Expected Future Runoff of the Upper Jordan River Simulated with a CORDEX Climate Data Ensemble

Data from five different RCMs run in two experiments from the Coordinated Regional Climate Downscaling Experiment (CORDEX) are applied together with the Water Flow and Balance Simulation Model (WaSiM) to assess the future availability of water in the upper Jordan River. Simulation results for 1976–2000 show that the modeling system was able to reasonably reproduce the observed discharge rates in the partially karstic complex terrain without bias correction of the precipitation input. For the future climate in the area, the applied CORDEX models indicate an increasing annual mean temperature for 2031–60 by 1.8 K above the 1971–2000 mean and by 2.6 K for 2071–2100. The simulated ensemble mean precipitation is predicted to decrease by 16.3% in the first period and 22.1% at the end of the century. In relation to the mean for 1976–2000, the discharge of the upper Jordan River is simulated to decrease by 7.4% until 2060 and by 17.5% until 2100, together with a reduction of high river flow years.