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

The Ten Tributaries Basin is one of the most severely eroded regions in the Yellow River Basin, and its dynamic soil erosion processes are critical to regional ecological conservation. Based on remote sensing data from 1990 to 2023, this study integrated the Revised Universal Soil Loss Equation (RUSLE), the Optimal Parameter-based Geographical Detector (OPGD), and Partial Least Squares Structural Equation Modeling (PLS-SEM) to systematically analyze the spatiotemporal evolution of soil erosion and its multi-factor driving mechanisms. The results indicate that: (1) The basin-wide average soil erosion modulus decreased by 76.29

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.

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.

Amid accelerating climate change, extreme drought events occur frequently, and the conflict between water supply and demand has intensified, exerting severe impacts on domestic water use, productive activities and ecosystem integrity. This paper develops a policy framework for the adaptive management of river ecological flow, specifically designed to align with the unique characteristics of each basin. From the perspective of 'whole-basin governance' and 'adaptive management', we construct a feedback mechanism encompassing 'Problem Diagnosis-Resource Allocation-Regulation Management-Effect Evaluation-Feedback Adjustment'. Through continuous monitoring of drought, the D-A-R (Determination, Assessment and Reduction) approach is employed to dynamically regulate various water use allocations. Empirical research conducted in the Poyang Lake Basin (PY) and the Dongjiang Headwater Watershed (DJ) indicates that by considering hydrological rhythms, water resources carrying capacity, and water resource demands specific to basins, different intervention measures and adjustment scales can be implemented, thereby minimizing the impacts of water resource scarcity. Specifically, introducing the 'hedging rule' cuts the basin's severe-shortage frequency by more than 70%, safeguards ecological flows, and sustains secure water supplies for both households and productive sectors. This paper offers innovative insights and methodological guidance for formulating adaptive policies that simultaneously safeguard riverine ecosystems and foster sustainable socio-economic development within river basins.

Abstract Effective sediment management in reservoir–river coupled systems remains a global challenge due to the conflicting objectives of sediment evacuation from reservoirs and deposition reduction in downstream reaches. This study proposed a physics‐based modeling framework oriented to a reservoir–river coupled system, which integrates morphodynamic calculation and reservoir operation simulation via a two‐way feedback mechanism. Unlike simplified approaches, this framework captures complex transient flow‐sediment processes at the system scale. The study region covers the 1,000‐km Tongguan–Lijin reach in the Middle and Lower Yellow River, encompassing the Sanmenxia–Xiaolangdi cascade reservoirs. This region represents a typical reservoir–river coupled system facing an urgent need to balance the conflicting objectives. The validation results demonstrated that the proposed model achieved high‐fidelity modeling of flow‐sediment fluxes in reservoirs and downstream reaches. Multi‐scenario simulations and sensitivity analyses provide quantitative insights into how the overall sediment transport efficiency responds to varying reservoir operation parameters during the period of Water‐Sediment Regulation Scheme, including replenishing discharge and regulation water volume. In addition, this study identifies distinct optimal operation strategies for different deposition reduction targets: a sharp and short‐duration flushing mode can maximize the reservoir sediment evacuation, while a low‐discharge but long‐lasting release process can maximize the downstream channel erosion. Further simulations across various flow‐sediment regimes demonstrate the universality of the proposed operation strategies. The findings provide insights for adaptive selection of reservoir operation strategies when addressing the conflicts between different stakeholders at a flood‐event scale.

The Haidian District was, historically, rich in water resources. However, with urban development, the groundwater levels have declined, and most rivers have lost their ecological baseflows. To restore the aquatic ecosystems, the district has implemented a cyclic water network and advanced water replenishment projects. Nonetheless, the existing replenishment strategies face challenges, such as an insufficient scientific basis, lack of data, and high energy consumption. There is an urgent need to develop a scientifically robust ecological water replenishment system and optimize pump station scheduling to enhance water resource management efficiency. This study addresses the ecological water replenishment needs of seasonal rivers by integrating the Literature method, Rainfall-Runoff method, and R2cross method to develop a comprehensive approach for calculating the ecological flow and water depth. The proposed method simultaneously meets the ecological functionality and landscape requirements of seasonal rivers. Additionally, the SWMM model is employed to design intelligent pump station scheduling rules, optimizing the replenishment efficiency and energy consumption. Through field measurements and data collection, the ecological water demands of the river channels in different areas are assessed. Using a hydrodynamic model, the dynamic variations in the ecological flow and water depth are simulated. For the Cuihu, Daoxianghu, and Yongfeng areas, this study reveals that the current replenishment volume is insufficient to meet the landscape and ecological needs of the rivers. Most rivers require a 20–30% increase in water levels, with the Dazhai qu needing a substantial rise from 0.17 m to 0.3 m, representing an increase of 76%. Additionally, the results demonstrate that intelligent pump station scheduling can significantly reduce operating costs and energy consumption by dynamically adjusting the replenishment timing and flow rates. This approach optimizes the intervals between equipment activation and deactivation, thereby balancing ecological and energy-saving goals. This research not only provides technical support for the precise calculation of ecological replenishment volumes and the intelligent management of pump stations, but also offers scientific references for water resource management in similar regions. The findings will enhance the ecological functions and landscape quality of the rivers in the Haidian District while promoting refined and intelligent regional water resource management. Moreover, this study presents innovative solutions and theoretical foundations for water resource regulation under the backdrop of climate change.

