How Tungabhadra dam gate was swept away, why farmers are fearful

• A flood alert has been sounded downstream of the Tungabhadra dam in Karnataka’s Koppal district
• This was due to one of the 33 crest gates of the massive stone masonry dam across the Tungabhadra river being washed away.

How the gate broke

• The dam has 33 ‘vertical lift’ type gates that move on rollers embedded in the masonry. The gates are operated from an overhead bridge.
• The crest (or spillway) gate failed after a link in the chain used to operate it broke.
• The force of the water in the dam swept the 60-foot-by-20-foot gate, weighing around 20 tonnes, some 500 ft away
• Local sources said welding was carried out on the chain links of the spillway gates to strengthen them 3-4 years ago.

Tungabhadra River

• The Tungabhadra, which is formed at the confluence near Shimoga of two streams, Tunga and Bhadra, that rise in the Western Ghats, flows into the Krishna at Sangamaleshwaram in Andhra Pradesh.
• The river, which forms part of the boundary between Karnataka and Andhra Pradesh, has a total catchment area of almost 70,000 sq km.
• The Tungabhadra reservoir sprawls over an area of 378 sq km primarily in Karnataka’s Vijayanagar district.
• It is one of the major reservoirs in South India that supplies water for irrigation and industrial use, as well as drinking water to Karnataka and Andhra Pradesh.
• The dam was first conceived of in 1860 to mitigate the impact of recurrent famine in Rayalaseema.
• Construction was begun by the erstwhile governments of Hyderabad and Madras in 1945, and the project was completed in 1953.
• The Tungabhadra Board was established by a presidential order in 1953.
• The Board currently has a chairman appointed by the Union government, and four members, representing the Union government and the states of Karnataka, Andhra Pradesh, and Telangana.