A spatially-distributed cost-effectiveness analysis framework for controlling water pollution

With the aim of comparing various agro-environmental measures to control pesticide pollution in surface waters, we propose a methodological framework for spatially-distributed cost-effectiveness analysis. We use the Soil and Water Assessment Tool (SWAT) model to assess the effectiveness of the measures applied, and we develop an aggregated bio-economic model using the General Algebraic Modelling System (GAMS) to evaluate the costs of their implementation. Finally, we propose a ranking of these measures based on their cost-effectiveness ratios. This approach is applied to the Gers river basin in southwest France. The findings clearly demonstrate that of all the measures we considered, grass strips and mechanical weeding are the most cost-effective in reducing pesticide-related water pollution. On the other hand, measures such as longer rotation sequences and catch crops, although relatively inexpensive to implement, fall short in terms of reducing pesticide pollution. Furthermore, we found that the cost and effectiveness of measures largely depended on where they were implemented, as the framework proposed takes account of physical variables and farm activities scattered within the watershed. Possible uses of this integrated framework as a communication tool in participatory river basin management are also discussed.