1991 YEARBOOK INSTITUTE OF HYDROLOGY • BRITISH GEOLOGICAL SURVEY I HYDROLOGICAL DATA UNITED KINGDOM 1991 YEARBOOK © 1992 Natural Environment Research Council Published by the Institute of Hydrology, Wallingford, Oxon OX 10 8BB ISBN 0 948 540 43 5 Editor Hydrological data UK series T J Marsh Assistant Editor S J Bryant The acquisition, archiving and validation of the bulk of the. hydrological data featured in this Yearbook is undertaken as part of the National Water Archive (NWA) project at the Institute of Hydrology. Under the ieadership of M L Lees (NWA Manager) a team of regional representatives is responsible for liaison with the measuring authorities (see page 172). In addition to the editorial staff, this team currently includes:- N W Arne 11, D B Boorman, J D Dixon, I G Littlewood, S C Loader and D G Morris. The style and contents of the Yearbook, and the scope of the data retrieval service which complements it, reflects a decade of archive system development supervised initially by D G Morris and latterly by R MacRuiri. The British Geological Surveyi is responsible for the acquisition and archiving of the featured groundwater level data. R A Monkhouse is the Groundwater Level Archive manager and provides hydrogeological appraisal and advice relating to the groundwater material which appears in the Yearbook. The associated archiving and measuring authority liaison duties are undertaken by P Doorgakant. S Black was responsible for the pieparation of the text and supervises the sale and distribution of the Hydrological data UK publications thrOugh the National Water Archive Office at the Institute of Hydrology Design: P A Benoist Graphics: J J Carr Typeset and printed in the United Kingdom by Burgess. The materials used in the production of this volume are made from the pulp of softwood trees in managed Scandinavian forests, in which every tree cut down is replaced by at least one more, thus replenishing the Earth's resources. Cover: The River Ver near Redbournbury Mill upstream of St. Albans. Photograph: Terry Marsh HYDROLOGICAL DATA UNITED KINGDOM 1991 YEARBOOK An account of rainfall, river flows, groundwater levels and river water quality January to December 1991 Institute of Hydrology British Geological Survey á HYDROLOGICAL DATA: 1991 FOREWORD 1991 saw a continuation of the very unusual climatic conditions which have characterised much of the United Kingdom since early in 1988. Over the ensuing four years, a substantial disturbance to the average rainfall patterns heavily accentuated the normal contrasts between the wettest and driest pans of the country. Whilst northern Scotland has had to cope with a number of notable flood events, eastern and southern England has been afflicted with a very persistent rainfall deficiency. The threat posed by the remarkably protracted drought in the English lowlands to water resources and the aquatic environment has attracted widespread scientific and public debate. The need for comprehensive data and authoritative documentation to inform this debate has never been greater. A principal function of the Hydrological data UK series is to disseminate information relating to contemporary hydrological conditions and to provide both a perspec- tive within which to examine the recent exceptional events and a benchmark against which any future changes may be assessed. The Hydrological data UK series of Yearbooks and reports was launched in 1985 as a joint venture by the Institute of Hydrology (IH) and the British Geological Survey (BGS); both organisations are component bodies of the Natural Environment Research Council (NERC). Such a collaborative enterprise arose naturally from the close liaison maintained between those responsible for the manage- ment of the national River Flow Archive at IH, and their counterparts at BGS concerned with the national Groundwater Level Archive. This collaboration was reinforced in 1992 by the inclusion of both archives as core datasets in the newly created National Water Archive, the latest of NERC's Designated Data Centres. A major objective of these Centres is to increase the use and utility of basic archived data. I believe that the National Water Archive will make a major contribution to the development of water science and, ultimately, to water management in the UK. The work of the national River Flow and Groundwater Level Archives is overseen by a steering committee which includes representatives of Government departments, the National Rivers Authority and the water industry from England, Wales, Scotland and Northern Ireland. Professor W.B. Wilkinson Director, Institute of Hydrology National Rivers Authority region or River Purification Board boundary Hydrometric area number and boundary 1)3/43/43/43/4._2. Ntv< 261.143.h p1203 263.T pl 236 . 