Hydrometric Register and Statistics-1991-95
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th HydrometricRegister and Statistics-1991-95 INSTITUTE OF HYDROLOGY • BRITISH GEOLOGICAL SURVEY á HYDROLOGICAL DATA UNITED KINGDOM HYDROMETRIC REGISTER AND STATISTICS 1991-95 © 1998 Natural Environment Research Council Published by the Institute of Hydrology, Wallingford; Oxo-ri.OXIO 8BB The Institute of Hydrology forms part of the Centre for Ecology and Hydrology which, like the British Geological Survey, is a componcnt body of the Natural Environment Research Council. ISBN 0 948540 84 2 Editors: Tcrry Marsh and Martin Lees Assistant Editor: Samantha Grccn The acquisition, archiving and validation of the bulk of the river flow data featured in this publication is undertaken as part of the National Water Archive project at the Institute of Hydrology. Martin Lees is the project manager and liaison with the mcasuring authorities (see page 7) is undertaken by a team of regional representatives. In addition to the editorial staff, this team currently includes: Jackie Can, Julia Dixon, Henry Gunston and Felicity Sanderson. •he style and contents of the Hydromctric Register and Statistics 1991-95 volume, and the scope of the data retrieval service which complements it, reflects over 15 years of archive system development supervised initially by David Morris and latterly by Oliver Swain. The British Geological. Survey is responsible for thc acquisition, appraisal and archiving of the featured hydrogeological information. Thc National Groundwater Level Archive is managed by Andrew McKenzie. Over the 1991-95 period, and for many years prior to that, this role was performed by the late Dick Monkhousc whose expertise and commitment did much to establish and maintain a national groundwater level archiving capability in the UK. Prem Doorgakant and, latterly, Rosc Hargreaves have undertaken the data archiving responsibilities and the associatcd liaison with the measuring authorities. Kevin Down supervised the digital prcparation of thc river flow maps featured in this publication. Rebecca White and Felicity Sanderson undertook most of the necessary cartographic editing. John Can was responsible for most of the remainder of the graphics. Some of the features displayed in thc maps contained in this report arc bascd on the Ordnance Survey BaseData GB and 1:50 000 digital data (licence no. GD03012G/01/97) and arc included with thc permission of the Controller of Her Majesty's Stationcry Office © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution. Typeset, printed and bound in the Unitcd Kingdom by William Clowcs, Beccles, Suffolk. The materials used in the production of this volume arc madc from the pulp of trees in managed forests in which every trcc cut down is replaced by at least one more, thus replacing the Earth's resources. HYDROLOGICAL DATA UNITED KINGDOM HYDROMETRIC REGISTER AND STATISTICS 1991-95 A catalogue of river flow gauging stations and observation boreholes together with summary hydrometric statistics Institute of Hydrology British Geological Survey Covcr Photographs Two themes are depicted through thc cover montage. The left and right columns relate to extreme hydrological ev.eritsexpErienCifiduririCthe .p—cri6d1991195:11i Skóricrtheine,that-Of ldifg iirhflnbniuiring, iireniesented by the notable climate, river flow and groundwater level monitoring sites featured in thc central column. Top left: Worcestershire County Crickct Ground, 2/2/95. Following an unusually, wet January, catchments wcrc soddcn throughout the country and floodplain inundations were very widespread in early February; shown herc is the Lowcr Severn in flood. Photo: Stephen Loader Middle: Flooding of the showhouse on thc ncw Summerfield Estatc, Kirkintilloch (Strathclyde), 12/12/ 94, caused by the River Kelvin inundating its broad floodplain. This damaging flood resulted from a broad, slow moving frontal system which caused persistent rainfall over a 48-hour period across a wide geographical arca. Previous peak flows were exceeded in all major catchments in the region. Photo: Andrew Black Bottom: The 'East lisle}, Ponds' in the Chalk headwaters of the River Pang catchment (Berkshire) adjaccnt to the A34 on 13/4/95. Thc ponds result from the intcrscction of the water-table with the ground surfacc within a normally dry valley. Associated problems in East Ilsley were an overflowing village well and flooded cellars (some for over a month), following heavy rainfalls in January and February. Photo: Martin Lees Top centre: Cod Mynnedd automatic weather station at thc confluence of the Rivers Hafren and TanlIwyth within the Institute of Hydrology experimental catchments at Plynlimon (Powys). This site has operated continuously since early 1975, incorporating, oncc proven, a