic and Aegean-facing mountain basins of Albania, Montenegro, and North Macedonia, with 44.2% of sub-basins classified as high or very-high susceptibility. Multi-source validation against inventoried torrential catchments, published GIS-based susceptibility maps, and flood records yielded moderate to very strong agreement (68.6–92.0%), together with an AUC-ROC of 0.79 and F1-score of 0.77 for the pooled orthophoto-based validation dataset (n = 336 sub-basins). The framework provides a reproducible transboundary tool for regional flood-risk screening and demonstrates the potential of cloud-based geospatial platforms to overcome cross-border data fragmentation in hazard assessment. Its main limitations are the static physiographic nature of the FFPI, the coarser resolution of CHIRPS and SoilGrids relative to small sub-basins, and possible overestimation in karst terrains where subsurface drainage reduces surface runoff. Full article

Vegetation distribution is important for regulating overland-flow hydraulics and reducing hydraulic erosion potential on slopes. However, quantitative procedures for determining the maximum admissible spacing of multi-row vegetation under specified soil and design rainfall conditions remain limited. This study combined fixed-bed flume experiments with a theoretical hydraulic model to determine the lateral and downslope vegetation spacings required to maintain the predicted overland-flow velocity below the critical velocity for soil-particle initiation. A total of 120 runoff tests were conducted at a slope gradient of 15° under eight flow discharges (0.3–1.0 L/s) and three vegetation configurations: single-row vegetation with varying lateral spacing b, multi-row vegetation with varying b at d = 0.030 m, and multi-row vegetation with varying downslope spacing d at b = 0.010 m. Flow depth and discharge were measured, and the cross-sectional mean velocity was calculated to evaluate the Reynolds number Re, Froude number Fr, and local resistance coefficient ξ. The measured Re and Fr ranged from 475 to 1770 and from 0.83 to 2.06, respectively, indicating laminar-to-transitional regimes based on Re and predominantly supercritical flow states based on Fr, with limited subcritical and critical cases. Increasing b, d, or Q generally reduced ξ, whereas multi-row vegetation produced greater flow resistance than single-row vegetation. At each Q level, the ξ–b and ξ–d relationships followed power functions with R² ≥ 0.73. An improved local resistance formulation incorporating b, d, Re, and Fr was developed and evaluated using 129 measured data points, yielding R² values of 0.77–0.90. The proposed model was further combined with SCS-CN runoff estimates and a critical initiation velocity criterion for five soil types characterized by mean particle diameter and particle density and five 1-h design rainfall depths of 25–125 mm. Model-derived vegetation-spacing estimates were obtained for 18 of the 25 soil–rainfall scenarios, and denser vegetation distributions were generally required as the design rainfall depth increased. These results provide experimentally informed, model-based guidance for estimating multi-row vegetation spacing under specified soil and rainfall conditions. The proposed relationships and spacing estimates are condition-specific to the fixed-bed experiments with artificial emergent vegetation at a slope gradient of 15° and to the investigated hydraulic and geometric ranges. They should not be interpreted as universal design criteria or direct predictions of field soil erosion; application beyond these conditions requires further calibration and validation. Full article

