Browsing by Author "Baron, Jane Helen"

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    Groundwater management using a GIS case study : Uitenhage Subterranean Government Water Control Area
    (2000) Baron, Jane Helen; Whittal, Jennifer; Butcher, Shirley
    The area around Uitenhage in the Eastern Cape forms the centre of one of the biggest artesian groundwater basins in South Africa. The Table Mountain Group quartzitic sandstones are overlain by a thickness of postPalaeozoic sediments giving rise to artesian groundwater. The most wellknown of this manifestation are the springs at Uitenhage which have been used since pre-historic times and are currently a principal source of water for the municipal supply. At the turn of the 20th century, with the introduction of drilling machines into the area a number of boreholes were constructed. The resultant tapping into the artesian supply resulted in the spring-flow lessening and a decline in groundwater levels on introduction of further boreholes. At the request of the local community this special region was proclaimed a groundwater protection area. Over the years the abstraction within the area has risen and is currently at 3.24 million m³/a. However the licensed, legally abstractable, figure stands at 6.15 million m³/a. Groundwater levels have declined although the flow from the boreholes has not. Using GIS aU the available and pertinent information required for the management of the control area and for the estimation of the groundwater resource has been brought together. Using raster modelling techniques the amount of groundwater available within the system and the viability of sustained abstraction were assessed. A site-specific raster model has been designed to visualise and quantify the expected effects of new boreholes in the area.