The use of groundwater levels and numerical models for the management of a layered, moderate-diffusivity aquifer
Published:January 01, 2012
M. G. Shepley, R. W. N. Soley, 2012. "The use of groundwater levels and numerical models for the management of a layered, moderate-diffusivity aquifer", Groundwater Resources Modelling: A Case Study from the UK, M. G. Shepley, M. I. Whiteman, P. J. Hulme, M. W. Grout
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The predictions from a numerical time-variant distributed groundwater model are used to assess the spatial and temporal impacts of groundwater abstraction for an unconfined and layered, moderate diffusivity aquifer; the West Midlands–Worfe Permo-Triassic Sandstone in the UK. These impacts have been determined by comparing a recent actual baseline predictive simulation with simulations where groundwater abstractions are switched off, including a ‘naturalized’ simulation. By reference to the historic simulation, the predictive model results are compared against observed groundwater levels. The predictive simulations demonstrate that observed groundwater levels could be an indicator of groundwater abstraction impacts on surface water flows where widespread stream disconnection has occurred due to high rates of abstraction. This relationship also depends on the aquifer hydraulic characteristics, the interaction between groundwater levels and the surface drainage network and other artificial flow influences. Abstraction impacts on groundwater levels are large for the West Midlands–Worfe aquifer, but can be obscured by the climatic recharge signal in observed groundwater level records. This is a consequence of the moderate diffusivity and the main groundwater abstraction development preceding systematic monitoring. The groundwater model can be used to identify which observation boreholes have negligible abstraction impacts; this may be valuable for identifying groundwater level records that are useful for climate change analysis.
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Groundwater Resources Modelling: A Case Study from the UK
The UK is a country with over 150 years of widespread exploitation of its principal aquifers for public water supply. Increasing demands, greater awareness of environmental pressures and more exacting legislation has heightened the need for quantitative models to predict the impacts of groundwater use. In the UK this has culminated in a unique national, regulator-led programme for England and Wales to develop conceptual and numerical models of the principal bedrock aquifers.
The outcomes of this programme will be of interest to the international hydrogeological community, particularly as international legislation such as the European Water Framework Directive requires management of water issues across administrative boundaries with a varied cast of stakeholders.
The collection of papers provides a contrast between practitioner- and research-based approaches to assess and predict the anthropogenic impacts and environmental pressures. Many insights are provided on how the regular use of groundwater models may address the environmental challenges of the future.