Physical habitat, eco-hydraulics and river design: a review and re-evaluation of some popular concepts and methods

摘要: 1. Improved linkage between physical characteristics of rivers and biological performance or potential is a recurrent theme in contemporary river survey, management design. This paper examines the degree to which flow biotopes functional habitats may be differentiated with respect habitat delimiters, i.e. depth, velocity Froude number. 2. Re-examination published data demonstrates only very broad associations biotopes, low, medium high bands chosen delimiter. The are also not consistent different delimiters. 3. Re-analysis complicated by considerations research design methodology. Further studies required greater control on circumstances observation (particularly stage seasonality), explicitly for variance within cases, adopt more terminology. 4. Field single reach at low flows indicate that use number, particular, requires careful interpretation. Very depth combinations can exhibit similar numbers. obscure important contrasts, such as those channel margin centreline environments. 5. reveal even basic (riffle pool) units morphology strong stage-dependence. There significant variations when margins isolated from definitions bedforms analysis data. Current practice seeks simplify field survey cross-section transects therefore likely misleading. 6. Given these difficulties, attempts link ecological response appear premature. might, however, directed identifying possible types habitats. In this sense, biotope concept profitably employed one several surrogate measures biodiversity.