Economic evaluation of small desalination plants from brackish aquifers. Application to Campo de Cartagena (SE Spain)

The Campo de Cartagena (Eastern Spain) is one of Europe’s driest areas with a mean precipitation of around 300 mm. One of the main challengesin the region is to secure a reliable water supply in both quantity and quality terms, to provide a water supply and agricultural irrigation, while water desalination has become an extensively applied solution, and one of the most sustainable solutions to the water scarcity problem. As water availability is lacking and groundwater quality is poor, the agricultural sector in Campo de Cartagena has developed small private brackish groundwater desalination plants (15-20 m3/h) through already existing agricultural wells. Costs and benefits (C-B) for citrus cultivation (1 ha) in three such plants have been assessed. The results indicate that for the studied cases, current agricultural management is feasible and costs outweigh benefits, with a positive NPV and a cost/benefit ratio higher than 1. The internal rate of return is also positive and higher than 11%. The results evidence practical and theoretical implications as to how to increase water resources in areas where water is scarce by closing the loop, ensuring farmers’ profitability and encouraging private sector investments.