Tracing Snowmelt Paths in an Integrated Hydrological Model for Understanding Seasonal Snowmelt Contribution at Basin Scale

Abstract

AbstractSnowmelt contributions to water resources in cold regions are receiving increasing attention. However, there are clear challenges to accurately distinguish the snowmelt contributions to different hydrological processes in seasonal snow regions. Here, we present an improved method to evaluate snowmelt contributions by tracing the snowmelt flow paths in different media based on a distributed geomorphology‐based ecohydrological model coupled with a physically based snow module. The calculated snowmelt contribution is not limited to river discharge but is also applicable to evaporation and soil storage. The study region, the upstream Heihe River (UHR) basin, is located in the northeastern Tibetan Plateau. Our results indicate that snowmelt can continuously contribute to hydrological processes throughout the year because most of the snowmelt remains in soil voids, even on snow‐free days. In UHR, the snowmelt contribution to total runoff on snow days accounts for a minor part of the total snowmelt contribution, and the snowmelt contribution on snow‐free days accounts for a major part of the total. There is notable snowmelt retention in the soil in each year, which continues to supply discharge into next year. Our results also indicate that the role of snowmelt contribution to annual discharge could be gradually weakened if rainfall more greatly increases the summer discharge in the UHR basin. The improved evaluation method will contribute to a more comprehensive assessment of snowmelt contributions to hydrological processes in seasonal snow regions.