A Multi-Objective Decision Support Tool for Rural Basin Management

Irrigation and fertilization of crops are common practices necessary for the viability of agricultural communities, but also responsible for water scarcity and water quality deterioration. The effort to cost-effectively manage fresh water availability and diffuse nutrient pollution at the same time needs to take into account trade-offs between economic and multiple environmental objectives. Agricultural Best Management Practices (BMPs) are adaptation options for mitigating both environmental problems; however, their optimal allocation across the landscape becomes a multi-objective problem, with the need to identify the most suitable combinations. An efficient Decision Support Tool developed in MATLAB, able to assess the cost-effectiveness of irrigation and nutrient application management BMPs in reducing agricultural water use or nutrient losses to surface waters is used in this study. The tool integrates the process-based Soil and Water Assessment Tool (SWAT) model, which evaluates the effectiveness of the BMPs at different catchment locations, into a multi-objective genetic algorithm, which optimizes their selection and placement across the agricultural land. The novel software aspect of the tool is the automatic development of a BMP database (a look-up table), which stores environmental data and costs for the different locations and BMPs implemented on them and is used in the optimization scheme instead of the computationally intensive model. The application of the tool with the purpose to minimize cost, irrigation water consumption and nitrate-nitrogen loads to rivers from the cotton fields of the Pinios River Basin, the largest and most intensively cultivated area of Greece, demonstrated specific BMPs allocation schemes that could be affordable-cost solutions of efficient water quantity and quality management. In this paper, one such solution is presented and discussed, demonstrating the potential usefulness of the methodology in identifying costeffective management interventions, even in large, complex river basins and under a climatically and socio-economically changing environment.