Most sediments in the Loess Plateau of Yellow River basin originate from the gullied-hilly loess terrain, with approximately 50% deriving from gully systems which is the dominant geomorphological features. Accurately simulating the water and sediment processes in this area remains challenging due to the intricate sediment generation mechanisms within the slope-gully-river cascading systems. This study presents an enhanced version of the physically-based distributed hydrological model WEP-SED to reflect the influence of topographic slope variations on sediment production and transport processes.The WEP-SED employs a three-tiered hierarchical structure (slope-gully-river continuum) to simulate coupled water-sediment dynamics (Fig. 1), which includes splash erosion, runoff & overland flow erosion, conflux & erosion in slope-gully, gravity erosion, conflux & sediment transport, and conflux & sediment transport.In the new model, the contour band in the sub-watershed is changed to upper-middle-down slope band, which is designed to better resolve slope-dependent erosion dynamics. This spatial discretization methodology accounts for both hydrological flow paths and local slope gradients, enabling more precise representation of erosion processes across varying topographic conditions, especially the mechanism of seriously soil erosion in the steep slope terrain and sedimentation in the valley floor of the gully. The refined sediment transport mechanisms within each slope band are schematically depicted in Figure 2. The breakpoint for the three slope band is 10°, one is the first one from top to bottom, the other is the first one from bottom to top, where the slope is just change over 10°. In the upper gentle slope band, the splash erosion and runoff & overland flow erosion is considered; in the middle steep slope band, splash erosion, runoff & overland flow erosion, conflux & erosion in slope-gully, gravity erosion is considered; in the down gentle slope band, splash erosion, runoff & overland flow erosion, gravity erosion, conflux & sediment transport in gully and river is considered.The enhanced model was implemented in the Nanxiaohe sub-watersheds to investigate erosion-sediment dynamics during seven flood events in August 2009. It indicates that the model performs a relatively good fitness in simulating the water and sediment processes, and reflects the erosion difference in seven flood events. According to the model simulation results, the middle steep slope band constituted the dominant sediment source (70%), followed sequentially by down gentle slope band (27%) and the Upper gentle slope band has the smallest contribution. Thus, the enhance model could reflect the slope impact on sediment erosion and transport in Loess Plateau, which could be used for the benefit evaluation of soil and water conservation engineering projects.Fig 1. A schematic illustration of the model structs and principle of the WEP-SED model.Fig.2 Schematic diagram of geomorphic unit division

It remains a major challenge to determine the suitable spatial extent of vegetation restoration within a watershed to balance upstream water conservation (WC) and downstream water supply. To address this trade-off, we propose a novel framework that integrates scenario analysis with multi-objective decision-making methods. The framework primarily consists of three key steps. Firstly, the Water and Energy process in Large River Basin (WEP-L) model is employed to identify the most suitable Land Use/Land Cover (LULC) conversion type to enhance the main WC functions in each sub-basin. Secondly, a multi-objective decision-making approach was developed to simultaneously maximize upstream WC and downstream water supply, incorporating a food security constraint for the study area. Finally, the ideal point method was applied to determine the optimal extent of vegetation restoration that best balances these competing objectives. The framework is implemented in the water conservation area of the Wei River Basin (WCA-WRB), a critical region in the Wei River Basin of China. The results indicated that converting 28% of the study area to the LULC type most suitable for the function of decreasing floods would be the most effective strategy. This corresponds to a vegetation restoration area of approximately 3757 km2, of which approximately 3092 km2 of cropland was converted to vegetation, representing 5% of the total study area. This proposed framework offers a valuable reference for guiding vegetation restoration projects in similar semi-arid and semi-humid regions.

The solution for large-scale multi-objective optimization operation modelling of cascade reservoirs is always one of the difficult issues and hot topics for water resources operation and allocation. However, the multi-objective operation model has the characteristics of complex hydraulic connection, high-dimensionality, and multiconstraint, and how to efficiently and accurately solve and model is always a challenge in decision-making and management of water resources. To avoid the phenomenon and limitations of the conventional studies on the solution of the operation model used to excessively depend on intelligent optimal algorithm without taking the complex hydraulic connections of variables into consideration, in this paper, a new approach of a synergistic optimization strategy combining a decomposition optimization framework (DOF) with an improved Nondominated Sorting Genetic Algorithm II (NSGA-II) was proposed. The new method completely avoided the curse of dimensionality by variable division, boundary condition transmission, and hydraulic connection reconstruction, and significantly improved the computational efficiency and accuracy of the global optimization (GO). The Lancang River (LCR) cascade reservoirs were selected as a case study, and the multi-objective model was constructed to apply the new approach. The results show that compared with the GO, the GO by the DOF (GO-DOF) reduces the computational time by 86.9 %, significantly decreases the degree of ecological change (DEC) by 42.6 % with power generation decreasing by only 0.6 %. It is concluded that the DOF shows excellent performance in both computational efficiency and operation outcomes, providing a new approach to an efficient solution for the operation and allocation optimization of complex water resources systems.

