13.6 Future impacts on provision of water
13.6.1 Population dynamics
Rapid population growth puts increasing pressure on our limited resources. The percentage of young children is increasing within the Ethiopian population. In 2007, a Central Statistics Agency report estimated the Ethiopian population as 73 million, of whom about half are under 15 years of age. This means an increase in the proportion of the total population at highest risk from infectious waterborne diseases (gastrointestinal illnesses disproportionately affect the health of the very young and very old).
The general increase in population means that more and more land is brought into use to support the growing number of people. This can have a serious impact on the environment and also on water resources. There is a close relationship between land use, and water quality and quantity. If land is cleared of natural vegetation, water will run off the surface more quickly and will not soak into the soil. This not only reduces the amount of soil water available for plant growth it also reduces replenishment of groundwater reservoirs. The water flows off into rivers before it has penetrated into the ground. The increased runoff resulting from loss of vegetation also causes soil erosion, especially in the rainy season, because the soil is washed away into the rivers. Erosion is especially likely on slopes and where the ground is ploughed, which loosens the surface layers. The eroded soil particles run off into the rivers and make the water very turbid (muddy). The loss of natural vegetation, especially forest, also means a loss of biodiversity, i.e. a reduction in the number of different types of living organisms of all types that exist in an area.