Backwater (river)

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A house Boat View from Vembanad Lake

A backwater is a part of a river in which there is little or no current. It refers either to a branch of a main river which lies alongside it and then rejoins it or to a body of water in a main river which is backed up by an obstruction such as the tide or a dam.[1]

Alternative channel[edit]

A Kerala House boat in Kumarakom, India

If a river has developed one or more alternative courses in its evolution, then one channel is usually designated the main course and secondary channels may be termed backwaters.[2] The main river course will usually have the fastest stream and will likely be the main navigation route, whereas backwaters may be more shallow and flow more slowly if at all. This results in a more diverse environment that is of scientific interest and worthy of preservation.[3][4] Backwaters also provide opportunities for leisure activities such as canoeing and fishing.[5][6]

In this sense, the term is extended to apply to physical and social areas that have been by-passed. It may apply to places that have been neglected in economic development[7] or in the expression a "cultural backwater".[8]

Water backed up by an obstruction[edit]

When a section of a river is near the coast or another feature that sets its base level, then the section which is influenced by the conditions at its mouth is termed a backwater. If a river flows into a lake or sea, this is the region in which the slope of the river decreases because the lower water flux permitted at the mouth causes the water to back up. Where the river outlet is strongly affected by tides, this cyclic change in base level changes the portion of the river that is a backwater. As a result, fresh and salt water may become mixed to form an estuarine environment.[9]

See also[edit]