African Wildlife & Environment Issue 80

CONSERVATION

To answer this question in an empirical sense, she used a global dataset, processed using the concept of water crowding. She reduced the known water supply of each country into 'flow units', which she defined as one million litres per annum. This enabled her to compare apples with apples. Using this methodology, she was able to determine a water crowding index for each country, at that moment in time. From that data she was able to define what she called a 'water barrier' beyond which no known country was able to retain social stability and sufficient economic growth to employ the growing population. However, her work also isolated a key variable that could alter this outcome. That key variable is technology which made it possible for any country to sustain a viable economy, with sufficient social cohesion, beyond the 'water

barrier' of 2,000 people per 'flow unit' of one million litres of water per annum. This concept became known as the 'hydraulic density of population'. The concept of water crowding is therefore a useful policy tool, because it enables decision- makers to comprehend precise thresholds beyond which existing policy is no longer viable. For example, the policy of achieving national water security by constructing dams and transferring water from one river basin to another, is only viable to a point. Once the sustainable yield in each river basin is reached, that basin is said to have reached a point of 'resource closure', beyond which dam-building is no longer viable, and consequently social stability is no longer attainable from that specific solution (Ashton & Turton, 2008).

The Katse Dam on the Malibamatso River is one of the highest (185 m), and the deepest and coldest dams in Africa. Water is transferred from Katse to Gauteng via a 45 km transfer tunnel to Muela, and from there via a 37 km delivery tunnel to the Ash River. February 2009. Photograph: John Ledger

12 | African Wildlife & Environment | Issue 80 (2021)