Department Systems Analysis, Integrated Assessment and Modelling

Herbicides are chemicals substances used in modern agriculture to reduce the development of unwanted vegetation. These substances, through various flow pathways, may reach underground waters, streams, and lakes. The presence of herbicides in these water bodies may lead to ecosystem dysfunction, loss of biodiversity, and human water security threats. A better understanding of the factors that control herbicides transport in the natural environment is critical to the development of efficient mitigation measures.

In this project, we will combine multi-model approaches and novel uncertainty estimation techniques to model herbicide transport in two headwater catchments in the Swiss plateau. These catchments have been the location of unique experiments where herbicides application and release have been measured at high spatiotemporal resolution. The expected outcomes of this project consist of (1) a better understanding of the contribution of experimental data in informing the modelling process of diffuse pollution from small agricultural catchments, (2) an improved understanding of the dominant controls on herbicide transport and of appropriate conceptualizations of catchment scale processes and (3) an assessment of the uncertainties associated to the prediction of herbicide concentrations in streams.

The occurrence of herbicides in surface and ground waters is a problem of great environmental concern. The effectiveness of mitigation and remediation measures rely on a better understanding of how the physical processes that control herbicide transport depend on agricultural practices or landscape characteristics. Although our intent is not to develop formal approaches to mitigate risk, our analysis is expected to improve the system knowledge which forms the basis to apply such techniques.