Modeling of water balance response to an extreme future scenario in the ?tztal catchment, Austria

摘要

The aim of the study was to investigate the impact of climate change on thewater balance of the ?tztaler Ache catchment in Tyrol, Austria. For thispurpose the conceptual hydrological model HBV-D REG was applied. First, themodel was calibrated and validated using current observed climate anddischarge data. Second, the calibrated model was applied with reanalysisdata. Third, downscaled climate scenarios from 2010 to 2099 served as inputdata to the HBV-D REG. Thereby two extreme land cover scenarios wereconsidered: for water balance modeling a constant glacier coverage from todayand additionally for runoff simulations a complete loss of glaciered area.The downscaled climate data were generated with the expanded downscalingmethod. Scenario simulations indicated an increase in annual arealtemperature by 3.4 °C and a slight decrease in annual arealprecipitation by 89 mm in the next one hundred years. According to the hydrologicalmodeling, these climate changes caused an increase in evapotranspiration anda decrease in snow coverage. Furthermore model simulations showed an increasein winter and spring runoff, whereas summer runoff was highly sensitive toglacier coverage and decreased with complete loss of glacier coverage.