Assessment of climate change under CMIP5-RCP scenarios on downstream rivers glaciers – Sardabrud River of Alam-Kuh glacier, Iran

Abstract

ABSTRACTEstimates of the impact of climate change on Sardabrud River located downstream of Alam-Kuh glacier in northern Iran, ultimately draining into the Caspian Sea, are described. In this research, the GCMs’ projection data with CMIP5 scenarios have been used to predict the situation of this River over the two next decades. Projected data using GCMs (EC-EARTH, GFDL-CM3, HadGEM2-ES, MIRO-C5 and MPI-ESM-MR) for the period of 2021–2040 are employed with a 35-year observation period of 1984–2014. For data downscaling the LARS-WG method on its version 6.0 was used. Identification of the lowest error indicates (including RMSE and R2) were used to find the model with the best fit to projections from the historical period; the EC-EARTH model was used to show the changes in the basin’s flow to the Sardabrud River in the period 2021–2040. Results from a conceptual glacier-hydrologic model (GSM-SOCONT) for joint simulation of daily discharges of the glacier are described. Despite a predicted 6% decrease in precipitation, the results point to an increase of 10% in flows in the Sardabrud River, meaning there is definitive evidence of reduction of annual glacier mass due to increasing temperatures and the melting of the glacier, as caused by climate change.