Assessment of adaptation scenarios for agriculture water allocation under climate change impact

The main necessity of sustainable water resource management is an accurate estimation of the water demands. Therefore, all the factors affecting water demand in different sectors should be considered. Based on recent investigations, climate change has impacted the hydrologic system and subsequently the water demands. Thus, this study attempts to identify the potential impacts of climate change on the water resources management scenarios in the future horizons at the Moghan Plain, northwest of Iran. These scenarios will be compared and afterward, their impacts on water demands will be determined. For this purpose, the Water Evaluation and Planning (WEAP) model was employed to simulate the water basin resources system for 2021–2040, 2041–2060, and 2061–2080 future periods. Additionally, nine scenarios for water resources management were developed in the WEAP model by considering the impacts of climate change. The climate change scenarios were based on a combination of different Global Climate Models (GCMs) outputs for the climate change scenarios SSP245 and SSP585. Although all the agricultural water demands of the basin were fully met under the different climate changes scenarios, the external driving forces, i.e., the development of agricultural farms and the supply of environmental flow requirements, and their impacts on the region have shown the necessity of investigating and examining the adaptation scenarios in this region to provide the necessary water resources for agriculture. Furthermore, the maximum increase and decrease of the required water demands respectively were observed in the scenarios of external control, increasing area of the irrigated agriculture by up to 29.4%, and adaptation scenario of upgrading irrigation systems and increasing irrigation efficiency by up to 18.28% on the climate change scenario SSP585. The outcomes of this study will help decision-makers regarding the prioritization of climate change adaptation strategies toward more sustainable water resources management schemes.