Study regionthe Second Songhua River Basin in Northeast ChinaStudy FocusThis study integrates CMIP6 multi-model climate projections, the WEP-QTP distributed hydrological model, and XGBoost-SHAP analysis to simulate future climate, freeze–thaw processes, and water resource responses under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. The study evaluates the impacts of temperature and precipitation changes on freezing depth, runoff, infiltration, groundwater recharge, and water resources, while quantifying the contributions of climatic drivers to freeze–thaw evolution and hydrological responses.New Hydrological Insights for the RegionThe results show that continued warming increases shallow soil temperature and significantly alters freeze–thaw regimes, with the most pronounced changes occurring under SSP5-8.5. A 1 °C increase in shallow soil temperature reduces freezing depth by 0.055 m, while air temperature explains 90.3% of the variation in freezing depth. Precipitation is the dominant factor controlling hydrological changes, particularly infiltration, explaining 73.5% of its variation. Future scenarios indicate decreases in surface runoff and streamflow but increases in infiltration and groundwater recharge. During 2081–2100, surface runoff decreases by 11%–30%, whereas infiltration and groundwater recharge increase by 12%–22% and 9%–16%, respectively. Under SSP5-8.5, total water resources increase by 8%, with surface water and groundwater resources increasing by 0.3% and 15.3%, respectively. These findings enhance understanding of freeze–thaw impacts on hydrological processes and support water resource sustainability under climate change.

Study regions The water conservation area in the Yellow River Basin (YRB WCA) of China, a key ecological function zone with high annual runoff coefficients. Study focus Most water conservation (WC) function assessments in large basins focus on quantity. This study proposes a new framework for evaluating both the quantity and three main functions. A distributed hydrological model calibrated with multi-variable data was used to improve accuracy. New hydrological insights for the regions WC quantity significantly decreased only in Region II (Southern Wei River tributaries). Across all regions, vegetation ecological water use (WC-f1) generally improved, flood reduction (WC-f2) remained stable, while baseflow enhancement (WC-f3) weakened only in Region II. Precipitation and NDVI were primary driving factors of WC quantity, with positive effects except in central Region I (above the Lanzhou area). Temperature, evapotranspiration, and DEM also influenced the three functions. In addition, changes in forest, cropland, and built-up areas since 2000 had strong localized influences on WC-f1 and WC-f2, though their overall impacts were weak. Vegetation restoration strategies should vary by downstream water demand and functional priorities: reduce vegetation cover in central Region I to enhance WC quantity; increase vegetation cover in southeastern Region I and Region III (the Yiluo River Basin) to enhance WC-f2; reduce grassland area in northern Region I and western Region II to enhance WC-f3.

Hydrological models, as critical tools for water resource management, flood prediction, and ecosystem simulation, rely heavily on efficient sharing and collaboration to advance scientific research and engineering applications. Traditional hydrological models, often developed in standalone environments, face challenges such as data silos, cumbersome collaboration workflows, and coarse-grained permission management. While cloud computing has enabled the migration of hydrological models to cloud platforms, two core challenges persist in multi-user collaboration: (1) the complex hierarchical dependencies of model and data resources, which require data integrity during sharing, and (2) the need for fine-grained permission design to balance openness and security. This paper addresses these issues by proposing a cloud-based collaborative sharing method for hydrological models that integrates multi-user, multi-level, and multi-permission mechanisms. By establishing a dual-role system (individual users and administrators), categorizing data resources into five hierarchical levels (modeling data, input data, parameter schemes, scenario schemes, and simulation results), and defining three permission mechanisms (usage, co-construction, and backup rights), the method achieves efficient sharing and secure control of models. The framework supports dynamic model sharing, bookmarking, and backup while ensuring data dependency integrity. Empirical validation demonstrates significant improvements: collaborative task completion time is reduced. This method provides technical support for cloud-based transformation of hydrological models and offers new insights for cross-domain model sharing and collaborative innovation.

