In-Depth Analysis of Water Management Challenges in Selected Cities 85
Figure 4.1 Estimated Range of Future Water Demand for Nairobi, Kenya, 2010 to 2035 2,000,000 High estimate (this study)
1,750,000
m3/day
1,500,000 Medium estimate (master plan)
1,250,000 1,000,000
Low estimate (this study)
750,000 500,000 2010
Year
2035
Source: World Bank, based on water master plan estimate from (AWSB, 2012). Note: m3 = cubic meters.
Decentralization creates additional uncertainties about future conditions for bulk water supply to Nairobi. The new constitution of Kenya will result in a stronger role for lower levels of government by allocating to county governments the responsibility for public works and services, including water and sanitation. Water resources cross counties and regions, and, while they will remain a national resource, there will need to be agreement on specific management arrangements. For Nairobi, which imports most of its water from the Tana basin outside Nairobi county, such disagreements might cause uncertainty about the access to and the cost and reliability of these surface water resources. IUWM is a potentially powerful approach to water security through diversification in Nairobi. As an adaptive system, IUWM options in Nairobi’s future water system can provide water security within a much wider range of future water demand and supply scenarios and can help offset or defer bulky investments in conventional water resources. Even though each of the proposed options only provides a small gain individually, in combination they can provide a more significant contribution to the solution of the water resource challenge in Nairobi. The proposed IUWM options include water demand management, leakage management, stormwater harvesting, and greywater recycling. It is suggested that the options be implemented at the household, cluster, or city level depending on the policy scenario chosen by decision makers. Not all scenarios include all options.1 When the quality of water is matched with its intended purpose, there are more options for diversification. Figures 4.2 and 4.3 compare the