Implications of natural soil piping for basin management in upland Britain

Natural soil pipes are a common feature in the British upland landscape, especially in podzolic and peat soils (spodosols and histosols). It is estimated that 30% of Britain (UK) is covered by soils susceptible to pipe development. Current reevaluation of the use of the uplands, including moves to preserve biodiversity, rehabilitate acidified surface waters, afforest, and recreate a 'pre-industrial' landscape with aesthetic planting of previously native trees and shrubs, highlights the need to understand the key processes of hillslope hydrology that may affect the impact of any policy changes and the effectiveness of any rehabilitation programme. This paper reviews the evidence that soil piping can have a significant effect upon streamflow response, water quality and acidification, as well as creating diversity in plant communities and soil types, and initiating erosion features. Evidence from the University of Wales Experimental Catchment at Maesnant is compared with the results of observations elsewhere in the British uplands and with experience gained from research programmes in other countries. Some of the effects of piping, such as aggravation of the effects of acid rain and increases in the rate of floodflow response, may currently be regarded as negative. Conversely, its effects on landscape diversity are clearly positive. Piping is a natural process and should be regarded as an integral element in preserving and restoring a 'natural' landscape. Most importantly, the presence of piping can alter the 'stormflow contributing area' within a basin and significantly expand the area of catchment over which landuse change is likely to impact upon the hydrological and hydrochemical response of the catchment. The paper analyses the environmental impact of piping and considers the implications for basin management. Copyright (C) 2004 John Wiley Sons, Ltd.