Abstract
Abstract Maputo, the capital of the People's Republic of Mozambique, with about 1 million inhabitants, faces serious water supply problems. It is expected that at the end of 1989 surface water supply will be increased to 6 000 m 3 /hr. This amount will meet the demand of the canalized parts of the city in 1989. Groundwater exploitation contributes another 1 200 m 3 /hr. Lack of funds and executing capacity for a canalization programme connecting the suburbs forced the National Directorate for Water Affairs (DNA) to start intensive exploitation of the regional dune and (calcareous) sandstone aquifers. Besides this the intensification of agriculture in the coastal zone and a river valley near the city resulted in another groundwater demand. Future urban water supply will also depend partly on the exploitation of groundwater. The regional aquifers are of limited extension. Analysis of existing and new geohydrological information and geophysical surveys resulted in a detailed knowledge of aquifer parameters, groundwater levels and the position of the fresh/salt water interface. Separate studies gave data on the recharge. A quasi-3-dimensional groundwater model has been applied to evaluate the various extraction policies. Key parameters are groundwater levels and the position of the fresh/salt water interface. Protection areas have been defined. A choice has been made for the restriction of some areas to exploitation of groundwater only for agricultural use. A cost/benefit analysis of this type of exploitation is presented. As a consequence of this decision the costs of future city water supply by groundwater exploitation will increase, as the allocated area for this objective is 30 km north of the city. To prevent overexploitation of the aquifers DNA introduced a system in which all new boreholes need the autorization by DNA.
Published Version
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