Implementation of water balances in the EU : final report

A water balance is - in simplified terms - a calculation of the water quantity available during a specific time period (such as a month or a year) in a river basin, considering water abstraction, use and consumption. This calculation can be used to maintain sufficient water levels in water bodies, to ensure their good status/potential, to allocate water to the different users, to avoid overexploitation of natural water resources, and to build resilience against climate change. In some EU Member States, water balances have been in place for a long time, whilst for others this is a new field of water management. To support their development and use, an EU guidance document was adopted in 20151; however, there are still major challenges for their implementation. The analysis for this report has grouped these challenges (including on the basis of Member State self-assessments) in four blocks: - Data availability: Though most EU Member States implement water balances, usually at the river basin level, water quantity measurements that can help determine consumptive uses across sectors are often either not available or not undertaken systematically. - Data reliability remains a challenge for many Member States, in particular regarding the metering or estimation of water use and consumption2, especially in irrigation agriculture. A key gap is the estimation of illegal water uses, which in some locations are very significant: these are usually not considered in water balances. Avoiding double accounting for reused water and groundwater-surface water interactions is a challenge in several Member States. - Usability of water balances for river basin management is a further issue. Often the water balances are developed only by water managers without involving relevant researchers and other interested parties and do not necessarily reflect indicators such as sustainability thresholds which can directly be incorporated into the RBMPs and management decisions. - Harmonisation of water balances across borders remains a major challenge, often due to a lack of mutually accepted data, common definitions and procedures for preparing water balances. This report presents, for many (but not all) of these challenges, illustrative examples that have been collected from volunteering Member States. These examples could guide others that are still in the process of setting up water balances or struggling with implementation challenges.