Vijayawada: Marking a major milestone in the execution of the prestigious multipurpose Polavaram irrigation project, works to divert Godavari river from right to left canal from its main course by about 6.5 km to rejoin it again have commenced. The works will involve closure of the upstream cofferdam in a phased manner at Angaluru village in Devipatnam mandal in East Godavari district.
Water resources authorities say that for the construction of earth-cum-rock-fill dam of the project, cofferdams both upstream and downstream need to be built so that the dam will come up in between them.
The upstream cofferdam will be raised to a height of 42.5 metres and spread across the river bed for a length of nearly 2,480 metres. The entire length of cofferdam is divided into four reaches or gaps and these gaps which facilitate flow of water in its main course, are being filled up at present one by one. So far, 7.56 lakh cubic metres of rock filling works in the gaps have been taken up.
Reach-1 started from zero point to 480 metres across the river and its present height is 35 metres. Reach-2, spread from 480 metres to 1,700 metres length, is raised to 38 metres. The heights of Reach-3 spread from 1,700 metres to 2,100 metres and also Reach-4, spread from 2,100 metres to 2,480, are being raised to 34 metres. By the end of June, the height of all four reaches will be raised to 38 metres and by the end of July, it will be 42.5 metres.
In a first-of-its-kind diversion of the natural course of Godavari river by raising the upstream cofferdam, water will be routed through an approach channel to the spillway by lifting the crest gates to the pilot channel. The water will rejoin the main course of the original river downstream towards Dowleswaram near Rajahmundry. The whole diversion will be for a distance of about 6.5 km.
As the Godavari river is expected to witness floods with the onset of south-west monsoon in June, works are being expedited to fill up the gaps of upstream cofferdam so that water flow will be stopped and released through spillway by lifting the radial crest gates. Out of 42 crest gates fixed at a height of 42.75 metres, 21 gates are lifted to a height at 40 metres at present to facilitate the flow of flood water from the river downstream. The works to raise the remaining 21 crest gates will be completed by the first or second week of June.
Similarly, the cofferdam downstream will also be raised to a height of 30 metres. It has reached 22 metres and the works would be over by July.
Following a direction from Chief Minister Y.S. Jagan Mohan Reddy to complete the Polavaram project by the end of 2021 and ensure supply of water for irrigation for the next kharif, the project executing agency MEIL has increased the pace of works. Polavaram project chief engineer B. Sudhakar Babu said, “We have started filling up the gaps of upper cofferdam in a phased manner to divert river water from the main course through spillway back to its original course downstream by the time the river witnesses floods, to facilitate construction of ECRF as per direction from Irrigation Advisory Board to divert river water by June 15. However, as some part of the diaphragm wall suffered damage, we will take up its repair at first and later take up execution of lower cofferdam and ECRF to complete whole project works as per schedule.”
