Thankyou for the report by APWRDC. Impact of Two aspects are not considered in the presentation.
1)Effect of failure of Sunkesula barrage's earth dam: Since this barrage is very close to Srisailam reservoir back waters, the water deluge by this earth dam burst has substantially increased the peak flood flows in downstream Srisailam reservoir. That means a meadium barrage's earth bank failure can jeopardise all the down stream mojor dams during monsoon floods. The earth bank burst has washed away few villages down stream of the barrage causing hundreds of deaths. This aspect is not studied in the presentation by giving hourly data of Sunkesula barrage given similar to srisailam, Nagarjunasagar, etc. Whether any action is intiated on the contractor & engineers associated in the construction of the earth dam of Sunkesula barrage? Had the srisailam dam yeided to floods, the water deluge would have wiped out atlease 10 million people in the downstream particularly in Khammam, Krishna, Guntur and west Godavari districts.
2) Effect of not releasing full capacity flood to the nagarguna sagar reservoir from Srisailam dam by opening all the gates fully till the Srisailam power houses are flooded by flood waters:Left bank power house got marrooned in 1998 floods due to the reson that a coffer dam to protect the power house was not constructed up to the planned height undermining flood intensity.At that time, Rs 1000 crores were spent to repair the power generating units and the power station could not generate power for one year though water is available in the reservoir. What are the reasons of power house flooding during these record breaking floods!During the peak flood in flow hours the down stream Nagarjuna Sagar dam was not above its FRL (FRL is achieved in most of the years). More flood could have been let down stream by opening all 12 gates fully but not done till the power houses got marrooned. This indicates that flood release from the dam is controlled to prevent power house flooding by controlling tail water level of the dam. This can be due to following reasons:
a) the coffer dam of the power house may not be constructed even after 1998 floods experiance.
b)The maintenance planning of semi under ground hydro units (7 nos) are not properly planned and organised such that not to extend these activities in to the monsoon season. It can happen that the water sealing barriers /flooring are removed between the hydro turbine and the generator to prevent water entry in to generator area. Other wise it is not possible for the flood waters to flood the semi under ground power house totally

The report did not explain the resons how the water entered in to the power houses and the measures taken to prevent water flooding on hourly basis. This repeated water flooding of the power house in a decade has incurred heavy expenditure for repair and loss of substantial no cost power generation. When hydro units are working at 30% LF, their O&M planning should be such that their power generation reliabilty is more than 95% to maximise power generation as per water availability. They shoud not break down when water is available to generate power.
It is very good solution that all the run off inflows in Srisailam reservoir let in to the downstream Nagarjunasagar reservoir promptly through power units keeping the reservoir level low such that it can accomodate more flood waters to reduce peak flood releases from the dam. This would optimise the power generation during good monsoons and achieve better flood management.