102 The Future of Water in African Cities
Groundwater has significant potential as a water source in Arua and its surrounding areas, but protection is key. Analysts (Gauff, 2011; Universal Water Consultants Ltd., 2011) have identified a large number of wells and suggest that yields are sufficient to augment the limited surfacewater supplies. In accordance with the cluster approach to water management, Eckart et al. (2012b) suggest that where possible, each cluster have its own independent groundwater source. However, reliance on groundwater for water supply requires that the poor sanitation that is currently in danger of polluting groundwater be dealt with. Water sources must be protected through integrated solutions. Eckart et al. (2012b) propose a system of greywater or wastewater recycling. In all cases households are only supplied with potable water and separation only takes place for water leaving households. In clusters, where there is surface water available for blending with recycled water, greywater is treated in DEWATS and then combined with treated surface water to provide potable water supply (see Figure 4.13 and Figure 4.14). In clusters, where there is limited surface water available for blending, wastewater is treated and used for groundwater recharge. Figure 4.13 Staged Development of Water Resources, 2010 to 2035, for IUWM in Arua, Uganda Water demand
Existing water supply
Future water supply sources
20,000
Greywater (Cluster 6, 8, and 9)
Water demand/supply, m3/d
18,000
Wastewater re-use (Cluster 3, 4, and 5)
16,000 14,000
Upgrading abstraction (Enyau River)
12,000
Greywater (Cluster 1, 2, and 7)
10,000 8,000
Surface water (Dam at Enyau River)
Groundwater
6,000 4,000 2,000
Surface water—Enyau River (existing operating capacity)
20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21 20 22 20 23 20 24 20 25 20 26 20 27 20 28 20 29 20 30 20 31 20 32
0 Year Source: World Bank. Note: The figure shows the years at which the different water sources need to be developed to meet the growing water demand in Arua. The volume of water supplies from each source has been determined based on meeting medium-term water demand projections. Some of the sources might need to be developed at the same time (for example, upgrading abstraction from the Enyau River and greywater in clusters 1, 2, and 7). m3/d = cubic meters per day.