Situation of Indian Dams

Situation of Indian Dams

News: According to a new Comptroller and Auditor General of India (CAG) report, Gandhi Sagar Dam on Chambal River (Madhya Pradesh) is in need of immediate repair.Absence of regular checks, non-functional instruments and choked drains are the major problems plaguing the dam for years.

About:
• India is ranked third in the world in terms of building large dams.Of the over 5,200 large dams built so far, about 1,100 large dams have already reached 50 years of age and some are older than 120 years.
• The number of such dams will increase to 4,400 by 2050.This means that 80% of the nation’s large dams face the prospect of becoming obsolete as they will be 50 years to over 150 years old.
• The situation with hundreds of thousands of medium and minor dams is even more dangerous as their shelf life is even lower than that of large dams.
• Krishna Raja Sagar dam was built in 1931 and is now 90 years old. Similarly, Mettur dam was constructed in 1934 and is now 87 years old. Both these reservoirs are located in the water scarce Cauvery river basin.

Issues India’s Dams:
• Indian dams are very old and built according to the rainfall pattern of the past decades. Erratic rainfall in recent years has left them vulnerable.But the government is equipping the dams with information systems like rainfall alerts, flood alerts, and preparing emergency action plans to avoid all sorts of mishaps.
• As dams age, soil replaces the water in the reservoirs. Therefore, the storage capacity cannot be claimed to be the same as it was in the 1900s and 1950s.The storage space in Indian reservoirs is receding at a rate faster than anticipated.
• Studies show that the design of many of India’s reservoirs is flawed.Indian reservoirs are designed with a poor understanding of sedimentation science.The designs underestimate the rate of siltation and overestimate live storage capacity created.
• It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or permanent) of fine sediments on bottoms where they are undesirable.

Consequences:
• When soil replaces the water in reservoirs, supply gets choked. In this case, the cropped area may begin receiving less and less water as time progresses.
• As a result, the net sown water area either shrink in size or depends on rains or groundwater, which is over-exploited.As crop yield may get affected severely, it would disrupt the farmer’s income.
• Moreover, water is a crucial factor for crop yield and credit, crop insurance, and investment.
• The flawed siltation rates reinforce the argument that the designed flood cushion within several reservoirs across many river basins may have already depleted substantially, due to which floods have become more frequent downstream of dams.

Way forward:
• Ageing dams can serve as a cause of concern for people living in the areas nearby.Safety of dams is also important for safeguarding the huge public investment in this critical physical infrastructure, as also, for ensuring continuity of benefits derived from the dam projects and national water security.
• Safety of dams is also important in the emerging scenario of India’s water crisis, linked with its growing population, as also the climate change.