VIJAYAWADA: At one stage, it was feared that 1986 flood levels of 36 lakh cusecs will be repeated at the Dowleswaram Barrage, given the increasing flood levels at Bhadrachalam on Thursday. But, floods started receding at Bhadrachalam on Friday and everyone heaved a sigh of relief. The real game-changer has been the lack of heavy inflows from Sabari, a major tributary of the Godavari on its left bank. It merges with Godavari water downstream of Bhadrachalam at Kunavaram.
Engineers of the Water Resources department agree that it was the case. “Had there been more inflows from Sabari when the flood flow was going at 23-24 lakh cusecs at Dowleswaram, even the decrease of flow from Bhandrachalam would not have mattered? The record flood flow of 1986 might have been revisited,” observed a senior official of the Water Resources Department.
Sabari, like Indravati, another major tributary of Godavari, originates from the western slopes of the Eastern Ghats located in Odisha. It travels westwards before turning and travelling south along the Chhattisgarh-Odisha border. Siler, its tributary, merges with it at Konta, the tri-junction boundary of Chhattisgarh, Odisha and Andhra Pradesh. From there it flows south and joins the Godavari river at Kunavaram in Alluri Sitarama Raju district of Andhra Pradesh, downstream of Bhadrachalam town in Telangana.
“The velocity of the flow of Sabari when it merges with the Godavari is high, given the terrain it passes through. Hence, in short order, large volumes of floodwater get dumped into Godavari downstream of Bhadrachalam, which in turn can dictate the flood flow at Polavaram and Dowleswaram,” explained K Haranath, retired superintendent engineer of the Water Resource Department.
However, though there were some heavy rains in the catchment areas of Sabari and Indravati, the duration was less and the volume of water drained into the Godavari from Sabari was less. Another factor was, there were fewer heavy rains in the Rampachodavaram region during the unprecedented floods.
“Most importantly, it was timing. The copious inflows from Sabari to the Godavari, when the flood discharge rate was 23-24 lakh cusecs at Dowleswaram is a different concept altogether, when compared to copious inflows from Sabari to Godavari when the discharge level at Dowleswaram was below 20 lakh. At low discharge levels at Dowleswaram, high discharge rate from Sabari to the Godavari is manageable,” a senior engineer of the department told The New Indian Express.