Groundwater dominated rivers

This paper explores the signi®cance of groundwater dominance in the surface water system through a combination of review and an exposition of the general hydrology, ecology and geomorphology of rivers draining the main UK aquifers. Groundwater dominance is shown to vary according to the nature of the aquifer lithology, the mechanism of groundwater:surface water interaction and the scale at which one examines this interaction. Using data derived from a range of studies including the UK Environment Agency River Habitat Survey and the UK Institute of Freshwater Ecology RIVPACS invertebrate database it is shown that the nature of the aquifer and mode of in ̄uent discharge strongly control the hydrological and ecological characteristics of the environment but that a speci®c groundwater ecology or hydrogeomorphology is masked by the overriding controls exerted by aquifer geology and catchment topography. Despite this, it is clear that river systems dominated by groundwater ̄ows have speci®c hydrological characteristics and management issues that require holistic, multidisciplinary approaches that recognise the signi®cance of groundwater and the nature of the interaction with the surface water environment. Copyright # 1999 John Wiley & Sons, Ltd.