Andhra Pradesh Water Resources Department officials have expedited the excavation work of the approach channel to divert the flow of the Godavari floodwaters towards the Polavaram project spillway. This channel will be completed after another one crore cubic meters of earthworks are finished.
The DDRP (Dam Design Review Panel) approved the design on the 23rd of this month. and authorities are taking all steps to complete the work by May deadline which was set by the government. As of now, water will be released for Rabi crops in the Godavari Delta till the 31st of this month. The gaps left on either side of the upper cofferdams will be filled after this.
While in the Godavari Delta region water will be released for Kharif crops in the first week of June, officials said.
Since the Godavari river starts receiving flood waters from June itself, authorities have taken steps to complete the Spillway and Spill Channel works before that time. For this, the approach channel must be completed to divert the flow towards the spillway.
However, the DDRP did not approve the design of the approach channel, for which the earthworks could not be carried out. Now with the approval, the excavation works will be completed faster. Initially, it was estimated that the approach channel would have to be dug at a length of 450 metres and 550 metres in width and an estimated 50 lakh cubic metres of soil needed to be excavated for this purpose.
Scientists at the Central Water and Power Research Station (CWPRS) in Pune were entrusted the task to dig an approach channel to easily divert the 50 lakh cusecs of floodwaters to the spillway to the Godavari by the Central and State governments.
CWPRS scientists have built a 3-D prototype Polavaram Project over an acre on the PWPRS premises. They conducted research on the pumping of water toward the spill at the same pressure as when the floodwaters reach 100 million to 50 million cusecs.
Based on the findings, the approach channel from the river was initially widened to 550 metres. After that, the width of the channel was increased to 600, 650, 700, 750, 800, 850, 900, 950 metres accordingly.
It was concluded that by digging with a width of one thousand meters near the spillway, floodwaters could be easily released downstream. DDRP who studied the report given by CWPRS gave their consent for the findings in the report and approved the design. It is estimated that about one crore cubic meters of soil will have to be excavated in the approach channel in light of the new design change.
The excavation of the approach channel has to be completed by May this year to provide water for Kharif crop cultivation in the Godavari Delta region or to release the floodwaters easily downstream. The earthworks started on the 24th of this month.
Authorities expressed confidence that since they planned to dig 1.50 lakh to 2 lakh cubic meters of soil per day they would be able to complete the work ahead of schedule. By this, the floodwaters released in June would be diverted towards the spillway.
This would pave for the continuation of the works on the earth-cum-rockfill dam (ECRF dam) between the cofferdams without any hindrance and ensuring completion of the Polavaram Project, officials said.