| Srisailam Dam | |
|---|---|
 | |
  Srisailam Dam Location of Srisailam Dam in Andhra Pradesh | |
| Location | Sri Sailam,Nandyal district,Andhra Pradesh,IndiaDomalapenta,Nagarkurnool district,Telangana,India |
| Coordinates | 16°05′13″N78°53′50″E / 16.08694°N 78.89722°E /16.08694; 78.89722 |
| Purpose | Hydroelectric,Irrigation &Water supply |
| Construction began | 1960 |
| Opening date | 1981; 44 years ago (1981) |
| Construction cost | ₹10 billion[citation needed] |
| Owner | Government of Andhra Pradesh |
| Dam and spillways | |
| Type of dam | Gravity &Masonry dam |
| Impounds | Tungabhadra River,Krishna River |
| Height | 145.10 m (476 ft)[1][2] |
| Length | 512 m (1,680 ft) |
| Spillway capacity | 38369m3/s |
| Reservoir | |
| Creates | Srisailam Reservoir (Neelam Sanjeevareddy Sagar) |
| Total capacity | 216tmcft (6.1 km3) |
| Catchment area | 206,040 km2 (79,550 sq mi) |
| Surface area | 616 km2 (238 sq mi) |
| Power Station | |
| Operators | APGENCO(right bank) andTGGENCO(left bank) |
| Turbines | 6 × 150 MW (200,000 hp) reversibleFrancis-type (left bank) 7 × 110 MW (150,000 hp) Francis type (right bank) |
| Installed capacity | 1,670 MW (2,240,000 hp) |
TheSrisailam Dam is agravity dam built on the confluence ofTungabhadra River andKrishna River. Itshydroelectric power station isIndia's 2nd largest by capacity. It is located in theNallamala Hills near the temple townSrisailam.[3]
The dam spans a deep gorge between the districtsNandyal (Andhra Pradesh) andNagarkurnool (Telangana). It has a maximum height of 143 metres (470 ft) and a length of 512 metres (1,680 ft). The reservoir has a surface area of 616 square kilometres (238 sq mi) and a gross storage capacity of 216tmcft (6.1 km3). Theactive storage capacity is 178.74 tmcft (5.061 km3) corresponding to the full reservoir level at 270 metres (885 ft) MSL. The minimum draw-down level of the reservoir is at 215 metres (705 ft)MSL and the correspondingdead storage is 3.42 tmcft (0.097 km3). There are two turbine halls: an underground building on the left bank with six 150 MW (200,000 hp) reversibleFrancis-pump turbines forpumped-storage operation (each turbine can pump 200m3/s) and a semi-underground building on the right bank with seven 110 MW (150,000 hp) Francis-turbine generators.[3]
A tail pond dam/weir located 14 km downstream of Srisailam dam is under advanced stage of construction to hold the water released by the hydro turbines and later pump back into the Srisailam reservoir by operating the turbines in pump mode.[4] The weir portion got breached in November 2015 unable to withstand the normal water release from thehydropower stations.[5] Tail pond weir was completed during the year 2017 and pumping mode operation is being done even when the downstreamNagarjuna Sagar reservoir water level is below 531.5 feet (162 m) MSL. The tail pond has nearly 1 tmcft (0.028 km3) live storage capacity.[6]
The Srisailam project began in 1960, Initially only as a power project. After several delays, the main dam was finally completed twenty years later in 1980 July 26.[citation needed] In the meantime the project was converted into a multipurpose facility with a generating capacity of 770 MW (1,030,000 hp) by its second stage which was completed in 1987.[citation needed] The dam is to provide water for an estimated 2,000 km2 (770 sq mi). Under the right bank branch canal 790 km2 (310 sq mi) in Kurnool and Kadapa districts will have assured irrigation. From the initial modest estimate of₹38.47crore for a power project the total cost of the multipurpose project was estimated to cross₹1000 crore in its enlarged form. The dam has alone cost₹404 crore together with the installation of four generating sets of110 MW each. The right bank branch canal is estimated to cost₹449 crore and the initial investment of₹140 crore has been provided by the World Bank. The projected cost-benefit ratio of the project has been worked out at 1:1.91 at 10% interest on capital outlay.[citation needed]. In 1998 a coffer dam was over topped by flooding. The power house required repairs and did not generate power for a year. On 2 October 2009, Srisailam dam experienced a record inflow which threatened the dam.[7] It was built under the engineering leadership ofKanuri Lakshmana Rao.
