The Impact of Climate Change on Dorudzan Dam Inflow and Reservoir Volume, Northern Fars Province

The Dorudzan dam inflow is assessed using SWAT under climate change. The daily simulated precipitation and temperature data by 22 general circulation models under RCP2.6, RCP4.5 and RCP8.5 are downscaled at five climatic stations using LARS-WG statistical model and transient change factors approach. The precipitation over the watershed will decrease from 668 mm during the observation period to 572, 509 and 529 mm under the RCP2.6, RCP4.5 and RCP8.5, respectively (14.4%, 23.8% and 20.8%). The mean annual evapotranspiration will increase by 30%-36% due to increased mean annual temperature by 1.7-3.3 ℃ under three RCPs. The mean annual inflow will decrease from 28.6 m3/s to 16.7, 11.44 and 12 m3/s under the RCP2.6, RCP4.5 and RCP8.5, respectively (42%, 60% and 58%). The mean monthly reservoir volume will decrease from 490 MCM to 350, 232 and 247 MCM under the RCP2.6, RCP4.5 and RCP8.5, respectively while the dam outflow will decrease from 60 MCM/month to 43.3, 29 and 30.9 MCM/month, respectively due to the precipitation reduction by 160 mm (24%) and evapotranspiration increase by 100 mm (36%) over the watershed. The reduction of reservoir volume will intensify the downstream water shortage and crisis in the future.