【Objective】Evapotranspiration is a critical component of hydrological cycling and accurately estimating it is essential to improving water resource management in catchments. In this paper, we proposes a new model to stimulate the evapotranspiration of barley in the Tibetan Plateau.【Method】A physically-based model that integrates hydrological process and energy balance into the soil-plant-atmosphere continuum system was developed to simulate evapotranspiration; an experiment was conducted using lysimeters at the Experimental Station of Tibet Agricultural and Animal Husbandry University to measure the evapotranspiration of the barley during its growing season in 2019, 2021, 2022 and 2024 for model validation.【Result】The Nash-Sutcliffe efficiency coefficient between evapotranspiration measured and simulated using the model was higher than 0.747, with mean and standard deviation errors less than 5% and 10%, respectively. Compared to evapotranspiration calculated using the Penman-Monteith formula, the proposed model improved the Nash-Sutcliffe efficiency coefficient by 88.6%, reduced the relative root mean square error, systematic and total deviations by 25.9%, 55.1% and 22.3% respectively. In the study area, both the evapotranspiration of barley and its variability were significantly higher than those estimated by the Penman-Monteith formula. When soil moisture was sufficient to meet the demand of the barley, global sensitivity analysis revealed that the influence of the parameters characterizing climate and energy conversion on the evapotranspiration was significantly greater than that of other driving factors, such as net radiation and flux transmission parameters. The hydrology-energy relationship and energy balance had a substantial influence on the evapotranspiration of barley in the plateau. 【Conclusion】The proposed model accurately captured the fundamental mechanisms controlling the evapotranspiration of barley in the Tibetan Plateau, and can be used to simulate spatiotemporal changes in evapotranspiration of other crops in the region.

The balance between water supply and demand is essential for industrial growth, affecting economic, social, and environmental sustainability. Our research employs a Gaussian process regression for demand prediction. Additionally, it takes into account water limits and policy thresholds when determining the supply, thereby defining a range of uncertainty for both the industrial demand and the supply. A pattern recognition method matches this trade-off range, identifying three patterns to support water management. The study focuses on the analysis of industrial water supply and demand dynamics under uncertain conditions in nine cities (Baiyin, Dingxi, Gannan, Lanzhou, Linxia, Pingliang, Qingyang, Tianshui, and Wuwei) in Gansu Province of China’s Yellow River Basin in 2030. The results of the study show that industrial water use in Baiyin, Linxia, Dingxi, and Tianshui cities falls into Pattern I, providing water resources to support industrial development. Industrial water use in Wuwei, Pingliang, Qingyang, and Gannan cities represents Pattern II, which maintains a balance between supply and demand while allowing flexibility in water demand. Finally, the industrial water use in Lanzhou city is characterized by Pattern III, which requires optimization through structural, technological, and management improvements to mitigate the negative impacts of water scarcity on the sustainable development of the economy and society. The results of the research can be used as a reference for policy making in water resources planning and management in the basin.

Quantification of river flood risks is a prerequisite for floodplain management and development. The lower Yellow River (LYR) is characterized by a complex channel–floodplain system, which is prone to flooding but inhabits a large population on the floodplains. Many floodplain management modes have been presented, but implementation effects of these management modes have not been evaluated correctly. An integrated model was first proposed to evaluate the flood risks to people’s life and property, covering an improved module of two-dimensional (2D) morphodynamic processes and a module of flood risk evaluation for people, buildings and crops on the floodplains. Two simulation cases were then conducted to validate the model accuracy, including the hyperconcentrated flood event and dike-breach induced flood event occurring in the LYR. Finally, the integrated model was applied to key floodplains in the LYR, and the effects of different floodplain management modes were quantified on the risks to people’s life and property under an extreme flood event. Results indicate that: ① Satisfactory accuracy was achieved in the simulation of these two flood events. The maximum sediment concentration was just underestimated by 9%, and the simulated inundation depth agreed well with the field record; ② severe inundation was predicted to occur in most domains under the current topography (Scheme I), which would be alleviated after implementing different floodplain management modes, with the area in slight inundation degree accounting for a large proportion under the mode of “construction of protection embankment” (Scheme II) and the area in medium inundation degree occupying a high ratio under the mode of “floodplain partition harnessing” (Scheme III); and ③ compared with Scheme I, the high-risk area for people’s life and property would reduce by 21%–49% under Scheme II, and by 35%–93% under Scheme III.

