Nagarjuna Sagar tail pond is a multipurpose reservoir located 21 km downstream from the Nagarjuna Sagar Dam across the Krishna River near Satrasala in Nalgonda district, India. Its gross water storage capacity is 6 Tmcft.[1] The reservoir water spread area extends up to the toe of the Nagarjuna Sagar dam. The project was completed by July 2014.[2]
810 MW peaking power station at the toe of Nagarjuna Sagar dam
Hydro electricity generation
Two units of 25 MW each hydro power generation units were commissioned in the year 2017 by APGENCO to utilize the head available across the dam from the river flood water and the water released to Prakasam Barrage requirements.[3]
Peaking power generation
Presently, the 700 MW reversible hydro turbines (7 x 100 MW) located at the toe of Nagarjuna Sagar Dam are unable to operate in pumping mode due to non availability of tail pond for storing the released water during the power generation mode. With the completion of tail pond, surplus electricity from the electricity grid would be used for pumping the water back to the Nagarjuna Sagar reservoir and recycled for meeting peaking load on daily basis. Thus surplus electricity is consumed when it is available and used to meet the peak electricity requirements without letting the water out of the Nagarjuna Sagar tail pond. 700 MW peaking power for eight hours duration can be met from the one Tmcft of live storage water capacity available in the tail pond.
Dummugudem to Nagarjuna Sagar tail pond link canal is entirely located in Telangana region and needs to be routed through high lands which necessitate more pumping head.[4] An alternative link canal to Nagarjuna Sagar tail pond from Polavaram dam is also economically feasible to transfer Godavari water. This link canal passes entirely through the coastal Andhra Pradesh region only.
The Rajolibanda barrage is not receiving adequate continuous flows due to excessive water utilization in its catchment area in Karnataka. The lower Tungabhadra basin badly needs water augmentation from the adjacent Krishna river. This is achieved with a 20 km long tunnel from Narayanpur reservoir to the Maski nala reservoir / tank situated at 475 m MSL for drawing nearly 250 tmcft Krishna river water.[5] It would also provide additional water to bring more area under irrigation in uplands of Raichur & Mahboobnagar districts. Reliable Krishna river water can be supplied instead of unreliable Tungabhadra river water to the existing Tungabhadra Left bank canal in Raichur district, existing Tungabhadra right bank low level canal, the existing Rajolibanda left bank canal and the existing 150 years old K. C. Canal. Thus substantial Tungabhadra reservoir water would be saved for utilization in upstream new projects and reliable Krishna river water supply is ensured to existing projects.
A new barrage (FRL 349 m MSL) across the Krishna river just downstream of Bhima river confluence point on the common border of Karnataka and Andhra Pradesh states (near 16°24′25″N77°17′21″E / 16.40694°N 77.28917°E / 16.40694; 77.28917), can also be taken up to supply Krishna river water by lift irrigation to the westernmost parts of Mahbubnagar district and high lands lying east of Bhima river in Karnataka.
Ultimately, 500 tmcft water is to be transferred annually from the Godavari river to this pond for meeting various water needs in Andhra Pradesh. Thus Nagarjuna Sagar tail pond will play pivotal role to put to use the water from the Godavari River in all regions of the Andhra Pradesh state.