The spring floods that occurred in 2024 in western and northern Kazakhstan caused extensive damage. Our understanding of runoff formation processes under frozen-soil conditions remains limited. In this study, we apply a coupled hydrothermal model as a case study to explicitly simulate vertical heat and water transport, phase transitions, snow dynamics, and reduced infiltration capacity due to cryogenic pore blockage (ice-filled pores). The model is based on regular meteorological data from 65 stations in five regions covering the full hydrological cycle (August–May) of 2021 and 2024. A multilevel diagnostic check showed that soil temperature is reproduced with a median $R^2$ of 0.962 and NSE of 0.888, the frozen/thawed surface condition corresponds to WMO (World Meteorological Organization) standards on approximately 91% of days, and water balance agreement reaches 86.2% (56 out of 65 stations). The model reflects the regional variability of the 2024 flood. In the northern regions (Kostanay, North Kazakhstan), snowfall was above average, and modeled runoff increased compared to 2021 (for example, at the Sergeevka station, it increased by a factor of four). In the western regions, the trends were mixed: the strongest relative increase in runoff was recorded in the Atyrau region (+119%), whilst in the West Kazakhstan region, the increase was more modest (+19%), and in the Aktobe region, runoff increased by 60%. The key mechanism—the time lag between rapid snowmelt and delayed soil thaw—is clearly evident: peaks in snowmelt occur when the soil remains frozen, infiltration capacity decreases, and the runoff potential index (RPI) exceeds 1 for extended periods. Although the model does not simulate the river channel, its ability to diagnose runoff generation conditions at the slope scale offers a diagnostic framework for identifying runoff-conducive conditions in regions with limited data, rather than a physically validated tool for flood-prone area identification. The results show that the 2024 flood period was characterized by abnormally high water inflow and hydrothermal conditions consistent with a temporal mismatch between water supply and the recovery of soil infiltration capacity. Because the RPI is a diagnostic indicator constructed from water input and infiltration capacity, these results should be interpreted as evidence of conditions conducive to runoff generation rather than as an independent causal verification of the flood mechanism. Full article

The Southern Jiangsu hills region is located within the Yangtze River Delta Ecological Barrier. Soil erosion poses a threat to the development of commercial forests and the water quality of Lake Taihu, making it urgent to quantify the mechanisms by which vegetation and rainfall regulate slope erosion. This study established five standard runoff plots in Zhangzhu, Yixing, and continuously monitored runoff and soil loss from 2022 to 2023. By combining Random Forest modeling, partial least squares structural equation modeling (PLS-SEM), and moderation effect analysis, the study assessed the contributions of various driving factors under different rainfall types. The results indicate that the peach orchard (PEA + GRA) is an optimal ecological model, achieving runoff and sediment reduction rates of over 54.09% and 70.19%, respectively. Rainfall is the dominant factor driving runoff (r = 0.75), while the maximum 30 min rainfall intensity (I₃₀) is the dominant factor driving soil loss (r = 0.82). Furthermore, during low- to moderate-intensity rainfall events, vegetation attributes primarily govern hydrological responses; however, during extreme Type III rainstorms (24 h rainfall exceeding 50 mm), rainfall volume becomes the decisive factor. Moderation analysis further reveals that vegetation height and cover exert significant moderating effects on the initial transition phase from rainfall to runoff. These findings provide evidence-based guidance for optimal soil and water conservation strategy selection in subtropical hilly landscapes. Full article

This study presents a photocatalytic infiltration pavement block designed to combine roadside NO_x removal with rainwater capture and temporary storage. TiO₂ and styrene–butadiene rubber (SBR) latex were incorporated into the pavement block to provide photocatalytic functionality, and direct infiltration holes were introduced to capture surface runoff, enable temporary storage, and promote delayed subgrade drainage. The effects of TiO₂ and SBR latex on compressive strength and NO_x removal were evaluated, while rainwater infiltration performance was examined using acrylic panels with different hole diameters, hole-area ratios, slopes, and V-groove treatments. The use of SBR latex improved the compressive strength of TiO₂-containing mixtures, with T10-L5 showing an 8.1% increase compared with the corresponding non-latex mixture. The same mixture achieved the highest NO_x removal efficiency, reaching 73.0% after 60 min of UV exposure. In the infiltration test, the 5 mm hole configuration gave the most stable runoff reduction, and lattice-type V-grooves improved water capture by connecting adjacent holes and guiding surface flow. A field-scale trial installation confirmed that the integrated infiltration–retention system suppressed visible ponding and runoff, provided delayed subgrade drainage, and maintained pavement stability under vehicle loading. The findings indicate that the proposed block system can provide combined air-purification and stormwater-control functions. Full article

