Snowmelt observations at the slope scale and implications for the catchment response using the Alpine3D model

Snowpack and especially its melt during spring is a crucial resource for water availability in mountainous regions. A better understanding of the processes and their representation in hydrological models is therefore necessary for different purposes, such as water management, flood forecast or hydropower production. However, this remains a challenge given the complexity of the controlling processes and their relative interactions. In this study, we analyze data from snowmelt lysimeters in a small alpine catchment, the Dischma river basin (~40 km2) near Davos, Switzerland. The objective is to study relationships between snow ablation and its driving processes, morphology and watershed response. The overall goal is to improve snowmelt processes representation in distributed hydrological models. Four measurement stations installed on representative slopes monitored continuously the snowpack temperature profile, snowpack liquid water output, and soil moisture throughout the melting season. The catchment response is measured at three stream gauges, the first one at the watershed outlet and the two others at specific sub-basins outlets. The results for the water year 2015 will be presented: our analysis focuses on the snowmelt lysimeters data and the implication for the stream flow. These measurements are compared to model results obtained from the spatially distributed and physically based model Alpine3D (Lehning et al., 2006) and its recent hydrological extension StreamFlow (Gallice et al., 2016). We will notably discuss the influence of the liquid water transport scheme within the snowpack on the snowmelt response, and the spatio-temporal snow distribution over the catchment.