The Challenges of Water Supply for A Megacity: A Case Study of Lagos Metropolis

ABSTRACT

Lagos State has grown from 300,000 and 500,000 in 1950 and 1991 to an unprecedented population of 15.7 million (Mabogunje, 2002). Already, it is projected to have a population of 25 million by 2015 which will make Lagos the third largest megacity after Tokyo and Bombay and a population of 29 million by 2020, with an annual growth rate of 8 %( UNCHS, 1996; George, 2010; LWC, 2011). This scenario presents enormous emerging challenges as well as opportunities that are numerous, diverse and inevitable. This geometric population growth, coupled with accelerated industrialization and urbanization, has contributed immensely to the hydra-headed problems of water scarcity, uneven and inadequate pipe-borne water distribution and transmission, increased exposure to incidence of water-borne diseases such as typhoid and cholera leading to loss of lives and valuable man-hours. There is increased reliability on unwholesome water sources such as “pure” water sachets, polluted surface and underground waters, and increased urban poverty owing to a combination of the above problems, the increased cost of production for industries and increased distribution losses (Akunyili, 2003). The major elements of water supply include surface and groundwater sources, water-treatment works-primary, secondary and tertiary, and pipe distribution systems. Lagos Metropolis and its environs are served by three (3) major waterworks, twenty-seven (27) mini-waterworks, out of which fifteen (15) were recently commissioned and ten (10) micro-waterworks, w ith a combined production capacity of 240MGD, w hich meets about 40% of current demand (LWC, 2011). The rivers which traverse the state, namely Rivers Ogun, Oshun, Aye, Owo, Yewa, Iju all combine to produce a total safe yield of 3,565 MLD. The groundwater aquifer under the state located in the Coastal Plain Sand and Abeokuta formations at a depth between 600-800m is capable of a total yield of 650, 000 m3 /day (Oyegoke, 1986; Longe et al, 1987; Coode, 1997). An estimated $3 Billion w ill be required for massive water infrastructural development within the next ten years according to Lagos State Government while $3.7389B investment is required to produce 3954 MLD (870MGD) which is enough to meet the year 2025 forecasted demand of 3900 MLD according to Challenge International Associates (2006). This can only be met by Public -Private Partnerships while concerted effort is made for investment recovery.

KEYWORDS: metropolis, waterworks, demand, population, groundwater, surface water, water supply.