Abstract
Abstract. In this study, the fully distributed, physically based hydroclimatological model AMUNDSEN is set up for catchments in the highly glacierized Ötztal Alps (Austria, 558 km2 in total). The model is applied for the period 1997–2013, using a spatial resolution of 50 m and a temporal resolution of 1 h. A novel parameterization for lateral snow redistribution based on topographic openness is presented to account for the highly heterogeneous snow accumulation patterns in the complex topography of the study region. Multilevel spatiotemporal validation is introduced as a systematic, independent, complete, and redundant validation procedure based on the observation scale of temporal and spatial support, spacing, and extent. This new approach is demonstrated using a comprehensive set of eight independent validation sources: (i) mean areal precipitation over the period 1997–2006 derived by conserving mass in the closure of the water balance, (ii) time series of snow depth recordings at the plot scale, (iii–iv) multitemporal snow extent maps derived from Landsat and MODIS satellite data products, (v) the snow accumulation distribution for the winter season 2010/2011 derived from airborne laser scanning data, (vi) specific surface mass balances for three glaciers in the study area, (vii) spatially distributed glacier surface elevation changes for the entire area over the period 1997–2006, and (viii) runoff recordings for several subcatchments. The results indicate a high overall model skill and especially demonstrate the benefit of the new validation approach. The method can serve as guideline for systematically validating the coupled components in integrated snow-hydrological and glacio-hydrological models.
Highlights
Assessing the amount of water resources stored in mountain catchments as snow and ice as well as the timing of meltwater production and the resulting runoff is of high interest for glaciological and hydrological investigations and hydropower production
Some studies have used the 250 m visible and near-infrared MODIS bands to classify snow and ice surfaces (e.g., Shea et al, 2013), but we found this method not applicable for our study, since the coarse resolution of the MODIS scenes makes it challenging to differentiate between snow and ice facies for the majority of glaciers in the study area
While some uncertainty can be attributed to the applied snow densification parameterization for the conversion from water equivalent to snow depth, these results show that the applied precipitation corrections considerably improve results especially at high elevations, as can be seen for the station Pitztaler Gletscher
Summary
Assessing the amount of water resources stored in mountain catchments as snow and ice as well as the timing of meltwater production and the resulting runoff is of high interest for glaciological and hydrological investigations and hydropower production. Longer periods of negative glacier mass balances first result in increased runoff due to the enlarged contribution of glacier melt later on, followed by a decline of runoff amounts as a consequence of the reduced glacier area (e.g., Jansson et al, 2003; Beniston, 2003; Collins, 2008; Bliss et al, 2014) For some regions, this moment of “peak water” has already passed, while for others it is expected over the course of the current century (Salzmann et al, 2014; Bliss et al, 2014). They tend to be comparatively parsimonious both in terms of input data and the number of parameters; as the parameters often
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