Over the centuries, surface and ground waters have been a source of water supplies for agricultural, municipal and industrial consumers. Rivers have provided hydroelectric energy and inexpensive ways of transporting bulk cargo between different ports along their banks, as well as water-based recreational opportunities, and have been a source of water for wildlife and its habitat. They have also served as a means of transporting and transforming waste products that are discharged into them. The quantity and quality regimes of streams and rivers have been a major factor in governing the type, health and biodiversity of riparian and aquatic ecosystems. Floodplains have provided fertile lands for agricultural production and relatively flat lands for roads, railways and commercial and industrial complexes. In addition to the economic benefits that can be derived from rivers and their floodplains, the aesthetic beauty of most natural rivers has made lands adjacent to them attractive sites for residential and recreational development. Rivers and their floodplains have generated and, if managed properly, can continue to generate substantial economic, environmental and social benefits for their inhabitants. Human activities undertaken to increase the benefits obtained from rivers and their floodplains may also increase the potential for costs and damage when the river is experiencing rare or extreme flow conditions, such as during periods of drought, floods and heavy pollution.