Drought may be exacerbated by global warming, but drought projections are largely inconsistent. The existing frameworks cannot adequately quantify the robustness and uncertainty of drought projections. Therefore, this study proposes a framework to solve this problem and verifies it in the Chinese Mainland. This framework consists of three main components: (1) the meteorological drought in the 21st century is projected using an impact propagation modelling chain; (2) the robustness of drought projections is quantified using Identical Trend Percentage (ITP) and Signal-to-Noise Ratio (SNR); (3) the uncertainty of drought projections is investigated using improved multi-way analysis of variance. The study reveals that this framework can include more uncertainty sources, investigate the propagation patterns of uncertainty components and quantify the robustness of drought projections. The results show that drought projections are not robust. Specifically, the mean ITP ranges from 49% to 69%, indicating that nearly half of the projections display trends opposite to those of the mean values. In addition, the mean SNR of drought projections ranges between -0.36 and 0.15, with an absolute value far from 1.0. The dominant uncertainty source is the choice of drought index, of which the mean relative contribution ranges between 47% and 61%. When propagating along with the impact propagation modelling chain, the relative importance among existing uncertainty sources usually remains stable if no new physical quantities are joining in. If the relative importance among the existing uncertainty sources for one particular quantity is different from that for the other quantity, the relative importance among the existing uncertainty sources may be adjusted when the two quantities are pooled together by the newly joined processes. Excluding unreasonable drought indices generally reduces the uncertainty and improves the robustness of drought projections; however, it is insufficient to derive robust drought projections.

The ongoing changes in climate and the rapid pace of urbanization are contributing to an alarming increase in the prevalence of urban flooding, which is having a profound impact on the quality of life for residents and the smooth functioning of urban areas. The 1D–2D coupled model is an effective tool for simulating the process of urban flooding, thereby providing a scientific basis for urban planning, flood prevention, and mitigation strategies. The values of numerous parameters within the model not only influence the computational efficiency but also influence the precision of the simulation outcomes. It is of particular significance to ascertain the sensitivity of model parameters. In this study, a 1D–2D coupled model of urban flooding was constructed, and a parameter sensitivity analysis was conducted using the modified Morris method and the Sobol method in two ways, with the amount of waterlogging as the target. The findings indicate that the minimum infiltration rate is the most sensitive parameter in the local sensitivity analysis, whereas the Manning coefficient of the permeable surface area is the most sensitive in the global sensitivity analysis. The research outcomes can facilitate the optimization of the model parameters and enhance the precision and dependability of the model predictions, thereby providing more accurate data support for urban flooding early warning and emergency response.

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

Ecological restoration projects have significantly altered the environment of China’s Loess Plateau. However, the interaction and relative importance of the underlying natural and socioeconomic drivers remain poorly understood. Thus, this study employed the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, the Optimal Parameters-based Geographical Detector (OPGD) model, and Structural Equation Modeling (SEM) to assess the evolution of habitat quality (HQ) and its driving factors in the Yanhe River Basin from 1980 to 2020.The results indicate that HQ followed a sigmoidal (S-shaped) trajectory over time and exhibited significant spatial clustering (P < 0.001). It was positively correlated with the expansion of woodland and grassland but strongly negatively correlated with cultivated land and build-up land (P < 0.001). Among the drivers, population density (POP) and gross domestic product (GDP) were key factors exerting strong negative effects (path coefficients of −0.23 and −0.41, respectively), whereas the normalized difference vegetation index (NDVI) and slope showed significant positive effects (path coefficients of 0.17 and 0.23, respectively). Precipitation (PRE) indirectly improved HQ by enhancing NDVI. Furthermore, higher PRE, steeper slope, and higher GDP amplified the positive effect of NDVI, while lower PRE intensified the negative impact of human activities. In summary, ecological restoration projects markedly improved HQ in the basin, underscoring the synergistic roles of natural conditions and socioeconomic factors in shaping environmental outcomes.

