Participative modelling to help collective decision-making in water allocation and nitrogen pollution: application to the case of the Aveyron-Lere Basin

The aim of this study is to develop simplified tools and methods in collaboration with local stakeholders to facilitate collective decision-making. The project is based on a series of experiments carried out between farmers and environmental officers and researchers (Aquae Project)1 on the Aveyron-Lere catchment area. Within this framework, a model of the catchment area was constructed to examine water consumption and nitrate losses in the area, and scenarios were simulated to assess acceptable solutions. Two types of scenarios were tested with the objective of respecting water allocation and reducing nitrate losses: 1. irrigation and fertilisation optimisation; 2. crop rotation management at the level of five areas in the catchment area as well as at whole basin level. The model allows farmers to assess the cost of various management scenarios of respecting the norms set according to inter-annual climatic variability.