River restoration: Paradigms, paradoxes and the urban dimension

River restoration is an increasingly common feature of river and environmental management, and may be characterized by one of several 'restoration paradigms'. These paradigms reflect the key drivers for restoration efforts, and the scientific expertise used to underpin intervention options. At present, however, success rates for restoration schemes are low, and concerns are growing that conventional approaches to river restoration may be fundamentally flawed. Particular issues arise in the case of urban environments, where the case for restoration intervention may otherwise be strongest. In this review, the restoration paradigms are introduced, and the requirement for increased multi-disciplinary perspectives and more comprehensive appraisal processes is outlined. Characteristics of urban rivers are also described. Some paradoxes arising from misclassification and inappropriate conceptualization of these highly fragmented systems are presented, which offer grounds for more optimistic assessments of likely restoration success. Keywords River reconnaissance; river restoration; stream classification; urban rivers