Human freshwater appropriation in Europe: patterns and resilience prospects

Water appropriation for human use can have significant impacts on the functioning of freshwater ecosystems. Reducing water appropriation can be a first step towards increasing water resilience and adapting to climate change, and it is therefore important to understand its spatial and sectorial distribution. In this contribution, we analyze the level of water appropriation in European watersheds, using available estimates of water demand and water availability.

We map an indicator of the level of appropriation of blue water in European river basins by broad water-using sectors, namely irrigation, livestock breeding, public (domestic) supply, the industry and thermal power plant cooling for energy generation. Water demand in a river basin may often represent 10-50% of renewable water availability and, in some regions, it may even exceed 100%, implying that either non-renewable water or transfers of water among river basins are needed.

The analysis shows that the level of water appropriation varies significantly across Europe, generally with a north-south gradient as expected, obviously reflecting the interplay between demand and availability. There is also a significant variability in the patterns of potential appropriation among sectors. In general terms, irrigation, systematically occurring in highly appropriated river basins, tends to be the main driver of water appropriation. Livestock demand is quantitatively less relevant at European scale, but occurs in relatively highly appropriated river basins as well. Energy represents the second most significant driver of appropriation, but tends to occur in less appropriated river basins. Most regions in central Europe show relatively uniform mixes of water demand, with no single sector taking the lion’s share of water appropriation, whereas the dominance of certain sectors, generally energy or irrigation, emerges in many northern as well as southern regions. The trend in water availability that can be anticipated on the basis of available climate projections will exacerbate the current situation particularly for irrigation and livestock.

Based on estimated volumes of domestic wastewater that can be reused for agricultural irrigation, we show how water reuse may substantially help reduce water appropriation in Europe. In general, we show that there is a widespread potential for reuse of water across sectors, that could be further analysed taking into account also other factors (particularly on water quality). Reducing water appropriation by water reuse after achieving efficient water use through appropriate management (“efficiency first”) may contribute substantially to water resilience.