To improve the comprehensive benefits of the Xiaolangdi Reservoir in gaming among multi-objectives during the flow and sediment regulation processes before flood seasons,an integrated model has been proposed,which can simulate the flow-sediment transport in the reservoir area and quantitatively evaluate the comprehensive benefits of reservoir operation.The integrated model consists of three sub-modules,including:a flow-sediment transport module,which considers the process of turbidity currents and flow exchanges between the mainstream and tributaries;a reservoir regulation module,which serves as a connection between the flow-sediment simulation in the reservoir area and the calculation of channel deformation volume in the Lower Yellow River;a ben-efit evaluation module,which adopts an economic indicator to measure the comprehensive benefits.Flow and sediment regulation e-vents in the Xiaolangdi Reservoir in 2013 and 2014 were used for model calibration and verification,showing that the whole proces-ses of plunging,transport and venting of turbidity current,as well as the outflow and power generation processes,were in good a-greement with the measured data.Key operation parameters were selected based on the practical experience of flow-sediment regula-tion events over the years.Based on the 2014 actual operation process,5 new operation schemes were designed by reducing the connecting water level or decreasing the degree of backwater,and comprehensive benefits of these five operation schemes were as-sessed.Calculation results showed that the changes of connecting water levels and backwater conditions in a reservoir regulation process would have a conflict between sedimentation reduction and water conservancy.By comparing the economic indicators of de-signed operation schemes,the operation scheme with the connecting water level of 222.57 m and less backwater has been suggested for gaining higher comprehensive benefits in the Xiaolangdi Reservoir.

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

Water, soil, and heat are strategic supporting elements for human survival and social development. The degree of matching between human-land-water-heat elements directly influences the sustainable development of a region. However, the current evaluation of the matching of human-land-water-heat elements overlooks the influence of elevation factors on the matching results, especially evident in mountainous areas. Taking the Yunnan Plateau with distinctive mountainous features as the research subject, divided into 11 elevation ranges, the Lorenz Gini coefficient, asymmetry coefficient, matching distance, and imbalance index are used to assess the spatial matching and balance of human-land-water-heat elements. A projection tracing model is employed to analyze its water resource carrying capacity. Analyses revealed that the Gini coefficient of monthly precipitation from the 1950s to 2022 on the Yunnan Plateau increases with increasing latitude, whereas the correlation with elevation is notably lower. The asymmetry coefficient increases gradually from west to east with change in longitude. The mismatch of the human–land–water–heat system in regions at different elevations is in the order 1800–2000 m > 2000–2200 m > 1400–1600 m > 800 m > other areas. The matching of the human–land–water–heat system in different wet–dry years and seasons also fluctuates with elevation, resulting in serious seasonal drought and water shortage problems in mountainous areas with elevations of 1200–1600, 1800–2000 m, and >2600 m. The spatial equilibrium of temperature and precipitation in regions of different elevations is best, followed by that of cultivated land, while that of the population is the worst. The Gini coefficients for different water cycle processes of precipitation, surface runoff, and regulating storage capacity for water supply continue to increase. Specifically, the Gini coefficient of industrial water supply is the highest, reaching 0.576, and that of agricultural irrigation is the lowest (0.424). Through artificial regulation of lake and reservoir water, seasonal changes in the demand for agricultural irrigation water are offset to achieve a demand–supply balance and matching of land and water resources. The water resource capacity of different elevation ranges is evenly underloaded. However, the potential of the water resource capacity varies obviously with elevation in the order 2000–2200 m < 1800–2000 m < 1600–8000 m < 1400–1600 m < other areas. It appears that the greater the human–land–water–heat system mismatch, the smaller the regional potential of the water resource capacity.

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.

Study region: The source area of the Yangtze River, a typical catchment in the cryosphere on the Tibet Plateau, was used to develop and validate a distributed hydrothermal coupling model. Study focus: Climate change has caused significant changes in hydrological processes in the cryosphere, and related research has become hot topic. The source area of the Yangtze River (SAYR) is a key catchment for studies of hydrological processes in the cryosphere, which contains widespread glacier, snow, and permafrost. However, the current hydrological modeling of the SAYR rarely depicts the process of glacier/snow and permafrost runoff from the perspective of coupled water and heat transfer, resulting in distortion of simulations of hydrological processes. Therefore, we developed a distributed hydrothermal coupling model, namely WEP-SAYR, based on the WEP-L (Water and energy transfer process in large river basins) model by introducing modules for glacier and snow melt and permafrost freezing and thawing. New hydrological insights for the region: In the WEP-SAYR model, the soil hydrothermal transfer equations were improved, and a freezing point equation for permafrost was introduced. In addition, the glacier and snow meltwater processes were described using the temperature index model. Compared to previously applied models, the WEP-SAYR portrays in more detail glacier/ snow melting, dynamic changes in permafrost water and heat coupling, and runoff dynamics, with physically meaningful and easily accessible model parameters. The model can describe the soil temperature and moisture changes in soil layers at different depths from 0 to 140 cm. Moreover, the model has a good accuracy in simulating the daily/monthly runoff and evaporation. The Nash-Sutcliffe efficiency exceeded 0.75, and the relative error was controlled within +/- 20 %. The results showed that the WEP-SAYR model balances the efficiency of hydrological simulation in large scale catchments and the accurate portrayal of the cryosphere elements, which provides a reference for hydrological analysis of other catchments in the cryosphere.