Where have all the rivers gone?

Abstract

The dramatic change in the Colorado River (US) since Leopold's journey in 1922, is not an isolated case of extraction exceeding a river's capacity to maintain its flow. Attempts to control rivers, particularly by dam building, have a long history, and they have wreaked havoc on the aquatic environment and its biological diversity. Case studies of the Colorado and the Nile illustrate the problem. The examples of Lake Chad and the Aral Sea demonstrate the severe consequences of depletion where rivers empty into inland lakes or seas. Dry season extraction creates problems in Asia such as those experienced by Bangladesh over the use of the Ganges. More straightforward are the problems of Thailand's Chao Phraya basin and along China's Yellow River. Restoring and maintaining the integrity of river systems will involve new technologies, policies and management strategies. The difficulties encountered are illustrated and details of some creative solutions are set out. -D.G.Price