Mapping runoff risk for plant protection products in a steep alpine vineyard: A parcel-scale GIS approach in Yvorne (Switzerland)

Abstract

In the face of environmental challenges and economic constraints, the transition to sustainable viticulture has become both a necessity and a strategic lever for winegrowing regions. In this context, the Yvorne Grandeur Nature association, founded in 2019, aims to make Yvorne (Switzerland) the first Swiss appellation fully committed to sustainability across the entire value chain, from grape production to wine marketing. The appellation is conceived as an open-air laboratory for testing and promoting more environmentally friendly practices, with a methodology designed to be transferable to other winegrowing regions.

Yvorne is located on the south-facing slopes of the Vaud Alps. Most of the vineyard is established on an alluvial fan formed after a major landslide from the massif north of the village. The lower plots have slopes of around 10°, whereas those in the upper part reach up to 58°. The village is crossed by a river, which subsequently flows into the Rhône. The combination of steep slopes and the presence of this watercourse increase the risk of plant protection products (PPPs) being transported to surface waters.

In 2024, a parcel-scale analysis was carried out to identify areas vulnerable to PPPs transfer via runoff. The approach combines field surveys with spatial analyses performed in a geographic information system (GIS). The study area covered 150 ha, corresponding to the entire vineyard surface of Yvorne. The variables considered include slope gradient and length, distance to the hydrographic network, landscape elements influencing runoff (road surfacing, drainage systems, hedges, forests, grass strips), soil texture, land use (proportion of grass cover within plots) and orientation of tillage in relation to the slope. Each factor is classified into different risk levels (from none to very high) and assigned a coefficient ranging from 0 to 4, defined on the basis of bibliographic references and expert knowledge (Noll et al., 2010). A multi-criteria evaluation grid is then used to integrate these factors and compute an overall risk index for each plot. This methodology allows to generate thematic maps for each factor and a synthetic map of PPPs transfer potential.

The analysis of each surveyed factors is ongoing and results are expected in spring 2026. This work will provide winegrowers with an operational decision-making tool, enabling them to identify at-risk plots and adapt their practices by implementing tailored corrective measures (e.g. grass cover management, tillage practices, landscape features) to reduce the transfer of plant protection products to surface waters.

References

Noll, D.; Dakhel, N., & Burgos, S. (2010). Appréciation des risques de transfert de pesticides par écoulement de surface.  Swiss Agricultural Research, 1(3), 110‑117. https://www.agrarforschungschweiz.ch/en/