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Groundwater - river interaction in a chalk catchment: the River Lambourn, UK

Grapes, Timothy Rupert (2004)
Ph.D. thesis, University of Birmingham.

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Abstract

Chalk streams are of high ecological value and are dependent upon groundwater discharge to support flows. This study investigates chalk stream-aquifer interaction, focusing on a near-natural catchment; the River Lambourn of the West Berkshire Downs. The topographic catchment of the Lambourn is 234km\(^2\), principally underlain by Upper Chalk. The river has a perennial length of c.16km, and a 7.5km seasonal section.

Temporal dynamics of the recharge-storage-discharge sequence are investigated using linear regression techniques to identify the lag between recharge and discharge. The effective maximum duration of groundwater flow is 9.1 months, which is used with regional hydraulic gradients to calculate a bulk (interfluve) hydraulic conductivity of 114m/d (using Sy=1%), suggesting that interfluve permeability has been historically underestimated.

Spatial flow accretion on the Lambourn is defined from 12 reaches (each 1-2km long), exhibiting mean accretion rates between -0.019 and 0.211 cumecs/km. The accretion rate profile approximates a sinusoidal pattern \((\lambda\)=12km) suggesting a catchment scale litho-structural control. However, local topography and lithology also exert influence. High accretion rate reaches are associated with major dry valley intersections and elevated valley floor permeability, whilst the presence of Chalk Rock at shallow depths restricts local accretion.

Type of Work:Ph.D. thesis.
Supervisor(s):Bradley, Christopher and Petts, Geoff and Bradford, Richard B
School/Faculty:Schools (1998 to 2008) > School of Geography, Earth & Environmental Sciences
Department:School of Geography, Earth and Environmental Sciences
Keywords:groundwater, river, interaction, surface water, chalk stream, chalk aquifer, permeable catchment, berkshire downs
Subjects:GB Physical geography
Institution:University of Birmingham
ID Code:4036
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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