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Hydrological changes and river regulation in the UK

Higgs, Gary and Petts, Geoffrey E. (1988) Hydrological changes and river regulation in the UK. Regulated Rivers: Research & Management, 2 (3). pp. 349-368. ISSN 0886-9375

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Official URL: http://dx.doi.org/10.1002/rrr.3450020312

Abstract

Water levels of streams and rivers in the United Kingdom have been regulated by weirs for more than one thousand years, but regulation of the flow regime by impoundments began in the latter half on the 19th Century. Organized river flow measurements were not undertaken until 1935, and today the average record length is about 20 years. Only three gauging stations have provided data suitable for pre- and post-impoundment comparisons. Other studies have relied on the comparison of regulated and naturalized discharges. In either case climate and land-use changes make evaluation of the hydrological effect of impoundments problematic. This paper reviews research on hydrological changes due to river regulation in the UK, and presents a case study of the River Severn to evaluate the influence of Clywedog Reservoir on flood magnitude and frequency. Consequent upon dam completion, on average, median flows have been reduced by about 50per cent; mean annual floods have been reduced by about 30per cent; and low flows have been maintained at about 22 per cent higher than the natural Q95 discharge. However, marked differences exist between rivers. The direct effect of reservoir compensation flows and the indirect effect of inter basin transfers for supply have significantly increased minimum flows in most rivers, although in the case of the latter this involves the discharge of treated effluents. In contrast, the effects of impoundments on flood magnitude and frequency is less clear and on the River Severn, at least, changes in flood hydrology during the past two decades are shown to be more related to climate change than to river regulation.

Item Type:Article
Research Community:University of Westminster > Life Sciences, School of
ID Code:5974
Deposited On:11 Feb 2009 12:03
Last Modified:22 Dec 2009 10:26

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