Assessing Water Management Challenges and Capacities in African Cities 79
increase in the future, but also the likely spatial dimensions of this demand, and how this relates to the spatial distribution of current and potential future supplies.
Climate Change Will Have an Impact on Urban Water Management While little information is available about future climates at the city level, some information about future hydrology at the catchment level is available.10 The basin is a relevant intermediary scale to provide information about the catchments upon which cities depend for water supply. In Table 3.1 we present an analysis of future hydrology at catchment level in accordance with World Bank methodology (Strzepek et al., 2011). The analysis utilizes five hydrology indicators (measures of changes in mean annual runoff, slow onset floods, droughts, storage, and groundwater) to assess the potential impact of climate change on water resources. The table illustrates the likelihood of lower (higher) values of these indicators for the city-relevant catchment.11 Unfortunately, for most cities in Africa and for most of their indicators, there is little agreement among the climate models. To a large extent this reflects the limited ability of the climate models to model weather in Africa. This again reflects the paucity of historic climate data for Africa and the difficulties that the models have in modeling both the oscillations such as the El Niño Southern Oscillation and the expected frequency and impact of convective storms.