Influence of Slope‐Scale Snowmelt on Catchment Response Simulated With the Alpine3D Model

Abstract

Snow and hydrological modeling in alpine environments remains challenging because of the complexity of the processes affecting the mass and energy balance. This study examines the influence of snowmelt on the hydrological response of a high‐alpine catchment of 43.2 km2 in the Swiss Alps during the water year 2014–2015. Based on recent advances in Alpine3D, we examine how snow distributions and liquid water transport within the snowpack influence runoff dynamics. By combining these results with multiscale observations (snow lysimeter, distributed snow depths, and streamflow), we demonstrate the added value of a more realistic snow distribution at the onset of melt season. At the site scale, snowpack runoff is well simulated when the mass balance errors are corrected (R2 = 0.95 versus R2 = 0.61). At the subbasin scale, a more heterogeneous snowpack leads to a more rapid runoff pulse originating in the shallower areas while an extended melting period (by a month) is caused by snowmelt from deeper areas. This is a marked improvement over results obtained using a traditional precipitation interpolation method. Hydrological response is also improved by the more realistic snowpack (NSE of 0.85 versus 0.74), even though calibration processes smoothen out the differences. The added value of a more complex liquid water transport scheme is obvious at the site scale but decreases at larger scales. Our results highlight not only the importance but also the difficulty of getting a realistic snowpack distribution even in a well‐instrumented area and present a model validation from multiscale experimental data sets.

The Importance of Near-Surface Winter Precipitation Processes in Complex Alpine Terrain

“…Snow accumulation patterns were found to be very persistent for different winters and were found to be dominated by few major snowfall events (Schirmer et al 2011). Given the interannual variability or even a shift in prevailing wind directions going along with climate change, future snow accumulation may look different with implications for local ecology, avalanche danger, and runoff formation (e.g., Brauchli et al 2017). FEBRUARY 2019 G E R B E R E T A L .…”

Hydrologic connectivity at the hillslope scale through intra‐snowpack flow paths during snowmelt

“…Improved understanding of the spatio-temporal variability in meltwater outflow from intra-snowpack flow paths also stands to benefit hydrologic modelling in snow-dominated basins where properly representing the scale of hydrologic processes is essential (Blöschl, 1999). As data retrieval methods improve and higher resolution products become available (Bühler, Adams, Bosch, & Stoffel, 2016;Nolan, Larsen, & Sturm, 2015;Painter et al, 2016), modelling efforts will similarly increase in resolution (Brauchli, Trujillo, Huwald, & Lehning, 2017;Hedrick et al, 2018). Hydrologic models often assume snowmelt infiltrates vertically into the soil through one-dimensional intra-snowpack percolation occurring uniformly across a grid cell or lumped hydrologic response unit (e.g., Kormos et al, 2014;Wever, Comola, Bavay, & Lehning, 2017).…”

High-resolution hydrometeorological modelling of the June 2013 flood in southern Alberta, Canada

“…CC BY 4.0 License. al., 2003) that influence winter snow accumulation and runoff generation in mountainous catchment (DeBeer and Pomeroy, 2017;Brauchli et al, 2017).…”