Enhancing runoff-infiltration partitioning in the SVS land surface model improves streamflow simulations under frozen soil conditions

Enhancing runoff-infiltration partitioning in the SVS land surface model improves streamflow simulations under frozen soil conditions

Surface runoff and soil evaporation dominate the sensitivity of land surface models to soil parameters

Integrated analysis of surface water-groundwater interactions and enhanced hydrological forecasting of glacierized river in cold and arid regions

In cold and arid regions, climate change has altered precipitation patterns and accelerated glacierized retreat, which imposes severe risks on the stability of regional hydrological systems. Combined with the strong interactions between surface water (SW) and groundwater (GW) regulated by distinctive geological conditions, clarifying the baseline hydrological regime and predicting future hydrological changes is critical to maintaining local ecosystem stability. The headwater catchment of the Bortala River in Northwest China represents a typical glacierized watershed dominated by spring-fed discharge. Under the continuous influence of climate change, quantitative investigations into surface water-groundwater interactions in this catchment are still inadequate. In this study, a coupled SWAT-MODFLOW model embedded with a glacier module was developed to clarify the surface water-groundwater interactions relationship. Based on the Budyko framework, under CMIP6 climate scenarios, to establish an optimized decomposition and reconstruction simulation system, furthermore, to explore the changing characteristics of temperature, precipitation, and runoff. Observed hydrometeorological parameters were utilized to calibrate and validate the established model. A set of statistical indices was employed to assess the modeling performance, and the coupled model attained favorable simulation accuracy. The main results indicated that although surface water served as the dominant recharge source for groundwater from 1971 to 2020, representing a cumulative reduction of 26.7% from the initial value of the historical period, and an increased average annual decline rate of 0.45%. Future scenario projections revealed an increasing trend in total watershed runoff under both SSP2-4.5 and SSP5-8.5, with growth rates of 13.6% and 14.2%, respectively. A runoff inflection point is projected to occur around the 2070s (± 10 years), which will appear approximately 10 years earlier under the high-emission SSP5-8.5 scenario. In addition, intensified precipitation extremes may trigger severe hydrological risks, which are expected to concentrate around the 2040s and 2070s. The SWAT-MODFLOW model quantifies surface water-groundwater interactions in the glacial-snowmelt recharge system of the spring river, advancing hydrological modelling in cold-arid regions. Within the Budyko framework, the modified Choudhury-Yang equation combines temperature change and glacial-snowmelt recharge to analyze the spring river. CMIP6-driven SWAT-MODFLOW enhances runoff forecasting for the spring river. Combined with the SSP2-4.5 and SSP5-8.5 scenarios, it predicts future variations in temperature, precipitation, and runoff, identifies hydrological change inflection points, and provides a basis for flood prevention and water resources management. The SWAT-MODFLOW model quantifies surface water-groundwater interactions in the glacial-snowmelt recharge system of the spring river, advancing hydrological modelling in cold-arid regions. Within the Budyko framework, the modified Choudhury-Yang equation combines temperature change and glacial-snowmelt recharge to analyze the spring river. CMIP6-driven SWAT-MODFLOW enhances runoff forecasting for the spring river. Combined with the SSP2-4.5 and SSP5-8.5 scenarios, it predicts future variations in temperature, precipitation, and runoff, identifies hydrological change inflection points, and provides a basis for flood prevention and water resources management.

Process diagnostics of snowmelt runoff in global hydrological and land surface models – Part 1: A systematic evaluation across basins of increasing complexity

Abstract. Accurate simulation of snowmelt runoff (SMR) is critical for water resource management. However, despite the abundance of global hydrological models, little is known about their SMR performance. This study presents a comprehensive evaluation of SMR across 15 state-of-the-art large-scale models and runoff products by focusing on their biases in first-order indices, i.e., the total volume (Qsum), peak flow (Qmax), and centroid timing (CTQ) of runoff in the snowmelt period. Then by introducing 1455 snow-dominated basins with diverse topography and vegetation complexities, we further proposed a novel model robustness metric to test how different models perform under increasing basin complexity, thereby allowing for a quantification on how they adapt to complex environmental conditions. Our results reveal that (1) most models exhibit underestimated Qsum and Qmax and predict CTQ too early. These biases are particularly pronounced in regions such as the western United States, northern Europe, and northeastern China. (2) Model biases systematically increase with basin complexity, with CTQ exhibiting strong sensitivity to mean elevation and topographic variability, while Qsum and Qmax being shaped more by mean elevation and the diversity of vegetation types in the basin. (3) The robustness assessment further shows that observation-constrained runoff products exhibit the most outstanding performance (i.e., low biases and strong adaptability to stern conditions), followed by the hydrological and land surface models. Notably, while global hydrological models generally exhibit stronger robustness in simulating Qsum and Qmax, land surface models show a clear advantage in simulating CTQ, highlighting their structural strength in capturing melt timing rather than runoff magnitude. This study provides a large-sample benchmark for SMR evaluation and complements existing model assessment approaches by examining model performance across basin complexity gradients, offering useful insights for future model development and uncertainty reduction.

Compound Hydro-Geomorphic Hazards in European Mountain Regions: A Roadmap for Research on Postfire and Frozen Soil Dynamics

Mountain regions in Europe increasingly face compound runoff-related hazards under a changing climate. This article compares postfire surface runoff (PFSR) and frozen-soil surface runoff (FSSR), 2 processes typically studied separately but sharing key meteorological triggers, as well as initiation and propagation mechanisms. Both are triggered by short, high-intensity rainfall acting on infiltration barriers: hydrophobic layers in burned soil and pore ice in frozen soil. Despite distinct thermal and seasonal contexts, PFSR and FSSR exhibit convergent process chains characterized by reduced interception, limited infiltration, surface ponding, and efficient sediment entrainment. Their occurrence increasingly transcends expected seasonal regimes, reflecting climate-driven shifts in fire activity, snow dynamics, and freeze–thaw cycles. Building on these parallels, this study proposes a research framework and outlines a future research agenda that links mapping, monitoring, experimentation, modeling, and governance. It advocates integrated observation networks combining remote sensing and in situ techniques, controlled experiments to quantify thermohydraulic and erosional processes and changes in vegetation cover, and physical models capturing preferential flow and transient infiltration barriers. For risk management, the article stresses predictive early warning systems that provide sufficient lead time to manage evacuations and infrastructure protection. By identifying shared mechanisms and converging research needs, this contribution supports a future research agenda and cross-disciplinary strategies for mitigating emerging compound hazards in alpine environments.

Assessing soil erosion and sediment transport efficiency under climate change and land-use dynamics: a multi-temporal approach in the taleghan watershed