Exploring the interactions between flood defence maintenance works and river habitats: the use of River Habitat Survey data

1. More extensive physical management of rivers in response to increasing flood risk, and action to improve the ecological quality of rivers represent two major, and potentially conflicting, challenges. 2. Improved understanding of the interactions between flood defence works and habitat structure must be achieved in order to satisfy both of these demands in the context of flood risk management and habitat improvement. 3. This paper examines the ‘extensive’ and ‘intensive’ use of data derived from a standardized method of assessing habitat character to explore the effects of flood risk maintenance works on river habitat quality. 4. Analysis of the UK River Habitat Survey (RHS) data set reveals some broad trends towards reduced habitat heterogeneity associated with recent flood defence works such as dredging and weed-cutting. 5. These observations correspond with published localized experimental work and suggest that the RHS database can be a useful resource for identifying relationships at relatively broad scales. 6. Applying the RHS methodology at finer spatial scales for sites experiencing continuing maintenance reveals contrasting results and highlights some key methodological issues; these include the availability and selection of high quality benchmark conditions, the legacy of past management, lag times associated with maintenance and recovery, and recording of marginal habitat features. 7. Small modifications to the RHS method could enable calculation of more detailed habitat indices while maintaining comparability with the national dataset. 8. If the issues identified in this paper can be addressed or accounted for, RHS could be an important tool for assessing the relationship between flood defence management and new statutory obligations for ecological improvement. Copyright © 2009 John Wiley & Sons, Ltd.

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