Climate change impacts on streamflow at the upper Jordan River based on an ensemble of regional climate models

Study Region: The upper Jordan River is the major water resource in Israel, a country which suffers from increasing shortage of natural water resources. Study Focus: In this study, we apply for the first time to this area an approach based on an ensemble of regional climate models, verify their trends vs. observations for a control period and use them for simulating future discharges of the Jordan River. New Hydrological Insights for the Region: The results of this study show that the observed negative trend of precipitation for the control period is also simulated by the climate models ensemble and projects a continued decreasing trend to the near future and further into the far future. Using the GR6J daily hydrological model for evaluating the effects of the predicted climate changes on the hydrological cycle in the region shows an increase in potential evaporation and a decrease in streamflow volumes in the Jordan River, Northern Israel. The results reveal and quantify the changes in rainfall–runoff relationships. These changes in the hydrological cycle in the region can be explained by changes in precipitation distribution and duration and decrease in soil moisture caused by the increase in evaporation. Results presented in this study could imply major consequences for the region. The findings here are relevant not only to Israel but also to the surrounding countries. Keywords: Rainfall - runoff relationships, Ensemble of regional climate models, Changes in the hydrological cycl