Assessment of a New Dam Site for Water Supply Potential in Bauchi Metropolis, Nigeria

Abstract

The maximum yield of 90,000 m3 /day from the existing Gubi dam in Bauchi will barely meet the water demand beyond 2030 at an average water use of 100 litres per capita/day. For higher water demand of up to 250 litres per capita/day expected in an urban centre, the existing dam capacity is inadequate, and the demand should grow to 253,102 m3/day by 2037. This is the rationale for this study, which showed the feasibility of a new dam through technical reviews and analysis of topography, hydrology of the site, field and laboratory investigations, computer analyses and designs. Hydrologic simulation of rainfall-runoff processes for 57 years of rainfall data using the Soil Conservation Service (SCS) method gave an annual runoff volume of 59 Mm3 on a stream in Miri, which can be harnessed to assure adequate water supply in the metropolis. This will require the construction of a 25 m high embankment dam. Topographic survey and analysis indicated that the proposed site has good water retention capability. Although net flow adjustment analysis showed a high evaporation loss of up to 13.5 Mm3 annually, seepage loss is expected to be small in view of the underlying basement complex rock formation.