Integration of ecological aspects in flood protection strategies: defining an ecological minimum

Abstract

Policy makers are confronted with the question of how to combine sustainable flood protection and floodplain rehabilitation in the best possible way. Both topics deal with spatial planning aspects in a range of scales. This question was the starting point for the development of an evaluation method within the IRMA/SPONGE project Intermeuse, illustrated on the basis of assumed flood protection strategies in the Meuse river basin (the 'sponge' strategy, the 'retention' strategy, and the 'floodplain lowering' or 'winter bed' strategy). The integration of flood protection and floodplain rehabilitation can be performed on two scale levels that are interrelated: on the regional level the focus is on (large parts of) an entire stream basin; on the local level specific site conditions are taken as starting point. Ecological aspects under study are spatial cohesion of habitats as identified by species population persistence modelling (regional, longitudinal level) and required habitat quality for carabid beetles and for meadow vegetation gradients as assessed by correspondence analysis (local, transversal level). The carabid beetles are taken as indicative for the ecological integrity of the river bed, the meadow vegetation for that of the floodplain.A unifying concept in the evaluation of ecological integrity is the ecological minimum: the critical boundary or minimum level of habitat conditions for a potentially good ecological functioning. It is the least acceptable state for a river ecosystem that is still functional to some extent, compared to a natural river ecosystem. The results of this study show clearly that there is a good chance to combine floodplain rehabilitation aims with flood protection activities, both on a local and on an international scale. Although ecological effect assessment and ecological optimizing (referring to a natural reference state) remain basic, additionally the assessment of the ecological minimum helps to define design strategies for integrated flood protection, especially in situations where there is an opportunity for river rehabilitation.

Carabid species responses to hybrid poplar plantations in floodplains in France

“…Increasing anthropogenic activities in these areas however disturb this situation (Ward et al, 1999). Some of these activities target the protection of people and goods from flooding, through bank consolidation and regulation of rivers (Décamps, 1993;Décamps et al, 1988;Geilen et al, 2004). Other human activities concern the use of floodplain resources, such as extraction of gravel, sand or clay, as well as agricultural practices that take advantage of these highly productive lands (Rouquette et al, 2009).…”

Multifunctional floodplain management and biodiversity effects: a knowledge synthesis for six European countries

“…Floodplains are often characterized by a mosaic of habitats differing in age, humidity, sediment properties, productivity, and diversity, abundance, composition and succession state of biota (Geilen et al 2004). This habitat mosaic is inhabited by a multiplicity of generalist and specialist species, both terrestrial and aquatic, which often depend on the relative habitat quality and on proximity and functional connectivity of various habitat patches (Romanowski et al 2005;Scholz et al 2012).…”

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

“…Vis et al, 2001;Van Asselt et al, 2001;Geilen et al, 2004). It was found that none of the newly developed strategies is superior in all respects, and/or to all parties involved.…”