Evaluation of current inland desalination of moderately saline brackish groundwater for expansion of irrigated agriculture

Irrigated agriculture faces significant challenges due to global freshwater scarcity, impacting sustainability and food security. This has increased pressure on groundwater extraction in inland areas to meet the growing demand for irrigation water. This, combined with increasing risk for groundwater salinization, has made desalination of moderately saline brackish groundwater (i.e., total dissolved solids from 3000 to 10,000 mg/L) a key water source for agriculture. However, the high cost of current inland desalination systems may impact crop profitability and their sustainability for agricultural use. This review proposes approaches for developing cost-effective inland desalination systems using moderately saline brackish groundwater, highlights current challenges, and identifies research gaps. This has been achieved through studying three main areas: i) identifying crops that have lower susceptibility to risks associated with the desalinated water cost; ii) evaluating viability of current commercial desalination technologies based on water cost and crop requirements for irrigation; and iii) assessing brine management methods as this could significantly impact its feasibility. Focusing on high-value crops, particularly greenhouse vegetables, and advanced technologies to enhance water-use efficiency is crucial for agriculture using desalinated water. Brackish water RO with recovery rate ≤40 % and shallow-well brine injection, despite restrictions due to current regulations, is a potential opportunity for cost-effective inland desalination. Future research should address critical aspects such as optimal operational conditions and impacts on groundwater aquifers for effective implementation of the system. Alternatively, a High Recovery RO system (i.e., 95 % recovery rate) can make evaporation ponds a potentially cost-effective option for inland desalination.