Evaluation of the effectiveness of natural water retention measures : support to the EU blueprint to safeguard Europe's waters

In the context of the impact assessment for the policy document "Blueprint to safeguard Europe's waters", the European Commission has developed a common baseline scenario bringing together climate, land use and socio-economic scenarios and looking at the implications for water resources availability and use under different policy scenarios. This study was carried out by the Joint Research Centre of the European Commission with the support of Stella Consulting SPRL, Brussels. It shows the impact of no-regret natural water retention measures on water quantity which can, in turn, be used to quantify ecosystem services related to water provision, water flow regulation and the moderation of extreme flows. It also contributes to the identification of multifunctional adaptation measures that reduce the vulnerability of water resources and related ecosystem services to climate change and other anthropogenic pressures. Within the context of this report "no-regret" is solely based on hydrological impact. The additional report "A multi-criteria optimisation of scenarios for the protection of water resources in Europe" (EUR25552) addresses co-benefits and costs. The novelty of this study is in linking climate, land use and hydrological scenarios and models on a pan European scale and providing a first quantitative pan-European overview of the effects of 'green' measures on discharge. This should encourage Member States to further explore the use of efficiency measures and foster communication between stakeholders. 12 different policy scenarios were used, addressing changes in forest and urban areas, agriculture practice, and water retention. Locally some of these scenarios were estimated to change low flows and flood discharge up to 20%. For the 21 defined macro-regions in Europe there is a clear difference in the impacts of measures and for each region the effectiveness of each scenario has been ranked in terms of increasing low flow or reducing flood peaks.