Using ECHAM5 General Circulation Model and Hydrological Lumped Model GR2M to Assess Impacts of Climate Change on Runoff

Abstract

In the study presented, the impacts of climate change on a study region in Turkey were investigated by a modelling strategy including a statistical downscaling model and hydrological lumped model. This strategy was implemented in the way of the climate forecasts of ECHAM5 circulation model cited in the Intergovernmental Panel on Climate Change for the Izmir-Tahtali watershed having Mediterranean climate characteristics. The precipitation and temperature changes on basin have been statistically determined by downscaling the coarse atmospheric variables of A1B and 20C3M scenarios which respectively represent the semi-pessimistic future and present day predictions to monthly areal precipitation and mean temperature. Subsequent to the statistical downscaling analyses, the scenario results were transformed to runoff series by means of the hydrological model GR2M to examine the impacts of temperature and precipitation changes on runoff. According to the A1B climate scenario results of ECHAM5 climate model, approximately 28% decrease on runoff is foreseen for the 2001-2099 period when 20C3M present day scenario results are taken into consideration.