Having reliable tools for characterizing rainfall-induced soil erosion is fundamental to the effective management of agroforestry systems in order to increase resilience against climate change. Physics-based models provide a robust, comprehensive and widely applicable framework to quantify runoff generation and soil erosion during intense rainfall events in agroforestry catchments. In this work, we propose a novel hydro-erosive model to simulate hydrodynamical flow and bed mobilization, movement and deposition. This hydro-erosive model solves the two-dimensional shallow water equations (SWE-2D) with hydrological source terms for runoff generation, coupled with the 2D depth-averaged solid transport and the soil surface evolution equations. The partial differential system is solved using a finite volume method. Alternative Integral/Differential Bed Slope and explicit upwind/implicit pointwise friction term discretization options can be used to improve performance in terms of numerical stability and conservation. The behavior of different discretization options in this hydro-erosive model is evaluated through an analytical hillslope verification, a benchmark V-catchment rainfall–runoff test and a laboratory dam-break experiment over an erodible bed. The results show that the Differential Bed Slope formulation combined with the upwind friction discretization provides the most accurate and conservative predictions. Also, an Upwind Bed Updating method for integrating soil surface elevation change is compared with the cell-centered integration of the bed change term by suppressing non-physical oscillations without compromising computational efficiency. Overall, the proposed open-source hydro-erosive model provides a reliable and computationally efficient framework for high-resolution simulations of rainfall-induced soil erosion and represents a valuable tool for environmental and agroforestry applications, but appropriate calibration and mesh resolution are required to ensure reliable predictions. Full article

The resource utilization of distillers’ grain-derived organic fertilizer is of significant importance for promoting green production of sorghum in Maotai-flavor Baijiu-producing regions and for soil and water conservation on sloping croplands. To determine its appropriate application rate and to clarify its synergistic effects on sorghum growth, soil properties, and soil loss, a runoff-plot experiment was conducted on typical sloping farmland in Renhuai, Guizhou Province. A no-fertilization control (CK) and gradient treatments of distillers’ grain organic fertilizer ranging from 1500 to 10,500 kg ha⁻¹ were established. Responses of sorghum growth, yield components, soil physicochemical properties, aggregate composition, and soil loss were evaluated, and Partial Least Squares Structural Equation Modeling (PLS-SEM) was employed to elucidate the pathways regulating soil erosion. The results demonstrated a pronounced dose–response relationship between distillers’ grain organic fertilizer application and sorghum growth and yield formation. The treatment receiving 6000 kg ha⁻¹ of distillers’ grain organic fertilizer exhibited superior performance in plant height, stem diameter, dry weight per plant, grain dry weight per panicle, and root development. Notably, grain dry weight per panicle and root biomass increased by 307.4% and 130.8%, respectively, compared with CK. Fertilization increased soil organic matter content in the 0–10 cm soil layer and altered the particle size distribution of soil aggregates. Except for the 1500 kg ha⁻¹ treatment, all fertilization treatments reduced total soil loss during the monitoring period. The treatment receiving 9000 kg ha⁻¹ achieved the greatest reduction, decreasing soil loss by 43.8% relative to CK, while the treatment receiving 6000 kg ha⁻¹ reduced soil loss by 38.8%. PLS-SEM results indicated that both root development and yield components were significantly negatively correlated with soil loss. However, the direct effect of fertilization on soil loss was not significant, suggesting that distillers’ grain organic fertilizer primarily reduces erosion risk indirectly by improving soil properties and promoting root development and yield formation. Overall, an application rate of 6000 kg ha⁻¹ of distillers’ grain organic fertilizer for sorghum cultivation on sloping cropland under the conditions of this experiment. Full article

