This is an IAH Technical Discussion Meeting based on a talk given by Henning Moe at the 44th Annual Congress of the IAH, Dubrovnik.

Abstract

Dar es Salaam (DSM) is the largest city and economic engine of Tanzania. Recent years have brought significant and unsustainable growth to DSM, and both planners and utilities are struggling to cope with the pressures that accompany urban growth, which includes an asymptotic water demand curve.

Funded by the Government of Norway, a major groundwater exploration and assessment project was undertaken to test a conceptual hydrogeological model which places a regional coastal aquifer system at the doorstep of DSM. Results of the assessment verified the concept and the new resource is estimated to have a sustainable supply potential of more than 200,000 m3/d.

Implementation of the Kimbiji Aquifer project bridged the oil and water sectors, whereby onshore and offshore hydrocarbon exploration data were used to interpret the architecture and geometry of the aquifer system. Without these data, it would not have been possible to place boundaries on the system or estimate its total thickness or volume. Nothing similar has been attempted in Tanzania before, and initial scepticism about the new resource was quickly replaced by expectation.

The hydrogeological assessment work included the drilling, geophysical logging and testing of 600 m deep exploration boreholes, numerical groundwater modelling and water quality characterisation. Specific outputs were an Aquifer Development Plan and a Strategic Environmental Assessment of the proposed plan. Results will assist regional and national authorities to make informed planning decisions, and to both scope and cost infrastructure requirements over a 30+-year planning horizon.