It will soon be possible to define areas at risk of transfer of plant protection products (PPP) via runoff waters and percolation using simplified indicators, thus avoiding the pollution of rivers and streams and water tables.
These indicators will help to develop a decision support tool (DST) which, depending on the environmental context of an agricultural parcel, will help users to choose which product to apply, the application date and even take weather conditions into account. This will help to prevent the pollution of surface water or groundwater, which can cause major disruptions in aquatic ecosystems as well as making water unusable in terms of consumption.
To be able to develop such a DST, the first stage consists of simplifying complex PPP transfer models. A great deal of expertise is required to use this type of model and there is also a large amount of input data, which is often unavailable on a regional level. Furthermore, models such as these are dependent on a large amount of computer resources. As for the indicators, they are easier to implement and faster to execute. It is possible to generate qualitative information that can be used as a DST by farming advisers or the farmers themselves.
A connectivity index was therefore developed for surface water and compared with a more complex model (SWAT). The results show that thanks to the connectivity index, it is possible to reliably assess areas at risk of PPP transfer at the level of agricultural watersheds. At the same time, the modified DRASTIC indicator used to discriminate between parcels the most at risk in terms of the underground transfer of PPP in catchment areas, shows similar results to more complex specialised models (GeoPEARL, MetaPEARL).
These indicators were integrated into a DST prototype that allows you to compare different PPP usage scenarios and to guide the user towards the strategy that is most favourable to maintaining the quality of the water resources. Before it is implemented in Wallonia in three years time, future developments of the DST will consist of maximising the validation of the indicators, integrating a greater number of PPP usage scenarios and facilitating the use of the DST to make it more accessible to the largest number of people.
Photo caption: It is necessary to take the environmental context into account during plant protection treatments in agricultural areas to maintain the quality of the water
Photo Sébastien Champion - Naturimages