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|Title:||GENERAL EFFECTS OF BUILDING RESERVOIR ON THE ENVIRONMENT|
|Authors:||Prasad, Raj Kishore|
|Keywords:||WATER RESOURCES DEVELOPMENT AND MANAGEMENT;BUILDING RESERVOIR;ENVIRONMENT;RESERVOIRS|
|Abstract:||When water is impounded in the reservoir, changes occur in chemical composition and thus in water quality. Stream flow, seasonal pattern and stratification are the major influence because of sediments which contain inorganic, organic matters and other pollutants. Various forms of organic nitrogen in lake sediments is due to decaying algae, plankton, aquatic plants, micro-organisms and benthic fauna. Decomposing organic materials exerts on oxygen demand and contribute colour and odour problem as well as it is toxic and repelling to fish. The seasonal patterns and waste effluents of the streamflow and biological uptake activity influence the con-centration of nutrients in which nitrate-nitrogen and phos-phorus are the responsible for the productivity. other minerals • like chloride, sulphkke, etc. also goes higher. Stratification caused by density and temperature variation with depths. Enrichment of decaying algae from eplimnion enhance the deo ygene.tion rate of bottom layer and hypolimnion becomes anaerobic. Thermal pollution by some industry and electric generating plants raise water tempera-ture, and plants and animals are affected. Rise in water temperature deplete oxygen as well as density. 'Hexadecanol' used as evaporation suppression has no effect on ecology of reservoir. The damming caused aggradation and degradation. Low dissolved oxygen of hypolimnion water releases affects aquatic life downstream. Generally, increase in nutrients followed by an increa-sed biological productivity hasten the extinction of body of water. Several lakes having same nutrients differ o in biological productivity due to morphological factors which affects distribution and availability of nutrients. When the ratio of nitrogen to phosphorus is less than 7:1 blue-green • variety of planktonic algae are favoured and the lakes become eutrophic which indicate a der l.ed environment. Water level fluctuation also cause change in bottom organisms. Also bac-terial concentration reduces due to longer detention time in oligotrophic lakes. The fish life depends on the oxygen concentration and temperature of reservoir water. The minimum level of DO. need-ed for survival is 1.0 mg/1 to 3.0 mg/i but greater concen-tration is needed for activity, growth and reproduction. Stratification accompanied by depleted DO in hypolimnion restrict the vertical movement of fish. Cold water fish may be confined to the narrow part of thermocline by lethal eplimnetic temperature and , an axonoxic hypolimnion. Some mineral concentration especially zinc and copper, constitute an important form of water pollution, are also lethal to fish life. Water flowing over a spillway beoomes aerated after plunging become supersaturated with nitrogen which enters the blood and tissue through the gills of the fish. Under low water pressure or higher temperature, it try to return to gaseous state and produce bubbles which block the blood vessels of the fish and become lethal. De stratification of deep lakes and shallow lakes would benefit fish population due to increased available habitat. The decline in fishery most often occurring due to change in the balance between the fish species. Mosquito-borne Malaria and Bilharzia are the impor-tant diseases related to impounding of water. Their habitats are reservoir shoreline, floating vegetation, irrigated land with dense crops, poorly contoured irrigation canal etc. A regular weekly variation of reservoir levels of 0.3 m have found suitable for the disruption of life cycle of mosquito, larvae and their food supply. The inundation by reservoirs have serious effects on archeological and historical areas. Reservoir clearing or deforestation affects the reservoir etiology and water quality. Wild life are also affected due to loss of feeding areas, loss of habitat and limitation of mobility. Access to water becomes problem when reservoir banks are used by people. Flooding peats have a great problem in Koka reservoir. Reservoir also change the habitat and food of water fowls from which they are habitual. Due to this some migrates to other places and some may migrate to its new places. Impounding of water in reservoir is responsible for increase in number of events of earthquakes with their centre below or near the lakes. But some investigators also opined due to imbalance in hydrostatic pressure resulting in slip-page along fault plane cause triggering effect. Noise damage to hearing ar other effects amongst work force and need attention. At normal behaviour, digestive troubles, imbalance in body organs, heart imbalance, peri-pherial circulation etc. Generally air and water pollution have no effects on man during construction. Displaced persons have to chaige their occupation due to delayed payment and rise of price of farm land. But their overall life conditions have been improved. The various uses of water include some, which bring about both quantitative and qualitative problems all over the world. Reservoir also affects the climate of the areas. Aesthetics offers embedment of dam in nature's sites in beautiful rural landscapes and its reservoirs provide various recreational activities and attract visitors in increasing number especially form neighbourhood of crowded industrial areas.|
|Research Supervisor/ Guide:||Nigam, P. S.|
|Appears in Collections:||MASTERS' DISSERTATIONS (WRDM)|
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