The catchment approach as the scientific basis of river basin management

Abstract

Human impacts on river systems worldwide create a compelling case for effective river basin management. This paper examines the strengths and weaknesses of this approach and the role of science in underpinning it. There are many practical reasons for adopting integrated catchment management (ICM): achieving sustainable use of water resources demands a catchment approach to problems of water quality and quantity. Together with philosophical and economic arguments for nature conservation, and the legislative requirements laid down in the EC Water Framework Directive (WFD), the need for ICM is undeniable. In practice, however, ICM is hindered by significant gaps in scientific understanding. Some are geographical (e.g. inadequate knowledge of headwaters), some ecological (e.g. links between catchment processes, habitats, and aquatic species) while some relate to scale (e.g. extrapolating small-scale observations to entire catchments). The WFD is playing an increasing role in European river basin management, yet technical tasks such as defining 'reference conditions' or classifying 'ecological status' are hampered by inadequate scientific knowledge. It is essential that the results of scientific studies are made widely available, both through peer-reviewed publications and by conversion into practical guidelines or manuals for river engineers and managers. Although the river basin is a logical and defensible unit for conservation and management, the paper concludes that an even wider perspective is needed. Supra-catchment pressures from acid deposition or invasive alien species pose serious threats to rivers: efforts to tackle these issues cannot be confined to catchment units but must look out beyond the watershed.