number of innovative instrumental refinements. A ncarby manual climate station has operated since 1968. Photo: Terry Marsh Middle: Spring flow from the Chiltern scarp slope gauged by a thin-plate weir at Wendover Wharf - the earliest extant mcasuring site in the UK. The National River Flow Archive has a record extending from 1841-97 of monthly flows derived from a count of lockages at Tringford, where the water was fed from the Wendover Ann to the Grand Union Canal. Current operators and record curators arc British Waterways. Photo: Terry Marsh Bottom: The overflowing Chilgrove House (West Sussex) borehole in January 1994. The borehole is housed in the shcd in the left forcground, with Chilgrovc House in the background. This borehole is believed to have the longest continuous record of groundwater levels in the world, dating from 1836. During this time it has overflowed very rarely. The 18-day overflow duration in January 1994 is thought to be the longest on record. Ph0(0: Philip Turton Top right: Scammonden Water Reservoir to the west of Huddersfield (West Yorkshirc) in the River Calder catchment on 25/11/95, at the height of the severe drought affecting northern England. At this time the reservoir stocks were being augmented by supplies brought by tanken. Photo: Pam Moorhouse. Middle: An obvious low flow over the Flat V wcir on the River Brant (Broughton, Lincolnshire) on 22/8/94. The Brant drains a flat catchment typically of Liassic clays and has a fairly responsive rcgimc. Low flows are sustaincd from river sands and gravels and spring seepage from the Lincolnshire Limestone. The cast of England suffered persistently dry conditions throughout much of 1991-95 with the result that many flow estimates, even from structures, would be subject to significant uncertainty. Phow: Environment Agency Anglian Region Bottom: Dry streambed of the River Ver (Hertfordshire) at Redbournbury Mill in the spring of 1991. This follows an exceptionally dry I2-month period but the drought conditions were exacerbated by substantial groundwater pumping in the Vcr catchment for public watcr supply. The Ver was included in the National River Authority's (now the Environment Agcncy) Alleviation of Low Flows scheme and the rehabilitation programme is well advanced. Phow: Terry Marsh HYDROMETRIC REGISTER AND STATISTICS 1991-95 FOREWORD Hydrometric data provide the foundation for both the science of hydrology and for water management generally. The usage of such data is at an unprecedented level in the UK, a reflection of the public and scientific interest in the effects of the recent exceptional climatic volatility. A cluster of notable flood events in Scotland and a sequence of severe droughts in England have underlined our continuing vulnerability to hitherto unusual climatic conditions and fuelled speculation regarding the hydrological implications of climate change in the UK. One consequence is a priority requirement to establish hydrological benchmarks in ordcr to help identify and quantify any sustained dcpartures from the overall stability that characterises river flows and groundwater levels throughout the 200 years or so for which instrumental records arc available. The primary role of the Hydrological data UK series of publications is to document hydrological conditions and increase accessibility to nationally archived hydrological data. The National River Flow and National Groundwater Level Archives constitute a unique resource - allowing thc current notable climatic variability to be examined in a lengthy historical perspective. However, capitalising fully on the large volume of hydrometric data routinely collected in the UK, and assessing the significance of the recent widc departures from the normal seasonal patterns of river flow and groundwater replenishment, is far from straightforward. River flows and groundwatcr levels throughout the UK reflect more than just the incidence of rainfall and the magnitudc of evaporation losses; they are also affected by land usc change and, especially, thc evolving and complex pattern of water utilisation. To properly exploit the considerable investment in hydrometric monitoring in the UK it is essential to have ready acccss to appropriate reference and spatial information. A major objective of the Hydrometric Register and Statistics 1991-95 is to serve as a reference source both to the datasets available and as a guidc to assist in the interpretation of analyses based on the data. This volume, like its precursors, also stands as a testament to the diligence and commitment of the many hydrometric persoimel throughout the UK without whose unstinting efforts the quality and continuity of the national hydrometric archives would be undermincd. The work of the National River Flow and Groundwater Level Archives is overseen