OPTAIN – Optimal strategies to retain and reuse water and nutrients in small agricultural catchments

A major factor limiting crop production in Europe is water stress, which climate change is expected to exacerbate. Projections suggest that many European regions will experience more frequent extreme weather events, such as droughts and heavy rainfall.

Mitigating conflicts between water uses

Natural small water retention measures can help mitigate conflicts between agricultural water uses – e.g. plant production, animals – and other human and environmental demands for water, including drinking water or maintaining environmental flow.

Despite a comprehensive set of techniques available to increase water retention at both catchment and farm levels, knowledge is still lacking on the effectiveness of different measures across various soil-climatic regions and agricultural systems, especially under changing climate conditions.

Identifying promising underutilized water management practices

The general goal of the EU-funded OPTAIN project is to identify most efficient and easy-to-implement techniques for the retention and reuse of water and nutrients in small agricultural catchments. The project focuses on promising and underutilized water management practices.

Providing new insights and creating win-win situations

In close cooperation with local actors, OPTAIN aims to advance the knowledge on natural small water retention measures. It focuses in particular on their optimal spatial allocation, their environmental and economic sustainability, and their socio-cultural impacts. This will provide new insights on how different management practices are best combined with each other and enable the analysis of multiple benefits, win-win situations, and trade-offs, for the benefit of humans and ecosystems.

 The project aims to:

• improve understanding of how natural small water retention within different climatic zones can contribute to water-use efficiency at the farm level;
• identify tools and techniques for stream nutrient recovery and reuse of water at the scale of the agricultural catchment; and
• identify economically sustainable technologies for dry- and wet-spell water management at the farm and catchment levels.

The project will focus on 14 case studies across the Continental, Pannonian, and Boreal biogeographical regions of Europe.

The Swiss case study

CDE leads the Swiss case study in Broye catchment, which straddles the cantons of Fribourg and Vaud. While the soil and climate of Broye catchment are highly suitable for arable production, the area is experiencing a water shortage. With water availability from the Broye or Petit Glâne streams often insufficient, farmers are considering other ways to mitigate increasing drought events – such as an irrigation project to abstract water from Lake Neuchâtel.

As not all arable areas in the catchment are well connected to irrigation infrastructure, natural small water retention measures could provide a key to mitigating drought stresses in future.

Work package on measures and indicators

CDE also leads OPTAIN’s work package on measures and indicators, whose objectives are to:

• identify existing and underutilized natural small water retention measures for stream nutrient recovery and reuse of water, together with all relevant national and local actors for all case study sites;
• assess the ecological, socio-economic, and socio-cultural impacts of these water retention measures, which can be a barrier or an incentive to implementation;
• set up a coherent catalogue of retention measures and select the most suitable options, using WOCAT;
• develop a set of baseline indicators for monitoring and modelling the impacts of natural small water retention measures;
• develop a set of guidelines for measure-specific parameters and scenarios for further investigation at case study level.