Every system, natural or man made has advantages and disadvantages of its own. Depending on the extent of disadvantage the system is exploited further or discarded. Though hydro power has a number of advantages, it also has some disadvantages. Some of the problems faced during the generation of hydroelectricity are given below:
ALTERATION OF SURROUNDING- Generation of hydroelectricity demands a vast area of land to construct dams and the hydro electric power station. To store water in dams, large area has to be evacuated first and then water is let in. This is not an easy job, because such vast barren land is not available in most parts of the world. They are occupied by human beings, plants and animals. All these have to displaced to construct a dam, and trees have to be felled. This causes a large damage to all the flora and fauna of the area, bringing about a destruction of the ecological balance of the place. The food chains of many organisms, micro and macro are also disturbed. This causes serious trouble to these organisms, sometimes causing the extinction of certain species altogether.
CHANGE IN PHYSICAL CHARACTER OF WATER- in the process of generation of hydro power water is used to rotate large turbines, in the process the water is also circulated along with the turbine. During such circulation a number of physical changes occur to the water such as
The rise of temperature of water- the temperature of water increases thus bringing about loss of water due to vaporisation. Decrease in oxygen content- large amount of water is present dissolved in the water. This oxygen is used by the aquatic organisms for their breathing process. Due to rotation the oxygen reduces bringing about reduction of biological oxygen demand for the aquatic organisms. This in turn reduces the number of flora and fauna present in the water. Rotation of water also changes the phosphorus and nitrogen content of water. The carbon content responsible for the temperature maintenance of water increases; this may increase the temperature of the water.
DAMAGE TO AQUATIC LIFE – When dams are constructed in the path of water the life of many plant and animal life in the water is damaged. This is evident in the case of salmon fish. Salmon fish generally migrate upstream to spawn, but due to dam construction they are hindered from travelling upstream. This reduces the population of salmon fish, which in turn affects the population of other animals feeding on salmon fish.
METHANE PRODUCTION – New researches have found that when water is stagnant for long periods of time the plant present in them start decomposing. This decomposition process releases methane, which is a green house gas and has the property of increasing the temperature of Earth.
