Flooding is a reality for many parts of the world. Many regions are confronted with rising sea levels and drought, with effects on plant species as well as local ecosystems. Hydropower plants on the Himalayan region are frequently confronted with these problems in areas where seasonal floods may occur, especially during the monsoon season, from precipitation runoff and melting ice caps. A hydropower plant can be permanently damaged or destroyed by heavy rainfall; its support structure is also seriously damaged by such events. There are some rare but severe flooding cases where hydropower plants on the Himalayan regions were wiped out by such floods, with the hydropower system becoming structurally unsound and unfit for further use.
In such occasions, when hydropower projects are threatened by floods, the risk level to residents and businesses rises sharply, with much needed hydropower capacity removed from the system altogether. A sudden large hydropower project at a remote area can completely wipe out a regional economy, with the loss of employment and business opportunities. Floods caused by natural disasters may not have an immediate negative effect on hydropower projects at present, but a long term impact due to disruption to regional ecosystems and breeding grounds for disease will affect people living around the water sources.
India is one of the main users of hydropower. Some of the largest hydropower plants in the world are located in India, in places like the Western Ghats in Uttaranchal, the Central Indian states of Madhya Pradesh and Orissa, and the Western Ghats in Kerala. In some of these hydropower zones, a variety of species of both plant and animal life co-exist in relative harmony, especially in the tiger reserves in India. If the habitats of the plant and animal species were to disappear, the hydropower would surely be wiped out too. For this reason, hydropower projects are often designed in such a way as to minimize environmental harm to the environment and its indigenous inhabitants. A prime example is in the Western Ghats where hydropower channels are built deep into the riverbed below the plants so that runoff from the plant cannot infiltrate the soil.
This same principle of minimal environmental impact is used in other hydropower projects around the world. Hydropower plants are also designed to withstand local weather and climatic changes. For instance, in the upper reaches of the Western Ghats, where there is generally a large range in altitude, hydropower stations are set far apart to weather any harsh weather conditions. Similarly, hydropower plants are placed in areas which have a regular influx of rainfall and are thus most susceptible to the heavy downpour of monsoon rains. This prevents the damage caused by excessive rainfall on the hydropower infrastructure.
Why flooding raises alarm over the bearing of hydropower plants on the flood plains? When rain water comes down from the slopes and floods the fields immense hydroelectric power is generated. However, this creates a problem. The water, being high in the water table, has to pass through many small canals which are low in this water table. Once it arrives at the hydropower dam, the water slowly dries up and the electricity produced is not sufficient for the needs of the local people. This, combined with the evaporation of the standing water in the valleys, raises concerns about the impact of the hydropower plant on the environment of the river and the impact of river flood on the environment of the surrounding areas.
This problem can be solved by the implementation of a number of measures to reduce or mitigate the flooding which causes significant damage to the hydropower plants and to the areas around them. An integrated eco-friendly drainage system can be installed to reduce the amount of runoff from the area. This will not only help prevent flooding, but will also help to capture rainfall so that it does not evaporate into the river and thus contribute to the evaporation of the water table. The use of permeable membranes that allow the water to pass freely so that it is recovered by the rivers and canals without causing any harm to the environment will also help prevent the flooding.