Human impacts on fluvial hydrosystems

For thousands of years rivers have been altered by many forms of human activity. Deliberate changes of fluvial hydrosystems have resulted from the power of technology to satisfy the many demands upon water resources. River regulation by dams for domestic and industrial water supply and for irrigation, which today often include intercatchment transfers, and for flood control has markedly altered the flows, sediment loads and water quality characteristics of many rivers (Petts, 1984). Channelization for navigation and land reclamation has further altered the ecological character of fluvial hydrosystems by isolating the channel from its floodplain (Brookes, 1988). These direct impacts have been compounded by indirect impacts associated with the range of land-use changes that have altered the catchment areas over the period of human occupation — several thousand years in some cases.