Impacts of Climate Change on Low Flows at Tang Panj Sezar Subbasin, Southwest of Iran

Any change in characteristics of low flows under climate change may have important effects on various socioeconomic, environmental, water resource, and governmental planning aspects. The aim of this research was to use various low-flow indices to investigate low flows for a future period (2015-2044) under the effects of climate change for the case of Sezar basin, southwestern Iran. In this research, outputs of 10 atmosphere-ocean general circulation models (AOGCMs) under an A2 emissions scenario were used to predict temperature and precipitation scenarios under climate change. The low-flow indices used in this study included those extracted from a flow duration curve (discharges exceeded 70, 90, and 95% of the time, i.e., Q(70), Q(90), and Q(95)), indices of low-flow frequency analysis (annual minimum 7-day flow with 2, 10, 20, and 100 return periods, i.e., AM7(T=2), AM7(T=10), AM7(T=20), and AM7(T=100)), and flow deficit characteristics (number of dry days in a year, maximum length of dry period, deficit volume, and deficit intensity). The results indicated that the status of low flow in the future will be better than the baseline (1971-2000) in all subbasins, so values of indices including Q(70), Q(90), and Q(95) as well as AM7(T=2), AM7(T=10), AM7(T=20), and AM7(T=100) will increase and values of indices of deficit volume and intensity will decrease. The results also showed consistency between the indices derived from the flow duration curve and deficit characteristics, whereas indices of frequency analysis were determined to be inherently different. (C) 2017 American Society of Civil Engineers.