While developed countries have substantial resources available to spend on addressing water issues, developing countries often have far fewer resources, and as a result, water stress can be a much greater problem. In Africa, for example, despite abundant water resources at the continental scale, only 4% of the total available freshwater supply is currently accessed for human use (UN, 2007), thereby creating water stress problems in many African countries. Consequently, worldwide assessments of water resources can be misleading and measures of water stress need to be undertaken at a regional scale which accounts for both demand and supply of water, as well as the level of economic development.