Quantifying Crop Responses to Brackish Water Use Across the Mediterranean with Minimal Input Modelling

Water scarcity is tightening its grip on global agriculture as climate change advances, with the Mediterranean facing particular strain. About thirty percent of its 11.32 million hectares of irrigated land overlies saline aquifers, forcing farmers to depend on water of declining quality. Brackish water represents a viable substitute for freshwater, yet its adoption remains limited because current tools for assessing crop specific impacts often require detailed field measurements that are rarely available at regional scale. This study presents a simplified agro hydrological modelling framework designed for first level analysis of salinity effects on crops, soil, and irrigation demand. It operates with a small collection of standard inputs, including climate, soil properties, and irrigation water salinity, allowing consistent application across large areas. The framework is applied to twenty four crops across the Mediterranean under four irrigation strategies: freshwater baseline, brackish water only, brackish water with leaching, and mixed irrigation adjusted to maintain soil salinity at half of each crop’s tolerance level. Across regions influenced by saline aquifers, the leaching based strategy cuts freshwater use by seventy six percent compared with the freshwater baseline, while still maintaining soil salinity within acceptable crop thresholds. At the basin scale, mixed irrigation shows a total water demand of 33.68 cubic kilometres per year with limited salinity stress, providing an effective balance between freshwater conservation and soil protection. Field-level simulations for the Zelba area in Tunisia, using brackish water of 7.2 dS per metre for wheat, barley, and sorghum, confirm the strong performance of management strategies that pair brackish water with targeted leaching. This scalable approach provides rapid and reliable insight into the feasibility of brackish water use, helping farmers and policymakers evaluate irrigation options, protect soil quality, and plan freshwater savings in water-scarce environments.