Runoff modelling of the glacierized Alpine Upper Salzach basin (Austria): multi‐criteria result validation

Abstract

Abstract:Snow cover and glaciers are the most important long-term forms of water storage and, hence, the main sources of runoff during the ablation period for many alpine headwater basins. We therefore investigated the application of the conceptual, distributed hydrological precipitation runoff evapotranspiration hydrological response unit model (PREVAH) to the alpine glacierized headwater basin of the Upper Salzach (593 km 2 , 5% glacierized) river in Austria. Hourly meteorological data from 17 stations for a 6-year period were available for the calibration and validation of the hourly runoff simulations. Multi-criteria validation included hourly discharge, snow covered area (SCA), and glacier mass balances. SCA maps were generated from optical satellite images for six dates. These maps were compared to simulated maps of SCA to (1) calculate differences in SCA, (2) calculate altitudinal differences, and (3) show the ability to accurately model snow cover on different aspects. The differences between observed and simulated SCA for glacierized areas were between 1 and 9% during June and July, and between 10 and 36% during August and September observations. In general, the model overestimated SCA, which is the result of PREVAH not including redistribution of snow by wind or avalanches. The temporal variability of the simulated mass balance agreed well with observations from surrounding glaciers. Nash-Sutcliffe Efficiency Criteria (R 2 ) of the hourly discharge simulations were between 0Ð83 and 0Ð89 with the exception of the extreme summer of 2003 which had an R 2 of 0Ð74. Contributions of glacier melt (firn/ice melt) to annual total runoff were between 1 and 4%. Again, the exception was 2003, when glaciers contributed 15% of the annual runoff and 60% to the August runoff alone.

Stable water isotope variation in a Central Andean watershed dominated by glacier and snowmelt

“…For a basin with a glacier cover of 11.5 %, this contribution is high, compared to published results from glacierised basins in other areas (Jost et al, 2012;Koboltschnig et al, 2008;Stahl and Moore, 2006;Verbunt et al, 2003;Zappa and Kan, 2007). It is also high compared to modelled results of the Juncal basin by Ragettli and Pellicciotti (2012), although the results are difficult to compare as their model was applied during relatively wet years.…”

Comparative Assessment of Runoff and Its Components in Two Catchments of Upper Indus Basin by Using a Semi Distributed Glacio-Hydrological Model

“…The isotopic investigation cannot be used extensively as it requires large financial and laboratory support. However, the application of hydrological models to understand the glacier effects in hydrology is comparatively new and more commonly used (Hagg et al, 2007;Huss et al, 2008;Koboltschnig et al, 2008;Prasch, 2010;Nepal et al, 2013). But the main problem is the availability of long term data of high quality to symbolize the hydrological dynamics of Upper Indus Basin (UIB).…”

Glacier and runoff changes in the Rukhk catchment, upper Amu-Darya basin until 2050

“…A variety of conceptual runoff models were used by many different authors in glacierized catchments (e.g. Hock, 2003;Verbunt et al, 2003;Schaefli et al, 2005;Juen et al, 2007;Konz et al, 2007;Koboltschnig et al, 2008), also in combination with glacier area development based on area-volume scaling (Stahl et al, 2008) or by parameterizations using ice thickness change patterns . In high elevations, where a comparable big fraction of runoff is formed by snow-and ice-melt, conceptual degree-day models have the advantage that melt can be described much more easily than precipitation.…”