Achieving the good status objective for groundwater bodies affected by diffuse agricultural pollution: where and how to act to be cost-effective?

Abstract

In France, more than 40% of groundwater bodies are affected by diffuse agricultural pollution. The Water Framework Directive requires to implement cost-effective action programs in order to achieve the good status objective by 2027 at the latest. However, the selection and design of cost-effective action programs raises several methodological issues. This paper proposes a new framework to implement a cost-effectiveness analysis that links results from participative methods and modelling by integrating economic, agronomic and hydrogeological approaches. The approach is applied here to a groundwater body located in the Ain alluvial plain in France. We show that implementing longer crop rotations on the South-East part of the groundwater body would be sufficient to reach good status. The results also highlight the uncertainties related to the evolution of groundwater quality, show that current agri-environment schemes are insufficiently attractive, and may be inappropriate to achieve good status of the water body by 2027.