PDF · Útgáfa 2021-RD-01 — desember 2021Impact of climate change on mean and high streamflow characteristics in Icelandic watersheds: a case study.
This study presents an analysis of the hydrological response of three river catchments in Iceland to projected climate change in the 21st century. The catchments are located in the southeast (Geithellnaá), northeast (Selá) and northwest (Vatnsdalsá) of the country and their current hydrological regimes are strongly influenced by snowmelt seasonality. Daily streamflow series were simulated over the period 1981-2100 with the HYPE hydrological model forced with an ensemble of regional climate scenarios. Changes affecting near surface air temperature and precipitation and their impact on mean and extreme streamflow characteristics were analysed. The results suggest that if projected climate scenarios realise, temperature will increase over the next decades and lead to shorter snow seasons combined with less snow accumulation. These changes will in turn impact the hydrological regimes of all studied catchments and lead to a streamflow increase in autumn/winter and a streamflow decrease in spring/summer. The flood regimes of these catchments will also be impacted by the projected warming. In the Vatnsdalsá and Selá catchments, where annual maximum floods are mostly observed in spring in the present climate, a decrease in the magnitude of these extreme events is projected and at the same time, they will gradually tend to occur less frequently in spring and increasingly more frequently in autumn/winter. The Geithellnaá catchment is projected to remain under the main influence of autumn floods and a slight magnitude increase is possible.
