Groundwater sustainability for irrigation in the semi-arid Konya Closed Basin, Türkiye, under climate change scenarios

Abstract Numerous aquifer systems are being overexploited to meet the ever-increasing water demands for domestic use, industry, and foremost, agriculture. In this study, the concept of net inflow is explored, combined with groundwater flow modeling to assess the impact of climate change and agricultural practices on the sustainability of groundwater resources. The net inflow concept aims to develop a relation between water level change and groundwater abstraction that can help in the management of groundwater resources. The study is applied to the water-stressed semi-arid Konya Closed Basin (KCB), an agricultural endorheic basin in central Türkiye. A groundwater flow model covering the entire basin, based on the MODFLOW/UZF programs, simulates vertical water flow in the vadose zone and Dupuit flow in the upper aquifer of the underlying subsurface system. The model was calibrated using crop cultivation area, crop water requirements, irrigation efficiency, and groundwater level observations from 29 long-term monitoring wells. Scenario analysis using the calibrated model combined with the net inflow concept and 17 high-resolution climate model projections from the EURO-CORDEX framework were used to examine the sustainability of the basin’s groundwater resources. The scenarios considered different water management and irrigation practices co-developed with local stakeholders. Model results show that with the adoption of enhanced irrigation technologies only, groundwater levels will continue to decrease. By combining improved irrigation efficiency with reverting to traditional rainfed crops, it is shown that the overexploitation of groundwater can be mitigated, enabling the protection and more sustainable use of this critical resource.