Srisailam right main canal (SRMC) is constructed with 44,000ft3/s capacity at Srisailam reservoir level of 269.22 metres (883 ft)MSL to feedVeligodu reservoir (16.95 tmcft; 0.480 km3),Brahmamsagar Reservoir (17.74 tmcft; 0.502 km3), Alaganoor reservoir (2.97 tmcft; 0.084 km3), Gorakallu reservoir (12.44 tmcft; 0.352 km3), Owk reservoir (4.15 tmcft; 0.118 km3),Gandikota Reservoir (26.86 tmcft; 0.761 km3),Mylavaram reservoir (9.98 tmcft; 0.283 km3),Somasila reservoir (78 tmcft; 2.2 km3) andKandeleru reservoir (68 tmcft; 1.9 km3) with nearly 235 tmcft (6.7 km3) total storage capacity.[8] This canal also supplies water toTelugu Ganga project which supplies Krishna river water toChennai city for its drinking purpose.[9] This main canal by feeding water toK. C. Canal, Srisailam right bank canal, Telugu Ganga canal andGaleru Nagari canal irrigates vast area inKurnool,Kadapa,Chittoor andNellore districts.
Handri-Neeva lift canal by drawing water from the Srisailam reservoir, which supplies drinking water in all the districts ofRayalaseema.Veligonda reservoir receives water by gravity through tunnels to irrigate lands in Nellore, Kadapa andPrakasam districts.Kalwakurthy lift irrigation scheme by drawing water from the Srisailam reservoir, supplies irrigation water inMahbubnagar andNalgonda districts
Srisailam left bank canal will receive water by gravity through tunnels to irrigate lands inNalgonda district. Tunnel work is not complete and the required water has been provided to most of the project area by lifting water from the downstream Nagarjuna Sagar reservoir.
Systematic Neglect and absence of diversion of funds is evident in maintenance of the dam and lack of any modernization attempts of the Powerhouse. The officers report a shortage of maintenance staff.[10]
Safety concerns to the 2nd largest Hydroelectric project in the country have been raised over the years[11][12] and have been assessed false subsequently.[13] In 2009, the dam, designed for a maximum flood of 1,900,000 ft3/s, endured a flood of 2,550,000 ft3/s. According to a survey conducted in the summer of 2018, the scouring resulted in the formation of a huge pit in the apron downstream the dam. And a structure protecting the ‘toe’ and foundation of the main dam has weakened. Efforts are not yet made to repair and maintain the dam.[14]
In May 2025, the National Dam Safety Authority (NDSA) inspected the dam and raised concerns about the condition of the Srisailam dam. Over the years, damage has built up around theplunge pool and some key protection works, mostly due to aging and a lack of proper maintenance. Though several expert panels have suggested fixes in the past, the state hasn’t followed through on most of them. NDSA says that ignoring these observations could threaten major structures and cities likeVijayawada andAmaravati.[15]
At present, the initial inflows intoSrisailam reservoir are stored excessively without being used for power generation. The flood water fills the remaining empty Srisailam reservoir quickly and most of the flood water overflows into the downstreamNagarjunasagar reservoir without being used for power generation.[16] The endeavor shall be to fill the Nagarjuna Sagar reservoir fully with the uniform water released through the power generating units.
The existing right bank power station (770 MW) can be converted intopumped storage hydroelectric power (PSHP) to operate in pumping mode when the downstreamNagarjuna Sagar reservoir level is above 560 feet (171 m) MSL. The PSHP can be used for energy storage purposes on daily basis and to transfer Godavari water to the Srisailam reservoir during drought years. Alternately, the tunnel of the existing power station can be used for a new PSHP station to pump water from the Nagarjuna Sagar reservoir to the Srisailam reservoir.
Srisailam reservoir, serving as lower level reservoir, has potential to install nearly 77,000 MWhigh head pumped storage hydroelectric plants on its right side.
| Rivers |  | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Dams and barrages | |||||||||
| Hydro power stations | |||||||||
| Geographical features/regions | |||||||||
| Riparian districts |
| ||||||||
| Cities | |||||||||
| Ores and minerals | |||||||||
| Oil/gas fields | |||||||||
| Industries |
| ||||||||
| Transport | |||||||||
| Related topics | |||||||||
| Other river basins | |||||||||
