That cost comes mainly in the form of the degradation of the donor river systems, a severe decline in species and habitat biodiversity, and impacts on the lives and livelihoods of those depending on healthy rivers. 6 Can it learn from the past and proceed more carefully? Moving along the development pathway a few decades behind more industrialized economies, Africa will face, perhaps more than any other region, a challenge to develop and manage its water resources without repeating the mistakes made by others. Water resource development to meet this growth is inevitable and will take place under the scrutiny of Sustainable Development Goal 6 (SDG 6: clean water and sanitation) and SDG 15, which weakly addresses inland waters as a subsection of life on land.

5 Its human population, presently 1.4 billion or 17 percent of global numbers, is predicted to reach 4.5 billion by 2100 (40 percent of global). It is a low- to medium-income continent with six of the world's fastest-growing economies. Africa, with about 9 percent of the world's freshwater resources, is a prominent part of this growth.

3 From 1970 to today, there has been a doubling of the world's human population, a fourfold increase in the global economy, and a tenfold increase in trade. The UN predicts it will reach eleven billion by 2100 in what appears to be a slightly flattening trajectory.

The world population stood at five million people in 8000 BC, one billion in 1800, and seven and a half billion in 2017.

Fred pearce when the river runs dry