SEDL / STP / STP1288-EB / STP38395S

Modelling Groundwater Source Catchments in The UK: Implementation and Review of A Qualitative Method for Representing Uncertainty.

Fermor, MM
Environmental Manager, Water Management Consultants Ltd, Shrewsbury,

Morris, BL
Principal Hydrogeologist, National Rivers Authority, Groundwater Centre, Solihull, West Midlands

Fletcher, SW
Senior Hydrogeologist, NRA, Severn Trent Region, Solihull, West Midlands

Pages: 17    Published: Jan 1996

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Abstract

The UK National Rivers Authority Groundwater Protection Policy seeks to restrict certain polluting activities in the catchments and defined time of travel zones (TOTZs) to potable groundwater sources The size, shape and location of catchments and TOTZs is controlled to a great extent by factors which are poorly defined. A practical qualitative method was developed to represent parameter uncertainty within the context of deterministic modelling (finite difference steady state 2D). Plausible models of the groundwater systems were developed by a standardised procedure so that some of the uncertainties could be represented, and a simple postprocessing technique was developed to provide a geographic representation of zones which are predicted to be definitely within the catchment or TOTZ (Zone of Confidence) or potentially within the catchment or TOTZ (Zone of Uncertainty). A summary of the experience of the first 133 sources zoned is presented.