The Petite Glâne catchment, located in the western Swiss Plateau within the Cantons of Fribourg and Vaud, is one of the OPTAIN project case studies. This region is characterized by its diverse agricultural activities and unique environmental challenges, making it an ideal case study for implementing and assessing Natural/Small Water Retention Measures (NSWRMs).
Background
The Swiss Case Study focuses on the Petite Glâne catchment, an area known for being highly suitable for arable farming: nearly three quarters of its area consists of pastures and cropland. The upper zone of the catchment has rolling hills, and the Petite Glâne stream remained semi-natural and lined with forest. In contrast, the lower part of the catchment is part of the Broye plain, which is flat, with intensive agriculture, and a channelized and straightened stream.
The primary agricultural activities in this region include crop cultivation and livestock farming. Farmers are growing various crops suited to the temperate climate such as corn, wheat, rapeseed, sugar beet and potatoes.
Environmental challenges
Although the soil and climate are highly suitable for arable farming, the region is increasingly experiencing water shortages during summer. There is often not enough water in the Petite Glâne and the bigger Broye river for irrigation. In addition, extreme events with heavy rainfall are increasing in frequency and intensity. These challenges impact both the environment and agricultural productivity and will further aggravate with climate change.
These changes pose significant risks to the sustainability of agricultural practices in the region. Against this background, OPTAIN explores efficient land use and land management strategies as well as technical measures that increase the capacity of soils to absorb and store water while improving nutrient retention and decomposition. These natural and small water retention measures (NSWRMs) are discussed and evaluated jointly with a Multi-Actor Reference Group (MARG).
Figure 1: Water retention problems in the Petite Glâne catchment: waterlogging in 2021 (left) and dry period in 2022 (right)
Stakeholder Engagement
Figure 2: Workshops with local stakeholders in 2021 (left) and 2022 (right) in Avenches, Switzerland.
Active involvement of the MARG with local stakeholders is a cornerstone of the OPTAIN project in the Petite Glâne catchment. Farmers, authorities from the agricultural and environmental sector, environmental organizations, and researchers are integrated into the decision-making process. The project also collaborates with the Centre for Agricultural Advisory and Extension Services, AGRIDEA, to enhance stakeholder engagement and knowledge transfer
NSWRMs
As in all 14 OPTAIN case studies, in the Swiss case study, the project employs a harmonized approach to select, document and model Natural Small Water Retention Measures (NSWRM) including the MARG.
First results indicate that the measures impact both water quantity as well as quality. For the water balance, the NSWRM low tillage combined with cover crops has the most significant impact: it retains the water in the catchment area, reducing the maximum stream flow and increasing percolation and soil water. Low-tillage with cover crops also significantly reduces the average sediment loss from the agricultural fields. Similarly, though at a lesser extent, the NSWRM slope subdivision with grass seam also shows high potential in reducing sediment loss. Furthermore, riparian buffers are crucial in holding back sediments and nutrients, thereby reducing sediment and nutrient loads in water.
Figure 3: First results of modeling the impacts of selected NSWRMs on water balance as well as nutrients and sediments.
For Petite Glâne, this structured approach ensures that the following selected NSWRM are locally relevant, well-documented, and integrated into broader water retention strategies within the OPTAIN framework.
Conclusions
The efforts in the Petite Glâne catchment underscore the significance of integrating agricultural practices with environmental conservation through the implementation of NSWRMs. By addressing nutrient runoff and preparing for climate change impacts, these measures aim to enhance water quality, support biodiversity, and promote sustainable agriculture. The collaborative approach adopted in this case study serves as a model for similar initiatives in other regions, highlighting the importance of stakeholder engagement and tailored solutions in achieving environmental and agricultural sustainability.
Authors: Joana Eichenberger and Tatenda Lemann