Ponding the Waters: Impacts of Dams
As we’ve covered in the first part of this module, the need for dams is largely driven by the uneven distribution of precipitation, resulting from river discharge, and thus water supply – in both time and space. Dams control river flows and provide capacitance in the river channel to satisfy demands for continuous water supply (i.e. for irrigation and domestic use, for flood control, and power generation). However, such large-scale alteration of the natural river has wide-ranging impacts both upstream and downstream, where the ecology, geology, hydrology, and human populations have evolved in tandem with undisturbed patterns of variable river discharge. Here we’ll briefly cover some of these impacts, and highlight using examples from well-known case studies including the Three Gorges and Aswan High Dams.