Costs Versus Benefits Of River Regulation.

Essay by axeman69High School, 11th gradeA-, May 2003

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River regulation is any man made structure that interrupts a waterway for the purpose of regulating the flow to allow a more constant supply. This regulation of waterways has many costs and benefits associated with it and affects both the submerged areas and the downstream reaches of the stream. This essay will compare the costs versus benefits of such river regulation.

When a river has a dam, weir, or diversion built on it the water is held back or redirected. This, in turn, has a major affect on the submerged areas and downstream reaches of the river. If the water is held back to make an artificial lake or regulate the flow then whatever is in the newly submerged areas is destroyed. As the water builds up behind the dam wall the costs are: river scenery is submerged, trees die and leave the river open to erosion, animal habitats are lost, land that may already be in use for agriculture is lost, important sand and sediment, that should nourish the downstream reaches is caught at the dam wall, water temperature is modified which can kill native species of water flora and fauna, the chemistry of the water can change, water quality may deteriorate because it is more stagnant, food webs are restructured (e.g.

micro plankton may become the prominent life form because the factors necessary for its survival are increased as happened in Sydney's major dam), annual migration of certain species is blocked by the dam wall (e.g. salmon), new flood plains are established, water levels fluctuate as water is released downstream, the dam may need to be restocked with fish every year, and the possible relocation of towns or individual dwellings (e.g. in the 1930's when the Hume dam was built of that Murray River the Victorian township of...