Disentangling the effects of climate variability and forest management on catchment hydrology remains a major challenge in temperate plantation landscapes. We analyzed 21 hydrological years (1997/98–2017/18) of precipitation and runoff records from two experimental catchments in the Chilean Coastal Range with contrasting silvicultural histories to characterize changes in low-flow behavior. Hydroclimatic and low-flow indices were evaluated using the monotonic trends test, Sen’s slope estimates, change point detection, and standardized inter-catchment anomaly differences. Annual and seasonal precipitation indices, rainfall frequency, and maximum dry-spell duration showed no significant monotonic trends, whereas maximum 5-day precipitation declined at LP. The two catchments nevertheless exhibited divergent low-flow trajectories. Los Pinos, managed through partial harvesting and thinning within a forest mosaic, showed decreasing normalized low-flow availability and longer low-flow exposure during the latter part of the record. La Reina, clearcut in 1999/2000 and subsequently reforested, showed a progressive increase in low-flow magnitude and normalized low-flow availability, together with declining flow variability and fewer below-threshold events. Standardized inter-catchment comparisons confirmed a temporal divergence in low-flow behavior. They also revealed a concurrent shift in inter-catchment precipitation anomalies. These results indicate contrasting long-term hydrological trajectories that are consistent with differences in forest management histories; however, the non-paired study design, limited pre-harvest observations at La Reina, and differential precipitation forcing preclude formal attribution to silvicultural effects alone. This study highlights the value of long-term experimental catchments for evaluating low-flow dynamics under interacting climatic and land-management influences. Full article

Soil erosion on sloping farmland impairs cultivated land quality, food security, and watershed ecological sustainability across China. Vegetation serves as a core erosion buffer, yet how nitrogen–phosphorus (N-P) stoichiometry shapes coordinated maize growth to regulate multi-stage runoff–sediment coupling remains underexplored. This study reveals the complete mechanistic chain linking N-P ratios, crop growth synchrony, and hillslope erosion dynamics via 60 mm·h⁻¹ simulated rainfall experiments at three key summer maize stages, with six N/P gradients (0–3.75) in an eastern China brown soil zone. An N/P ratio of 2 optimized maize biomass, canopy cover, and root soil-binding capacity, yielding the lowest sediment concentrations. Excess nitrogen (N/P = 3.75) triggered spindly, mechanically weak maize growth, elevating runoff volume and sustaining high-variability sediment transport. High-frequency runoff–sediment signals maintained a consistent positive correlation, while mid/low-frequency components decoupled under imbalanced N-P supply. Moderate balanced N-P fertilization (N/P = 1–2) stabilized hillslope hydrological-erosion processes throughout the growing cycle, whereas surplus nitrogen induced asynchronous erosion responses. This research delivers quantitative evidence for coordinated high-yield and erosion-control nutrient management. Full article

Vegetation restoration is widely used to combat soil erosion on the Chinese Loess Plateau, where intense rainfall and steep slopes make this region one of the most eroded areas in the world. However, the effectiveness of strip grass cover (Vc) in reducing erosion under varying rainfall and topographic conditions remains insufficiently quantified. In this research, based on indoor simulated rainfall experiments in a soil tank, we investigated the erosion characteristics of slopes under six Vc levels (0%, 20%, 30%, 40%, 50%, and 60%), three rainfall intensities (RI) (1.33, 1.67, and 2.0 mm·min⁻¹), and four slope gradients (SG) (10°, 15°, 20°, and 25°), and quantified the effects of Vc on slope erosion processes. Runoff and sediment reduction effects by Vc ranged from 3.5% to 62.6% and from 15.2% to 99.1%, respectively. An exponential decay in erosion rate was observed with increasing Vc, whereas runoff velocity initially decreased and then increased as the Vc increased. By integrating RI, SG, and Vc, the average runoff rate and erosion rate models accurately simulate erosion processes on Vc slopes. These findings provide laboratory-based evidence that Vc substantially reduces slope erosion, and support the development of empirical models for predicting runoff and erosion under the tested conditions. Full article

