EVALUATION OF CLIMATE CHANGE IMPACT ON WATER RESOURCES AVAILABILITY (A CASE STUDY ON FINCHAA-AMERTI .. NESHE MULTIPURPOSE CASCADE RESERVOIRS)

Abstract

The subject of changing or fluctuating climate is one of the central issues facing the atmospheric sciences community. The most profound effect of such climatic changes may be major alterations in regional hydrologic cycles and changes in regional water availability. Within a context of increasing water scarcity, climate change threatens to exacerbate the current supply­ demand imbalance. In this study, the impact of climate change on water availability and the reliability of the resources to sufficiently satisfy the increasing demand under changing climate on Finchaa Sub-basin have been modeled and evaluated using the integrated hydrological/water management model, known as WEAP. WEAP has been utilized to simulate future water available in the study area using the runoff generated by the hydrological HBV model as an input. The performances of the models were assessed through calibration and validation and resulted R 2 value which is greater than 0.8 for all the three sub-catchments. The predicted future climate variables showed an increasing trend for both maximum and minimum temperature. However, for the case of precipitation it doesn't manifest a systematic increasing or decreasing trend in the next century. The results showed that the total water availability in the study area is expected to decrease by 11.88% (1 , 670.57 Mm 3) in the next thirteen years. Relative to the base scenario, the simulated future inflow to Finchaa and Neshe have shown an average slight increment at the end of 2025 and a small decrease at the end of 2040. But, the simulated future inflow volume to Amerti reservoir has shown that there is likely a small and considerable decrease at the end of 2025 and 2040 respectively. Considering the future maximum expansion in the study area, all future and existing demand sites in the study area are fully satisfied with 100% demand site coverage and 98.89% demand site reliability under changing climate. Finally it is concluded that, even though the demand in the sub-basin is increasing steadily, the study confirmed that the available water resources is enough to satisfy the increasing demand under changing climate.