Geomorphic Evolution of the River Cannels after Dam Construction: (A Case Study of Sahand Dam in Tabriz)

In order to use the energy and irrigation potential of the rivers, a series of dams have been designed. Dams have served society for over 4500 years.They control stream flow and secure water storage and act as geomorphic agents and water management structures. Dams profoundly impact the geomorphology of rivers by altering the natural patterns of water sediment and energy flow in those rivers. The effects of dams in downstream geomorphology are reviewed and a typology is devised consisting of 9 cases. The classification can be seen as a balance between water discharge, sediment load, grain size and river slope. Depending on changes in released water flow and changes in released sediment load, relative to transport capacity of the flow, it is possible to estimate resulting cross-sectional geomorphology.The longitudinal extent of changes and their variability with time and the tributary response to altered mainstream cross-section changes are also discussed.