Urban hillside areas concentrate hydrological and geotechnical risks intensified by accelerated urbanization and climate change. Although Nature-Based Solutions (NbS) are increasingly recognized as promising strategies for urban resilience, their application in hillside environments remains limited in scientific literature. This study integrates bibliometric analysis and a Systematic Literature Review (SLR) based on searches conducted across Scopus, ScienceDirect, and Web of Science from 2020 to 2025. Of the 4435 retrieved publications, only 92 addressed the association between NbS, hydrological modeling, and urban hillside environments. This reduction suggests that research integrating these themes remains limited within the adopted search criteria. The results demonstrate that hillside occupation in the Global South is conditioned by socio-spatial inequality, increasing exposure to landslides, erosion, and hydrological hazards. NbS were shown to reduce runoff peaks and contribute to slope stabilization when strategically positioned and adapted to slope gradient and hydrological connectivity; however, their effectiveness depends on continuous maintenance and monitoring. Comparative assessment indicates that most hydrological models are still applied in isolation, limiting the representation of coupled infiltration, soil saturation, and subsurface instability processes. The results indicate that effective NbS implementation in urban hillside areas requires integrated modeling approaches, interdisciplinary frameworks, and risk-oriented urban planning, particularly in socio-environmentally vulnerable contexts. Full article

The middle–lower Huaihe River Basin faces persistent flood and waterlogging threats, with river–lake interactions being a critical yet underexplored factor constraining flood discharge capacity. This study investigates the flood discharge capacity and erosion–deposition dynamics in the Bengbu–Hongze Lake reach and proposes sustainable management solutions. By analyzing long-term hydrological data (1954–2020) and cross-sectional measurements (1971–2025), we quantified changes in channel morphology and flood behavior. The results reveal that while upstream inflow has remained stable (annual runoff 20.5–33.3 billion m³), sediment concentration has continuously declined by approximately 80%—from 0.474 kg/m³ in the 1950s to 0.094 kg/m³ in the 2020s. The main channel exhibits persistent incision totaling 135.7 × 10⁶ m³, while floodplains have undergone progressive aggradation of 35.1 × 10⁶ m³, reflecting a sediment-starved river system in geomorphic disequilibrium. Critically, the riverbed leading to Hongze Lake exhibits an adverse slope, rising from –10 m at Fushan to over +9 m at Laozishan, while the lake’s sedimentation has reduced its storage capacity by 29% since the 1980s (from 31.27 × 10⁸ m³ to 22.15 × 10⁸ m³). Despite extensive engineering interventions, significant issues persist—including the backwater effect of Hongze Lake, prolonged high water levels during moderate floods (in 2020, water level at Fushan reached 18.34 m at only 61% of the design discharge), and exacerbated waterlogging in riparian lowlands. Therefore, we advocate for a paradigm shift towards a river–lake separation scheme, specifically, an inner-lake embankment approach. This nature-based solution aims to restore the river’s physical structure and harness its self-shaping morphological function for long-term flood management and ecological sustainability. Our findings provide a quantitative basis for re-evaluating the river–lake relationship and offer a strategic direction for sustainable flood management in highly altered alluvial river systems. Full article

Substantial declines in acidifying emissions across Europe have led to pronounced chemical recovery of Norwegian surface waters. In recent decades, however, changes in water chemistry have increasingly coincided with climate change, complicating the attribution of observed trends to individual drivers. This study assesses whether ongoing climate change has produced detectable effects on freshwater chemistry in Norway and how these effects vary among catchments with differing sensitivities to acidification. In this study, the Model of Acidification of Groundwater In Catchments (MAGIC), which is based on current understanding of the processes governing acid–base chemistry in soils and waters, was used to simulate the effects of declining acid deposition. Deviations between observed and modelled water chemistry were provisionally interpreted as climate-related effects. However, these residuals may also reflect model or parameter uncertainty and other unaccounted-for processes. The analysis draws on long-term monitoring data (1986–2022) from 59 acid-sensitive Trend Lakes distributed across Norway, together with four Field Research Stations (1986–2020) representing contrasting hydroclimatic and biogeochemical conditions. Temporal trends were evaluated using the Mann–Kendall test and Sen’s slope estimator, while relationships between inferred climate effects and climatic variables were examined using Pearson’s correlation analysis. Across the Trend Lakes, inferred climate effects were predominantly positive for acid-neutralising capacity (ANC) and weathering-derived cations, suggesting that climate change may contribute to accelerated chemical recovery, particularly in catchments less sensitive to acidification. The inferred climate effects varied substantially among the Field Research Stations. Higher temperatures were generally associated with enhanced recovery, possibly through intensified silicate weathering, whereas increased precipitation and runoff appeared to dampen recovery. Overall, the results suggest that climate change exerts a measurable influence on freshwater chemistry in Norway, although the magnitude and direction of the response are strongly modulated by catchment-specific characteristics. While previous studies have identified climate-related influences on individual chemical variables, quantitative attempts to separate climate- and acid-deposition-related effects across a large number of acid-sensitive catchments remain rare. Here, we use deviations between observed water chemistry and MAGIC simulations of acid deposition recovery as a screening approach to investigate whether climate-related signals can be detected at the national scale and whether these signals vary among catchments with differing sensitivities to acidification. Full article

