Modelling groundwater/surface water interaction in a managed riparian chalk valley wetland |
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| Authors: | A R House J R Thompson J P R Sorensen C Roberts M C Acreman |
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| Institution: | 1. Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford, Oxfordshire, UK;2. UCL Department of Geography, University College London, London, UK;3. British Geological Survey, Crowmarsh Gifford, Wallingford, Oxfordshire, UK |
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| Abstract: | Understanding hydrological processes in wetlands may be complicated by management practices and complex groundwater/surface water interactions. This is especially true for wetlands underlain by permeable geology, such as chalk. In this study, the physically based, distributed model MIKE SHE is used to simulate hydrological processes at the Centre for Ecology and Hydrology River Lambourn Observatory, Boxford, Berkshire, UK. This comprises a 10‐ha lowland, chalk valley bottom, riparian wetland designated for its conservation value and scientific interest. Channel management and a compound geology exert important, but to date not completely understood, influences upon hydrological conditions. Model calibration and validation were based upon comparisons of observed and simulated groundwater heads and channel stages over an equally split 20‐month period. Model results are generally consistent with field observations and include short‐term responses to events as well as longer‐term seasonal trends. An intrinsic difficulty in representing compressible, anisotropic soils limited otherwise excellent performance in some areas. Hydrological processes in the wetland are dominated by the interaction between groundwater and surface water. Channel stage provides head boundaries for broad water levels across the wetland, whilst areas of groundwater upwelling control discrete head elevations. A relic surface drainage network confines flooding extents and routes seepage to the main channels. In‐channel macrophyte growth and its management have an acute effect on water levels and the proportional contribution of groundwater and surface water. The implications of model results for management of conservation species and their associated habitats are discussed. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | wetlands hydrological/hydraulic modelling groundwater/surface water interaction MIKE SHE wetland management |
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