Towards sustainable flood risk management in the Rhine and Meuse river basins: synopsis of the findings of IRMA‐SPONGE

TLDR

Recent floods in western Europe highlight the need for better flood risk management along the Rhine and Meuse rivers. IRMA‑SPONGE aimed to develop methods and tools to evaluate flood‑risk reduction measures and land‑use/climate scenarios for spatial planning in the Rhine and Meuse basins. The programme comprised 13 projects and involved more than 30 organizations from six countries. Participants concluded that flood risk is rising from climate change and development, upstream retention can reduce small‑basin floods but not large downstream events, and the most sustainable mitigation comes from reducing vulnerability through land‑use and spatial planning while also improving ecological quality of rivers and floodplains.

Abstract

Recent flood events in western Europe have shown the need for improved flood risk management along the Rhine and Meuse rivers. In response, the IRMA-SPONGE research programme was established, consisting of 13 research projects, in which over 30 organizations from six countries co-operated. The aim of IRMA-SPONGE was the development of methods and tools to assess the impact of flood risk reduction measures and of land-use and climate change scenarios, in order to support the spatial planning process for the Rhine and Meuse River Basins. Several important conclusions were agreed upon by participants in the programme; they emphasize the role of spatial planning, especially in areas at risk of flooding, as an important component of flood risk management: 1 Flood risk, defined as a function of both flood probability and potential damage, is increasing not only due to climate change (likely to cause an increase in the probability of extreme discharges) but also due to continued investment in areas at risk of flooding (resulting in an increase in potential damage). 2 Water retention areas and land-use adaptations far upstream may be useful in lowering the frequency of floods in small basins. However, extreme floods far downstream in the lower Rhine and Meuse basins, where the probability of design discharges is less than 1/200 per year, cannot be prevented by such upstream measures. 3 The most effective and sustainable reduction of flood risks could be achieved by reducing the potential damage (vulnerability) in flood-prone areas through adapted land use and spatial planning. 4 Flood risk management organizations should not only aim at a reduction of flood risk but should also seek to enhance the ecological quality of rivers and floodplains.