28 The Future of Water in African Cities
agement plan. Cotonou in Benin, Accra in Ghana, and Lagos in Nigeria all suffer heavy pollution from industry (Bloch, 2012).
Poor Drainage and Flooding Are a Growing Problem It has been shown in many cities around the world that poor solid waste management can impact urban drainage (UN-Habitat, 2010). A background paper completed for this study (Sen, 2012) found that while progress has been made in solid waste management in some African cities—including testing of different models of primary collection and disposal—little information is available on drainage. Serious episodes of flooding in African cities, however, show that drainage is conspicuous by its absence. A lack of stormwater drainage infrastructure, blocked and poorly maintained stormwater drains, and settlements in previously unsettled low-lying areas have contributed to recurrent urban flooding in many African cities including Bangui, Central African Republic, and Dakar, Senegal. The large exposure to flood hazards and the vulnerability to floods is closely linked to inadequate planning of the urban space, poor access to more distant areas, and poor enforcement of existing regulations. With additional development and possibly more severe storms due to climate change, cities could experience higher frequency, duration, and intensity of flooding events. Sea-level rise could increase the threat in coastal cities. More severe storms and increases in wastewater flows can exacerbate gully formation (as in southeastern Nigeria, see Figure 1.10). Gullies can undermine housing and infrastructure, threaten lives, and damage livelihoods. Traditional solutions to drainage issues might not be sufficient. Solid waste management and drainage are typically a municipal responsibility and wastewater management a utility responsibility; institutional divisions make it difficult to implement plans that crosscut sectors, like those needed for urban drainage. Traditional drainage solutions (deep trenches) are also costly, energy intensive, and vulnerable to poor solid waste management solutions.
These Challenges Are Exacerbated by Climate Variability, Flooding, and Uncertainty about the Future The new urban paradigm in Africa calls for an innovative urban planning and management approach that will allow cities to grow safely and ensure that residents suffer less damage from disasters. As the population