Water levels are already at 18 feet; the additional water will cause an raise these by another 30 feet. Also, Prakasam Barrage has not received 10 lakh cusecs of water in one go for decades now. The Krishna Bund too is weak at several points and could breach causing flash floods.
A lakh and a half people have to be evacuated from the area before this happens. Another 1.3 lakh people from nearby Vijaywada and 45,000 from Guntur also need to be evacuated.
The administration had no choice but to release the waters to keep two critical dams out of danger - the Nagarjuna Sagar and Srisailam.
Rescue focus has shifted from marooned Kurnool to these downstream areas, as they are likely to face the full fury of the engorged and overflowing Tungabhadra and Krishna rivers.
Three districts in the state are most affected - Krishna, Godvari and Kurnool. In Kurnool, floods have left 33 people dead, though the official toll appears to be far below the actual figure.
Trafficwise, National Highway 18 has been breached, and both rail and road movement between Kurnool and Chennai is disrupted.