VIJAYAWADA: On August 31, as per regular practice, the irrigation department officials notified about the rise in floodwater level of the Budameru and the Krishna river in the WhatsApp groups of the administration at mandal and district levels.
However, the alert was about the increasing floodwater and operating the Velagaleru Head Regulator gates, and they failed to anticipate that heavy inflows more than the capacity of Budameru Diversion Channel would result in breaches, leading to the Budameru original course in the night, which in a matter of a few hours flooded half of Vijayawada, which was lashed by torrential downpour since Friday night.
A senior official said normally for the rivers and streamlets, IMD alerts from the CWC are taken as warnings, and based on the rainfall and floods in the catchment areas upstream are taken into consideration to calculate the time the flood would reach the Prakasam Barrage or other places and accordingly the revenue department will take informed decisions.
“However, sometimes flash floods occur due to sudden rains in upland and hilly areas, which is difficult to anticipate. In the case of rivulets like Budameru, the flood assessment is based on IMD forecast and local rainfall. On August 31, a flash flood occurred upstream of head regulator, with several tanks upstream breached following heavy rains in their catchment areas. Even in the influence sphere of Budameru like G Konduru, Mylavaram and A Konduru, there were flash floods in the streams feeding Budameru,” he explained.
The flash flood was not anticipated though an increase in the floodwater level of up to 30,000 cusecs was anticipated and the officials concerned were alerted to lifting the gates of regulator. However, the floodwater level beyond the capacity of the Budameru Diversion Channel breached the bund, and the floodwater flowed back into the original course of the rivulet. When Budameru flooded in 1964, submerging northern parts of Vijayawada, it was recorded that 24,000 cusecs of water was discharged upstream of Velagaleru. However, the flood plains of Budameru had only fields and a few minor settlements at that time.
To prevent flooding in the future, the head regulator was constructed on Budameru at Velagaleru village with a capacity of 7,500 cusecs, and the original course of Budameru was retained at 16,500 cusecs. In 1991-92, the capacity of diversion channel was raised to 15,000 cusecs, and original course was left with 9,500 cusecs. With rapid urbanisation, all the flood plains of Budameru were occupied and even the flood banks were encroached upon. The discharge capacity of Budameru’s original course that passes through Vijayawada was reduced to less than 3,000 cusecs.
“There is an urgent need to implement the proposed increase in discharge capacity of 15,000 cusecs to flood-proof the city,” an irrigation expert said.