Nitrogen export dynamics in small watersheds of subtropical dry–hot valleys remain poorly characterized. This study investigated runoff nitrogen patterns in a typical mango planting area lacking long-term monitoring by coupling in situ monitoring with the SCS-CN model to optimize parameters and the river-entry coefficient during the research period of 2021–2022. Results showed that runoff nitrogen concentration peaked significantly from May to August (p < 0.05), with NO₃-N as the dominant form, accounting for 51.50~76.56% of total nitrogen. The SCS-CN parameter λ exhibited a highly significant linear correlation with monthly rainfall (p < 0.01), ranging from 0.07 to 0.30. Spatially corrected TN river-entry coefficient (0–0.50) were elevated in riparian zones with steeper slopes. Annual TN loads were 5.902 kg/ha and 5.566 kg/ha, respectively. Overall, May to August constitutes the critical period for nitrogen export in this dry–hot valley, primarily as NO₃-N. Optimizing model parameters enhances the applicability of the SCS-CN model, revealing that nitrogen influx into rivers is concentrated near steep riverbanks, providing a scientific basis for pollution control in sloping orchards. Full article

Against the background of global warming, snow cover, as an extremely sensitive and active component of the cryosphere, plays an indispensable role in regulating regional water circulation, energy balance mechanisms and the climate system. To explore the dynamic variation characteristics and driving mechanisms of snow depth in southeastern Xizang, this study took Chamdo City as the research area. Based on multi-source datasets including snow depth, meteorology, vegetation, topography, and population density from 2000 to 2020, methods such as the coefficient of variation, Theil–Sen trend analysis, Mann–Kendall test, Hurst index, and geographical detector were adopted to systematically analyze the spatiotemporal patterns of snow depth variations and their influencing factors. The results indicate that, temporally, the overall snow depth in Chamdo City showed a fluctuating increasing trend over the past 20 years, with an annual growth rate of 0.03 cm. It exhibited distinct characteristics across three stages: snow depth increased at a rate of 0.12 cm·a⁻¹ from 2000 to 2005, decreased at 0.05 cm·a⁻¹ during 2005–2015, and rose rapidly from 2015 to 2020 at a growth rate of 0.52 cm·a⁻¹. Spatially, the distribution of snow depth varied significantly. The extremely shallow snow cover area (≤2 cm) accounted for 51.71% of the total area, primarily concentrated in low-altitude regions with intensive human activities. In contrast, the relatively deep (6–10 cm) and extremely deep (>10 cm) snow cover areas together constituted 14.34% of the total, mainly distributed in high-altitude regions with sparse populations. Hurst index analysis revealed that 61.71% of the study area exhibited persistent changes in snow depth, with a trend toward deepening snow cover in the future. The results from the geographical detector show that air temperature (X9, q = 0.90) was the core driving factor dominating the static spatial differentiation of multi-year average snow depth. Furthermore, the interactions between slope (X4) and air temperature (X9), vegetation type (X6) and air temperature (X9), and population density (X5) and aspect (X8) all demonstrated bivariate enhancement effects, with explanatory power significantly higher than that of individual factors. This study provides a scientific reference for water resource management, snowmelt runoff prediction and snow disaster prevention in Chamdo City. Full article