The numerous uncertainties in the process of water resource development and utilization bring multiple risks to water resource management. To enhance socio-economic benefits while considering ecological benefits, it is urgent to deeply explore risks. In this paper, Nuozhadu, Jinghong, and Ganlanba hydropower stations on the lower reaches of the Lancang River are taken as the objects. To balance the socio-economic and ecological benefits, a multi-objective optimization operation model was constructed. To describe the risk transmission, a VAR model was constructed, and the dynamic transmission among risks was explored. The results show that the ratio of ecological change is 10.38%, and the cascade power generation is 33,243 GWh (2% higher than the designed). The impacts of the perturbation for each risk on itself and others are quantitatively analyzed by the impulse response function. It is concluded that the transmission direction is generally positive, but the increase in ecological risk has negative impacts on risks of output and abandoned water, and risks of power generation and output also negatively affect abandoned water risk. Finally, the risk transmission is quantitatively estimated by the variance decomposition method. It is concluded that the power generation risk contributes most to the output and ecology risks, the ecological risk only contributes significantly to the abandoned water risk (the contribution rate is 6.30%), and the abandoned water risk contributes a lot to the others.

With water resource shortages becoming a global concern, water conservation (WC) is a key factor for the sustainable development of watershed ecosystems. WC in the headwater region is sensitive to both climate and land use changes, and once damaged, it is difficult to restore. However, few studies have analyzed the spatiotemporal variations of WC in the Ganjiang River headwater region (GJHR). Therefore, this study applies the Water and energy transfer processes in large river basin (WEP-L) model and the water balance equation to assess the spatiotemporal variations of WC in the GJHR during 1957–2018. Results show that: (1) the annual mean WC was 552.3 mm during 1957–2018, and with an increasing trend of 0.85 mm/a. (2) WC ranged from 44.2 to 1178.6 mm, with higher values in the north and south, while lower values in the west. The highly and extremely important area are mainly in the north central and southern parts of the GJHR, they provide water resources security for the GJHR, which needs to be protected on a priority basis. (3) From 1980 to 2014, the dominant land use change was the conversion of forest to farmland, leading to a reduction in forest and an increase in farmland. (4) The decrease in forest and increase in farmland reduced WC. Precipitation was the main factor influencing the spatiotemporal variations of WC. There is obvious spatial heterogeneity in the WC in the GJHR. Future ecological restoration planning should prioritise a scientifically optimised spatial layout that enhance WC capacity and mitigating regional disparities. These findings provide a scientific basis for water resources management and ecological restoration in the source region.

Many regions worldwide are grappling with climate change impacts, including rising temperatures and increasing crop evapotranspiration (ETC) or irrigation water requirement (IWR); however, “paradoxes” of decreasing ETC or IWR despite warming conditions exist. Quantitative research on how climate change induces IWR fluctuations remains limited. This study aimed to propose a new framework to quantitatively assess the effects of climate change factors on IWR. Using the Penman-Monteith method, we calculated daily reference evapotranspiration and used the single-crop coefficient method to compute ETC. We developed a field water balance model to determine the IWR and quantified climatic factors affecting IWR changes through multifactor attribution analysis. Focusing on Jiangxi Province in China’s middle and lower reaches of the Yangtze River Basin, we conducted a comprehensive analysis between 1956 and 2021, examining the IWR of early, middle, and late rice crops. Despite the rise in global temperatures attributed to climate change, an overall decline was observed in rice IWR. This decline was significant for middle rice, not early or late rice. A significant decrease in sunshine duration, wind speed, and rising precipitation primarily drove the IWR reduction, contributing to 32.7, 18.7, and 59.4

The Tabu River Basin (TRB) is one of the most ecologically fragile areas in the arid regions of northern China; it is a key component of the desert steppe north of the Yinshan Mountains. The fractional vegetation coverage (FVC) represents a vital indicator of ecological health in the TRB. In this study, we explored the impacts of climate change and human activities on vegetation growth and utilized Landsat data (30 m) from the Google Earth Engine to generate a long-term FVC dataset (1986–2023) in the TRB. Furthermore, we established a framework for quantitatively identifying the effects of climate change and anthropogenic activities on the FVC in desert steppe regions. The results revealed that: (1) the FVC exhibits considerable spatial heterogeneity, with higher values observed in the southeastern and southwestern areas and lower values in the northern part; (2) over the past 38 years, the annual average FVC has shown fluctuations, with a slight declining trend, while the Hurst exponent indicates a reverse persistence pattern in the FVC across the TRB; and (3) the correlation between the FVC and the temperature is marginally stronger than that with precipitation, and the influence of climate change on promoting the FVC outweighs the role of human activities. These results offer valuable insights for ecological restoration and sustainable development efforts and provide scientific support for monitoring vegetation in the region.

