OPTAIN project

OPTAIN: OPtimal strategies to retAIN and re-use water and nutrients in small agricultural catchments across different soil-climatic regions in Europe 

Duration : September 2020 and February 2026 
Funding mechanism : Horizon 2020 
Status: Ongoing project (until February 2026) 

OPTAIN is an EU-funded research and innovation project implemented between September 2020 and February 2026 with a budget of almost 7mil €. The project aimed at improving the understanding of potential practical implementation of Natural/Small Water Retention Measures (NSWRMs) in agriculture catchments across Boreal, Continental, and Pannonian biogeographic regions while combining scientific and stakeholder processes. In collaboration with Multi-Actor Reference Groups (MARGs) across 14 European case studies, OPTAIN researchers upgraded and built SWAT+ modelling and optimization tools to identify Natural/Small Water Retention Measures (NSWRMs) suitable for implementation in agricultural catchments. Through this approach, they assessed the potential of NSWRMs to retain water and nutrients while accounting different climate projection scenarios.

• Identify, assess, and compare effective Natural/Small Water Retention Measures (NSWRMs) for retaining and reusing water and nutrients in small agricultural catchments across diverse soil–climatic regions in Europe, including Continental, Pannonian, and Boreal zones.
• Co-design, together with local stakeholders, optimal combinations and spatial allocation of retention measures at farm and catchment scales, balancing environmental performance, economic viability, and climate resilience.
• Develop integrated assessment methods, indicators, and decision-support tools that enable evaluation of trade-offs and synergies between water quantity, water quality, agricultural production, and ecosystem services under current and future climate conditions.
• Translate scientific knowledge into a practical learning environment and policy-relevant guidance to support wider uptake, replication, and mainstreaming of nature-based retention solutions in European water and agricultural policies. 

GWP CEE acted as a key partner in OPTAIN, bridging scientific research and practical implementation through stakeholder engagement, communication, and policy-oriented activities. GWP CEE co-coordinated stakeholder engagement and participatory processes in 14 case studies across Europe, ensuring that farmers, water managers, and authorities were actively involved in the co-design, testing, and evaluation of Natural/Small Water Retention Measures. We contributed to knowledge exchange across regions, supported dissemination and exploitation of project results, and translated scientific outputs into accessible guidance for practitioners and policymakers. Through its regional network, GWP CEE strengthened the uptake, replication, and long-term impact of OPTAIN outcomes beyond the project’s lifetime.

Contact of the responsible GWP CEE project manager: ivana.korn@gwpcee.org

The OPTAIN Learning Environment was developed as a comprehensive platform for knowledge exchange extending beyond the project’s lifetime. It provides structured access to educational materials, practical tools, and evidence-based insights on sustainable water and nutrient management. Designed for farmers, researchers, advisors, and policymakers, the platform supports the dissemination of best practices and innovative solutions across different regional contexts. By combining scientific findings with practical guidance, it helps users better understand nutrient flows, soil-water interactions, and sustainable agricultural practices. The platform also encourages cross-sector collaboration and continuous learning, enabling stakeholders to adapt solutions to local needs.

Water Governance/Impact: The learning environment strengthens knowledge-based decision-making and supports improved nutrient management, reducing water pollution and enhancing ecosystem resilience. It contributes to more sustainable agricultural practices and promotes efficient water use across regions.

Read more about OPTAIN Learning Environment: OPTAIN Learning Environment | ePLANETe Platform