Assessing the hydrological changes of environmental water rights due to climate change (The case study -Sefidrood river)

Abstract

Background and Objective:Climate change and the lack of logical balance between water supply and demand in various sectors of industry, agriculture and drinking are among the leading challenges in the macro-management of the country's water resources. Therefore, the effects of climate change can be evaluated in various basins, including environmental aspects. The purpose of this study is to investigate the effect of climate change on variations of the hydrological regime (runoff) downstream of Sefidrud Dam and to estimate the minimum environmental flow. Method:In this regard, initially using LARS-WG microscale exponential model, climatic data that affects the runoff under three scenarios RCP2.6, RCP4.5, and RCP8.5 for the period 2021-2080 was determined and introduced as an input to the hydrological model of SWAT to simulate the river flow. Findings:Due to the increasing trend of temperature and precipitation, the amount of runoff in the future period showed an increasing trend as well. Then, using two hydrological methods of the Tenant and flow duration curve, the minimum environmental needs of the river were determined. The obtained values show that the minimum environmental needs of the river will be met according to the results of the tenant method and the flow duration curve in the future.Discussion and Conclusion: The results showed that the flow values obtained by the tenant method were less than the average flow simulation. Despite the high correspondence and coordination of the flow rate from the flow continuity curve with the simulated average flow values, it can be stated that in order to provide environmental water rights, the flow continuity curve method has a higher performance than the Tenant method.