What is ariable?

What is a projects purpose?

A multipurpose project is a large scale hydro project often including dams for water retention , canals for irrigation, water processing and pipe lines to supply water to cites and power generation. These often include transportation improvements and industrial growth. They are also developed to reduce the dangers of flooding. Positives: 1) Eliminates or reduces flooding 2) impounds water for later use - irrigation, human consumption, industrial consumption 3) lake fisheries 4) power generation 5) transporation 6) recreation Negatives They lead to the displacement of human, plants, animals, chiefly from small tribal communities; disrupt downstream fisheries; increase the risk of earthquakes; submerge forest land; increase the spread of insect-borne diseases; and threaten the fragile regional ecosystem through reducing, the flow of water from the rivers into the seas. These projects initially devastate human lives and biodiversity by inundating thousands of acres of forests and agricultural land. They degrade the fertile agricultural soils due to continuous irrigation (rather the seasonal irrigation which is dependent on the monsoon), and salinization, making the soil toxic to many plant species. Multi-purpose river valley projects nearly always involve construction of a large dam. That provides flood control, electrical generation, and irrigation water for farms. The disadvantages are often ignored by developing countries. Communities along the river are flooded and must relocate. Excellent fields, orchards and forests may be lost. Fish lose natural habitat such as gravelly areas to lay eggs -- this is especially problematic in the American West. Migratory fish are destroyed because they can't navigate past the dam. The still water becomes warmer that moving water and this can increase unwanted flora (algae, moss, weeds) and unhealthy bacteria. Silt carried by the river deposits in the new lake and slowly fills it up. The sand and silt is essential for healthy beaches -- it is supposed to reach the sea, but ends up stuck behind a dam. 1) displaces many people 2) loss of ariable land 3) salination of irrigated land 4) damages riverine ecologies 5) may damage river and estuary fisheries 6) reduces water flow and thus may imped down river simple irrigation 7) may increase pollution http://en.allexperts.com/q/Geography-1729/2008/5/Multipurpose-River-Valley-Projects-6.htm Positive: 1) provides water for agriculture 2) provides water for human and industrial consumption 3) helps to prevent flooding 4) provides lake fisheries 5) provides infrastructure for many purposes 6) provides electric power or cooling for nuclear power plants 7) improved transportation Negatives: 1) displaces many people 2) destroys prime agricultural lands 3) destroys riverine ecologies and habitat 4) destroys historic and archaeological sites 5) may damage down stream ecologies including estuary fisheries 6) disrupts existing infrastructure 7) can increase the needs for fertilizers and thus increasing the incidents of pollution.