Trends and purposes of European river monitoring and restoration

Abstract

This study provides the first geospatial analysis of the trends and uptake of European river monitoring and restoration. European monitoring targets rivers draining agricultural and urban land, which leads to geospatial biases due to the co-occurrence with soils, topography, and river orders. Most notably, intermittent rivers and ephemeral streams are underrepresented due to lower monitoring intensities in Southern Europe, headwaters, and catchments with steeper slopes or less arable soils. Improving monitoring efforts in these ecosystems can advance our scientific understanding of complex linkages between ecological quality outcomes and specific stressors. Large differences were found in the spatial coverage of river monitoring and chemical status reporting between European river regions, which highlights comparability issues with the outcomes of Water Framework Directive river quality status due to the ’one-out-all-out’ principle. Chemical status monitoring is also less frequent in agricultural catchments, which leads to a knowledge gap on the impacts of priority substances, such as pesticides, on agricultural rivers. These uncertainties around the actual quality of rivers are propagated to the prioritisation, design and purposes of river restoration. River restoration coverage is distinctively higher in Western Europe and larger urban rivers, compared to lower incidences in headwaters draining agricultural or (semi-)natural catchments. Across most regions and geospatial factors, biodiversity conservation was the major purpose for river restoration. Agricultural headwaters and intermittent rivers are low-hanging fruits for future river restoration, wherein socio-economic drivers of river restoration can be leveraged to achieve parallel goals of biodiversity and water resource management.