The effect of RCP scenarios on hydrological parameters, case study: Doiraj Dam catchment

The effect of RCP scenarios that have recently been analyzed in Iran is the results of (AR5) Intergovernmental Committee climate change (IPCC) that indicated the amount of rainfall, temperature in the upcoming period compared to the base period. In this study, changes in precipitation and temperature and the effect of these parameters on the amount of runoff in the period 2016-2044 Doiraj Dam is considered. The amount of monthly temperature and precipitation models ACCESS1-0, BCC-CSM1.1, CANESM2, BNU-ESM, and CSIROK3-5-0 under the scenario RCP8.5 was prepared for the region. Then, Change Factor method of spatial and temporal downscaling is used for the study area. The temperature, precipitation and discharge values were intered to IHACRES model and after calibration and validation, the future runoff was simulated in this period. For hydrological drought analysis, frequency analysis, SWSI, SDI, SRI and threshold indices were calculated. The results showed an increase of 1.29 degrees Celsius of temperature and 1.28 percent in precipitation in 2016-2044 compared to 1987-2015. River flow has also increased by 4.9 percent compared to the baseline. The frequency analysis of annual runoff is obtained in futhure with return periods of 50 and 100 years 13.90 and 15.06 m3s-1 , respectively. Quantitative analysis of drought indices showed that in years 1996, 1998 and 2004 there was no drought and in 2008, 2009, 2011 and 2012 there was drought occurance. Also, in future periods of 2024, 2025, 2033 and 2035 drought conditions are very poor and in years 2020, 2029, 2037 and 2041 drought is evident. Also, checking the volume threshold method with the Q70 threshold showed that in the years 2037-2038 and 2040-2041 significant hydrological drought will happen with the lack of 64.2 million m3.