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.
Project objectives :
- 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.
Role of GWP CEE in the project:
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
Link to the official project website: Optain | Optimal Strategies to Retain Water and Nutrients