Methods to harness huge dead storage • The left and right bank canals sill level is fixed at
MSL to supply irrigation water to two million acres. The unutilized storage capacity is nearly 180
TMC below the canals sill/bed level. Nagarjuna Sagar reservoir also meets the Krishna delta water requirements to the extent of 80 TMC by letting water downstream into the river. Nearly is irrigated under Krishna Delta Canals. There is a possibility to utilize most of this idle dead storage capacity to store the river flood water further and to use as carry over storage. Nearly 150 TMC idle storage up to MSL, can be used leaving 30 TMC for silt settlement. This is possible by installing Water Powered Pump (WPP) units at the base of the dam. • It is technically feasible to generate power from the existing hydro turbines from the lower head (75 to 50 meters) by running the turbines below the rated speed. However, major modifications of generators are to be done for running below the rated speed and improve the power generation efficiency. • The sill level of the right bank canal powerhouse (3 x 30 MW) is at MSL. It is possible to draw water from the dead storage by tapping water from the penstocks to feed water to a pump house (3 x 15 MW) located on the left side of the powerhouse. The pump house will have three pump sets each of 5000 cusecs flow capacity to feed into the NS main right bank canal. Power generation from the 90 MW powerhouse is no way affected since its units can only operate when the reservoir level is above 540 ft MSL and the pumping units need to operate below the 508 ft MSL to draw water from the dead storage. Thus nearly 50 TMC water can be utilized during the drought years. The water supply is nearly 50% of the total city water requirement. This water pumping scheme is part of
Alimineti Madhava Reddy lift irrigation project with its foreshore pumping station at Puttamgandi which has nearly 2400 cusecs pumping capacity. The water supply to the Hyderabad city is nearly 15% of its total capacity. The approach channel from the reservoir to the Puttamgandi pump house (PH) is located at where the Bhimanapalli Vagu tributary is joining the Krishna river. The minimum draw down level (MDDL) of the PH is MSL below which water can not be pumped from NS reservoir. The reliability / dependability of the PH for supplying assured water supply to Hyderabad city, is not adequate due to meagre inflows into the NS reservoir in some years and the need to deplete the NS reservoir water below 502 ft MSL for other purposes. In these circumstances, adequate water is to be stored above the 502 ft MSL to maintain 100% assured water source without depending totally on NS reservoir. This is possible by constructing a balancing reservoir by separating some area of the NS reservoir with a new dam across the Bhimanapalli Vagu tributary at just upstream of the Puttamgandi PH approach channel. This new dam with FRL MSL, would not submerge any additional area other than the area already submerged by the NS reservoir. The water inflows from the Bhimanapalli Vagu tributary joining the NS reservoir are first impounded by the new dam and if found excess over flows into the downstream NS reservoir. This new balancing reservoir's live capacity is nearly 6 Tmcft above the 502 ft MDDL which is equal to six months water supply to the Hyderabad city. This reservoir would have provision to receive water from the Puttamgandi PH when inflows from the Bhimanapalli Vagu tributary is not satisfactory and water is at adequate level in NS reservoir during monsoon months. When water level of NS reservoir goes below the 502 ft MSL, water is fed to the Puttamgandi PH approach channel from the new balancing reservoir for pumping water needs of Hyderabad city. The cost of this new dam project would be nearly 1.5 billion rupees only which will provide 100% assured water supply to the Hyderabad city without depending on the water availability from NS reservoir during the non monsoon months and drought years.
Godavari water transfer via Nagarjuna Sagar left canal to Krishna River The Nagarjuna Sagar left canal supplies nearly 130 TMC of water for irrigation needs in Telangana and Andhra Pradesh states. This is a
contour gravity canal with gradual downward gradient (≃ 1:10,000) along the water flow direction. This canal can be used for transferring nearly 80 TMC
Godavari River water into the Nagarjuna Sagar reservoir in addition to supplying the Godavari water under its entire command area. Thus a total of 210 TMC of Godavari water can be used in the Krishna basin of Telangana state from
Srisailam and
Jurala reservoirs for the new projects with 100% water dependability. Godavari water transferred into the Nagarjuna Sagar reservoir and Krishna main river can also be used for the proposed Palamuru lift irrigation and Nakkalagandi lift irrigation schemes in Telangana. This is possible by re-engineering of the left canal to reverse its water flow direction from the location (near ) where Godavari water would be pumped into this canal. The canal embankments would be raised to facilitate flow reversing towards Nagarjuna Sagar reservoir and intermediate pumping stations (with low head & high flow concrete volute pumps) would be installed near the
Paleru balancing reservoir, Pedda Devulapalli balancing reservoir, left canal head regulator on the rim of Nagarjuna Sagar reservoir and the existing major
aqueducts across Halia,
Musi and
Munneru tributaries. The cost of this canal redesigning and the associated pump houses would be one third of a new scheme to transfer Godavari River water into Nagarjuna Sagar reservoir at its FRL
MSL with least possible total pumping head. The above re-engineering of the canal is similar to modifications carried out to reverse the water flow of ancient
Grand Canal under Eastern Route project of
South to North Water Transfer in China. == Nearest Cities ==