Ecological quality assessment of rivers and integrated catchment management in England and Wales

摘要

This paper deals with the ecological assessment of river quality and its relationship to integrated catchment management. The concept of catchment or river basin management has been a basic management tool in England and Wales since 1990; it is now being enshrined in the Water Framework Directive. Historically the statutory and operational drivers in the UK have lead to the development of distinctly different approaches to the management of water quality, water resources (quantity) and physical river structure. More recently a proactive approach to the sustainable use of water promulgated in the Local Environment Agency Plans has also dealt with the three management aspects in some isolation although greater effort has been made to present the issues in an integrated manner. The Water Framework Directive calls for further integration in river basin plans and associated programmes of measures. In the paper the three approaches are described and considered in light of the requirements of the Water Framework Directive. Water Quality classification and objective setting has been based on information from the survey of benthic macro-invertebrates. The Biological Monitoring Working Party Score and the predictive software River Invertebrate Prediction and Classification System (RIVPACS) have been used to set site-specific targets for management purposes. RIVPACS includes a reference database of minimally impacted sites for comparison with the observed data. This approach is in line with the requirements of the directive. Physical river structure work has been based on monitoring of in-river and river corridor characteristics. The River Habitat System (RHS) has also developed a reference database but is less well developed in terms of its predictive ability. The use of ecological information in Water Resource management has taken a different approach based on the concept of differential ecological sensitivity to the hydrological regime within the river. In order to develop a truly integrated approach to catchment management the importance of each the three aspects of management on the biological community will need to be prioritised. It will also be necessary to give careful consideration to the inter-actions between quality, quantity and structure.