The proportion of non-perennial rivers within the global river network is increasing, and research on these rivers has significantly grown in recent years due to their important role in water resource management and ecosystems. However, existing identification methods primarily rely on river networks with monitoring data and often overlook the temporal variation in flow, limiting further research and analysis. We propose a novel identification approach that couples the WEP-L model with random forest prediction, based on a comprehensive analysis of the limitations of current methods. Specifically, this method involves simulating river flow and incorporating time-series forecasting to facilitate the identification of non-perennial rivers. This approach also divides non-perennial rivers into significantly seasonal and non-significantly seasonal rivers by incorporating seasonal analysis, providing a theoretical foundation for studying their causes and formulating conservation strategies. Using the Yellow River basin in Gansu province as a case study, the results indicate that the total length of non-perennial rivers is 13,085.67 km, accounting for 42.09% of the region’s river length. The cessation periods of significant seasonal non-perennial rivers are primarily in fall and winter, while flow periods are concentrated in summer. The findings provide valuable guidance for the ecological conservation and sustainable management of non-perennial rivers, both in the Yellow River basin and other regions. The introduction and application of this method are expected to improve the identification and management of non-perennial rivers, contributing to the long-term sustainability of water resources.

Cold regions are particularly vulnerable to climate change. Thus, evaluating the response of water quality evolution to climate change in cold regions is vital for formulating adaptive countermeasures for pollution control under changing climatic conditions. Taking the Songhua River Basin (SRB) in Northeast China as the target area, we designed a water–heat–nitrogen coupled model based on the principle of water and energy transfer and nitrogen cycle processes model (WEP-N) in cold regions. The impact of climate change on pollution load and water quality was analyzed during the freezing, thawing, and non-freeze–thaw periods by taking the sudden change point (1998) of precipitation and runoff evolution in the SRB as the cut-off. The ammonia nitrogen load at Jiamusi station, the outlet control station in the SRB, was decreased by 1502.9 t in the change period (1999–2018) over the base period (1956–1998), with a − 9.2

On August 8th, 2022, an extreme rainfall event (the 88ER) occurred over South Korea's metropolitan area and resulted in immense losses of human lives and properties. Previous study has attributed the rainfall event to the intersection of warm and cold air induced by a Northeast China Cold Vortex (NCCV) and the persistently northward displacement of the West Pacific Subtropical High (WPSH). However, in addition to dynamic drivers, understanding the moisture transport of the 88ER is likewise crucial for developing effective strategies to prevent rainstorm disasters. In this study, based on the output from a WRF model, the primary moisture sources and transport pathways of the 88ER are investigated in a Lagrangian view. The Yellow Sea and East China Sea (YSECS) are identified as the most significant moisture source region (84.42%), followed by South Korea (KR), the eastern China (EC) and Democratic People's Republic of Korea (DPRK), which contribute 12.52%, 1.52% and 1.43% of the released moisture, respectively. Furthermore, to assess the sensitivity of moisture fluxes and heavy rainfall to the sea surface temperature (SST) anomalies in the YSECS, an additional WRF model experiment is conducted in which the SST anomalies are replaced by the average SST over the past 30 years. It is found that the SST anomalies in the YSECS cause differences in atmospheric circulation, and therefore exert a strong influence on moisture transport. The SST anomalies finally enhance the moisture contribution of the YSECS by 1.72%, but decrease that over KR, EC and DPRK by 1.03%, 0.35% and 0.33%, respectively. This study aims to explore the primary moisture sources of an extreme rainfall event that occurred over South Korea in August 2022 from a Lagrangian perspective. Meanwhile, the sensitivity of moisture transport to the warm sea surface temperature in the the Yellow Sea and East China Sea are investigated. image

