Integrated Catchment Modelling as a Water Resources Management Tool

Abstract

Groundwater models are becoming increasingly important in water resources management. Most aquifers in the UK are closely linked with river systems, to which they contribute baseflow from seepages and springs. As a result, major groundwater abstractions almost inevitably affect river flows. To assess with confidence the effect of utilizing groundwater resources, an aquifer and river system has to be linked within an integrated model which can simulate varying hydrogeological conditions throughout the catchment.The main features of an integrated catchment management model, which links aquifer and river systems, are described in this paper. The model has been applied to a number of catchments in southern England including the River Darent in Kent, which is probably the most well-known and worst-affected of all rivers identified nationally as suffering from overabstraction.The process of model preparation and calibration is illustrated with reference to the River Darent. Twenty years of river flow and groundwater hydrograph records were used in producing a close simulation of modelled and actual hydrological conditions. The model was then operated to assess a large number of possible options for restoring flows to the river. Examples of various management strategy simulations are given, leading to formulation of a water resources management plan for the Darent. This involved (a) reductions in selected abstractions, (b) flow augmentation using river support boreholes, and (c) meeting peak groundwater supply demands in drought periods.

Using environmental tracers to assess the extent of river–groundwater interaction in a quarried area of the English Chalk

“…However, stable isotope and tritium data from the river and public supply boreholes suggest that between one-fifth and one-third of abstracted water is derived from the river in the lower part of the valley. While there are uncertainties over the exact figure, it would be consistent with the view based on regional modelling that below Lullingstone the river is frequently perched above the groundwater table (Rippon & Wyness, 1994), with consequent potential for some river loss. This combined use of isotopic and trace gas indicators has provided new insights into the hydrogeology of an area where development pressures mean a balance must be struck between environmental amenity and water supply.…”

“…In the context of the proposed abstraction from the Swanscombe Block for public water supply, the hydrogeology of the area is a sensitive issue because the River Darent, an ecologically-important Chalk stream, partially dried up in the 1990s (Rippon and Wyness, 1994). In addition, the river approaches to within 3 km of the quarries and the possibility of sub-karstic leakage from the river to the quarries has been raised.…”

Interdependence of groundwater and surface water in lowland karst areas of western Ireland: management issues arising from water and contaminant transfers

“…The fact that groundwater discharge is the main component of river baseflow, and the differences in the storage and transmission of surface water and groundwater, have encouraged the establishment of conjunctive management schemes in many suitable environments, as documented in Misstear (1999), Winter et al (1998) and Rippon & Wyness (1994), for example.…”

Groundwater Development in England

“…In the 'groundwater drought' of 1988 to 1993, stretches periodically dried up completely (Herbertson, 1994;Rippon and Wyness, 1994). The historical background is described.…”