205 pt226 717/1720(' HYDROLOGICAL DATA: 1991 CONTENTS Page INTRODUCTION 1 SCOPE AND SOURCES OF INFORMATION 2 Rainfall and climatological data 2 HYDROLOGICAL REVIEW 3 Summary 3 Rainfall 3 Evaporation and soil moisture deficits 10 Runoff 13 Groundwater 23 1991 Hydrological diary 27 RIVER FLOW DATA 29 Computation and accuracy of gauged flows 29 Scope of the flow data tabulations 29 Gauging station location map 34 Daily flow tables 36 Monthly flow tables 93 THE NATIONAL RIVER FLOW ARCHIVE DATA RETRIEVAL SERVICE 137 List of surface water retrieval options 138 Concise register of gauging stations 140 GROUNDWATER LEVEL DATA 147 Background 147 The observation borehole network 147 Measurement and recording of groundwater levels 147 Index borehole location map 149 Register of selected groundwater observation wells 150 Network changes 150 Hydrographs of groundwater level fluctuations 152 The Register 156 THE NATIONAL GROUNDWATER LEVEL ARCHIVE DATA RETRIEVAL SERVICE 159 List of groundwater retrieval options 160 SURFACE WATER QUALITY DATA 161 Background 161 Data retrieval 161 Water quality monitoring station location map 161 Scope of the water quality data tabulations 162 Water quail°, data tables 164 DIRECTORY OF MEASURING AUTHORITIES 172 PUBLICATIONS in the Hydrological data UK series > 174 ABBREVIATIONS 175 á INTRODUCTION The 1991 Yearbook is the third edition since publishing surface water information in England and responsibility for the publication of data, upon which Wales then passed to the newly created Water Data assessments of water resources in England and Wales Unit of the Department of the Environment (DoE). may be made, was transferred (under the Water Act Yearbooks were published jointly each year by these 1989) from the Department of the Environment to organisations and the Scottish Office for the water- the National Rivers Authority. years 1953-54 to 1965-66; thereafter information It is the eleventh Yearbook in the Hydrological for the five calendar years 1966 to 1970 was data UK series and the first volume in the third five- published in one volume in 1974. Following editions year publication cycle (1991-95). were renamed 'Surface Water: United Kingdom' to The 1991 Yearbook represents the thirty-second mark the inclusion of the first records from Northern edition in the series of surface water publications Ireland and in recognition of the move away from which began with the 1935-36 Surface Water single year volumes. Two volumes of Surface Water: Yearbook. As a result of the incorporation of United Kingdom, covering the years 1971-73 and groundwater data in the Yearbook, this volume is 1974-76 were published jointly by the Water Data also the fifteenth edition in the series of groundwater Unit, the Scottish Development Department (now - data publications which began with the 1964-66 The Scottish Office Environment Department) and Groundwater Yearbook. the Department of the Environment for Northern Apart from summary information, surface water Ireland. and groundwater data on a national basis were Following the transfer of the Surface Water published separately prior to the introduction of the Archive to the Natural Environment Research Hydrological data UK series. In common with the Council in 1982, the final edition of Surface Water: earlier editions, the 1991 Yearbook brings together United Kingdom, for the years 1977-80, was pre- the principal data sets relating to river flow, pared by the Institute of Hydrology at the request of groundwater levels and areal rainfall throughout the the Water Directorate of the Department of the United Kingdom. Also included are water quality Environment, and published in 1983. data for a selection of monitoring sites throughout The 1981 and 1982 Yearbooks were prepared the UK. A comprehensive hydrological review of the concurrently and were, in 1985, the first Yearbooks year includes an examination of the spatial and published by the Natural Environment Research temporal variations in the intensity of the exception- Council. Further Yearbooks - the editions for 1983 to ally persistent drought in eastern and southern 1990 - were published over the following six years. Britain. A compilation of 'Groundwater levels in England An outline description is given of the national during 1963', which was produced by the Geological River Flow and Groundwater Level Archives and Survey of Great Britain (prior to its incorporation the data retrieval facilities which complement them. into the Institute of Geological Sciences), was the Publication of river flow data for Great Britain precursor to the publication of groundwater level started with the series of Surface Water Yearbooks. data on a national basis. The more formal The first edition, which was published in 1938 for Groundwater