Hydro-climatic and land use changes in the River Lune catchment, north west England, implications for catchment management.

Orr, Harriet and Carling, P.A. (2006) Hydro-climatic and land use changes in the River Lune catchment, north west England, implications for catchment management. River Research and Applications, 22 (2). pp. 239-255. ISSN 1535-1459

Abstract

Reported trends across the British Isles, illustrate changing rainfall gradients. Northern areas have become wetter in recent decades with greater variation between NW and SE rainfall totals. This paper explores hydro-climatic changes in North-West England over the last 140 years as part of a whole catchment investigation into the nature and causes of change in fluvial geomorphology. Variability in runoff in the Lune catchment is explained in terms of observed climate and land use changes; implications for river and catchment management are discussed. Area average annual rainfall in the North-West of England show no clear trend over the last 100 years although rain gauges at higher altitudes appear to show increased totals. Over the last 30 years changes in the seasonality of rainfall have been observed. A greater proportion of annual rainfall has occurred in the winter half-year and an increased frequency of wet-days has been linked to catchment-scale flooding. More rain falling on upland areas (>300m) has resulted in more rapid runoff from these areas enhanced by land use practices � specifically in heavily grazed hills with a short vegetation cover. The result is a highly varied runoff response within the catchment with localised increases in stream power and the potential for geomorphic change. This effect is �damped� lower down the catchment highlighting the importance of within catchment variability and the need to conduct hydrological analysis at smaller than whole catchment scales. These findings have important implications for water resources, in particular: water storage within catchments; changes in the duration and frequency of floods and droughts; mobilisation of sediment; erosion; channel and flood risk management; and ecological function.