Water scarcity in addition to a growing population

Water scarcity in addition to a growing population

My last post dealt with the hydrological variability in Sub-Saharan Africa. To become a better understanding of what climate change does, in this post I will continue with the matters of population growth and water supply, in particular.

Population in Africa has increased during the last decades. Further, population growths are estimated by UNFPA to peak about 119% under low and 193% under high UN variants. According to Parfait et al. (2012: 404), there is also a huge difference between rural and urban trends, because “the share of urban population has more than doubled since independence in the 1960s”. The following graph in figure 1 shows the development of urban and total population in Africa.

Figure 1: Urban population growths and estimated development in Africa. Source: Carter and Parker (2009: 685).

As you can see in the graph above, the population growths started to increase in the 1960, as Parfait et al. (2012) indicated. The urban population is ascents on a constant level without any indication of stagnation. In particular, the percentage of the population living in urban areas, seems to be of great significancy.

The demographic change and the urban-rural inequality are linked to domestic water consumption, as well as groundwater usage. Especially in cities the water consumption per head varies from the African average. While domestic water consumption is about 20 litres per capita, they are not uniformly distributed and the demand in cities is higher. The overall water demand is estimated to increase by at least 154% (Carter and Parker, 2009).

The hydrological variability is intertwined to the groundwater recharge, which is effected by climate, land cover and soil type. A drop mean annual rainfall from 500 to 400 mm leads to a reduction of 80% in the annual recharge (Cavé et al., 2003). Duration and amount of precipitation affects the groundwater and therefore water supply in cities. As the population is growing fast, amount of water need is increasing, but accessible water is beneath. There will a higher water stress index on available groundwater. Figure 2 shows the water scarcity in Africa between 1990 and estimated scarcity in 2025.

Figure 2: Estimation of water scarcity in Africa from 1990 to 2025. Source: http://www.unep.org/dewa/vitalwater/article77.html

The graph illustrates the water scarcity getting worse in the next decade. As decreasing water availability leads scarcity, the population is growing fast (Figure 1). Examining figures 1 and 2 collectively, it is evidence that population growth has, over recent years, exacerbated water availability, rendering it an increasingly scarce commodity.

References:

http://www.unep.org/dewa/vitalwater/article77.html

Cavé, L. , Beekman, H. E. and Weaver, J. (2003): Impact of climate change on groundwater recharge estimation. In: Groundwater Recharge Estimation in Southern Africa.

László J. J. Kulcsár and Katherine J. J. Curtis (2012): Demographic Change and Rural-Urban Inequality in Sub-Saharan Africa: Theory and Trends. In: International Handbook of Rural Demography. Springer Science+Business Media B.V. Wisconsin.