Coffer dam height to withstand floods: Andhra Pradesh

Rajahmundry: Following severe criticism from Opposition parties and experts on enhancement of coffer dam height to plus 41 metres from the proposed plus 31 metres, who believe that the move was aimed to delay the construction of the earth-cum-rock-fill dam of Polavaram irrigation project, the state government has clarified that it was the Design Review Committee (DRC) which enhanced the dam’s height so as to withstand high floods in the Godavari river.

Coffer dam is a kind of temporary structure constructed across the Godavari river to stop the water flow to construct earth-cum-rock-fill dam of the Polavaram project. Though the coffer dam was initially planned at a height of plus 31 metres to check nearly 25 lakh cusecs of water in the river, the Design Review Committee consisting of experts from Central Water Commission and other agencies enhanced its height to plus 41 metres to enable it to withstand pressure of nearly 28 lakh cusecs of water in the river. DRC had carried out a series of studies and even studied model coffer dams before arriving at the decision to enhance its height.

Water resources authorities say that a spillway with 48 gates is also being constructed. If the river witnesses heavy inflow of water, they will open the gates and allow the water to flow to ensure that the coffer dam is not washed away.

In case the inflow of water into the river is on expected lines, they will open two gates and allow nearly 11,000 cusecs of water into the spillway and from there the water will flow by gravity into the Polavaram Right Ma-in Canal to supply water to its command area and allow the water to flow fu-rther even to the Krishna delta, based on need.

Polavaram project superintending engineer V.S. Ramesh Babu said, “The DRC has taken the decision to enhance the height of the coffer dam to sustain water inflow into the river of up to 28,000 cusecs of water. If the height of the dam is not enhanced and there is heavy inflow of water into the river during rainy season, we have to stop construction of the earth-cum-rock-fill dam and this will further delay completion of execution of the project.”

Retired irrigation engineer K. Haranath said, “Construction of coffer dam to stop inflow of wa-ter in the river for constr-uction of earth-cum-ro-ck-fill dam is a common phenomenon. But in case of unprecedented flood in the river, no coffer dam can withstand it.”

Following severe criticism from Opposition parties and experts on enhancement of coffer dam height to plus 41 metres from the proposed plus 31 metres, who believe that the move was aimed to delay the construction of the earth-cum-rock-fill dam of Polavaram irrigation project, the state government has clarified that it was the Design Review Committee (DRC) which enhanced the dam’s height so as to withstand high floods in the Godavari river.

Coffer dam is a kind of temporary structure constructed across the Godavari river to stop the water flow to construct earth-cum-rock-fill dam of the Polavaram project. Though the coffer dam was initially planned at a height of plus 31 metres to check nearly 25 lakh cusecs of water in the river, the Design Review Committee consisting of experts from Central Water Commission and other agencies enhanced its height to plus 41 metres to enable it to withstand pressure of nearly 28 lakh cusecs of water in the river. DRC had carried out a series of studies and even studied model coffer dams before arriving at the decision to enhance its height.

Water resources authorities say that a spillway with 48 gates is also being constructed. If the river witnesses heavy inflow of water, they will open the gates and allow the water to flow to ensure that the coffer dam is not washed away.
In case the inflow of water into the river is on expected lines, they will open two gates and allow nearly 11,000 cusecs of water into the spillway and from there the water will flow by gravity into the Polavaram Right Ma-in Canal to supply water to its command area and allow the water to flow further even to the Krishna delta, based on need.

Polavaram project superintending engineer V.S. Ramesh Babu said, “The DRC has taken the decision to enhance the height of the coffer dam to sustain water inflow into the river of up to 28,000 cusecs of water. If the height of the dam is not enhanced and there is heavy inflow of water into the river during rainy season, we have to stop construction of the earth-cum-rock-fill dam and this will further delay completion of execution of the project.”

Retired irrigation engineer K. Haranath said, “Construction of coffer dam to stop inflow of water in the river for construction of earth-cum-ro-ck-fill dam is a common phenomenon. But in case of unprecedented flood in the river, no coffer dam can withstand it.”