In order to increase the capability to understand and quantify the spatial differences in terrestrial water storage (TWS), and to reflect the unique energy balance processes and soil freeze-thaw mechanisms in the Qinghai-Tibet Plateau (QTP), this study improved the energy balance processes of the water and energy transfer processes model, including its surface radiation calculations and snowmelt module. By integrating these improvements, a water and energy transfer processes model in Qinghai-Tibet Plateau (WEP-QTP) for the Yellow River source region (YRSR) is developed. Using the improved WEP-QTP model to perform simulations, we assessed the daily changes in snow cover, soil moisture (SM), permafrost (PM), and groundwater storage (GWS) in the YRSR. Our analysis revealed an increase in TWS of 0.24 mm/yr from 1961 to 2020. Snow water equivalent (SWE), SM, PM, and GWS have proportional contributions of 8.33%, 216.67%, -154.17%, and 29.17% to the increased TWS, respectively. SM is the primary component of TWS. Temperature (T), precipitation (P), evapotranspiration (E), and solar radiation (Rs) influence the spatiotemporal variations in TWS, as well as those of its components. The increase in P is the primary cause for the rise in TWS, SWE, and SM, while the increase in T predominantly contributes to the decrease in PM. Furthermore, permafrost degradation and climate-induced warming and humidification lead to increased infiltration, resulting in elevated GWS.

Climate change and anthropogenic activity are the primary drivers of water cycle changes. Hydrological droughts are caused by a shortage of surface and/or groundwater resources caused by climate change and/or anthropogenic activity. Existing hydrological models have primarily focused on simulating natural water cycle processes, while limited research has investigated the influence of anthropogenic activities on water cycle processes. This study proposes a novel framework that integrates a distributed hydrological model and an attribution analysis method to assess the impacts of climate change and anthropogenic activities on hydrological drought The distributed dualistic water cycle model was applied to the Fuhe River Basin (FRB), and it generated a Nash-Sutcliffe efficiency coefficient > 0.85 with a relative error of <5 %. Excluding the year with extreme drought conditions, our analysis revealed that climate change negatively impacted the average drought duration (-105.5 %) and intensity (-23.6 %) because of increasing precipitation. However, anthropogenic activities continued to contribute positively to the drought, accounting for 5.5 % and 123.6 % of the average drought duration and intensity, respectively, because of increased water consumption. When accounting for extreme drought years, our results suggested that climate change has contributed negatively to the average duration of drought (-113.2 %) but positively to its intensity (7.8 %). Further, we found that anthropogenic activities contributed positively to both the average drought duration and intensity (13.2 % and 92.2 %, respectively). While climate change can potentially mitigate hydrological drought in the FRB by boosting precipitation levels, its overall effect may exacerbate drought through the amplification of extreme climate events resulting from global climate change. Therefore, greater attention should be paid to the effects of extreme drought.

[目的]水资源是黄河流域经济社会发展的刚性约束,科学评估水源涵养区的水源涵养量,对流域生态环境保护与高质量发展具有重要意义.[方法]针对当前水源涵养量评价存在的不足,从流域水循环角度出发,辨识了多要素对水源涵养功能的影响机制,提出了契合黄河流域特点的水源涵养量评价目标、原则与方法.在此基础上,构建了以分布式水文模型为核心的评价工具,对黄河水源涵养区的水源涵养量进行了评价.[结果]主要研究结论如下:(1)植被的水源涵养功能体现在汛期调蓄洪水、坦化洪水过程,在枯水期增加基流和水资源供给量;土壤的蓄水能力/调节库容即其水源涵养能力,与土壤层厚度、有效蓄水量成正比,并且在一定时期内存在多个"蓄满—释放—再蓄满"过程;含水层的调蓄能力即其水源涵养能力,与含水层厚度、储水/释水能力成正比;不同资源开发利用方式对水循环过程施加影响,进而将这种影响传递到水源上.(2)黄河水源涵养区水源评价,应以提升全流域水安全综合保障能力为目标,统筹全流域生态安全、防洪安全以及供水与能源安全需求;应同时考虑平水时段的"滞留"、汛期时段的"调峰"、枯水时段的"产水"三项功能.(3)黄河水源涵养区1960-2018年多年平均年度水源涵养量为205.04亿m3,其中汛期时段涵养量153.27亿m3、平水时段涵养量38.64亿m3、枯水时段涵养量13.13亿m3;从空间分布看,兰州以上片区、渭河南山支流片区和伊洛河片区水源涵养量分别占全区的55.7％、34.1％和10.2％.[结论]研究成果可谓黄河水源涵养区水源涵养量评价提供参考.