Assessing vulnerability to climate change for total organic carbon in a system of drinking water supply

Evaluation of the impact of climate change on water sectors is one of the most important challenges of water resources management in the current century. In this paper, assessment of vulnerability to climate change on total organic carbon (TOC) concentration in the Jajrood catchment in Tehran has been done. The hydroclimatologic parts of the assessment have been done by implementing HYMOD and downscaling of precipitation, temperature and evaporation using statistical downscaling model (SDSM). Three climate change scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) from the Canadian Earth System Model have been used to project climate change (2006 to 2050). Moreover, different linear models were used to model water quality in Latyan Dam and Tehranpars Water Treatment Plant (TWTP). Based on the results, the average annual simulated rainfall under RCP 2.6, RCP 4.5, and RCP 8.5 are 670.2, 658.06 and 650.93 mm, respectively. The projected streamflow under the scenarios were 97%, 90%, and 92%, respectively, more than observation period. The average simulated TOC concentration in influent water was 52.43 (mg/L), which was about seven times more than the averaged observed value (8.78 mg/L). The most important byproduct of the current impact assessment is to define an adaptation action plan, because the TWTP will not be able to provide drinking water standards in this area.