Hyderabad: A huge loss of water flow has been observed on a 52-km stretch between Koida and Polavaram in Godavari river in a study conducted by Kaila Sreenadhudu, a Central Water Commission official.
The loss is reported to be very high during the flood season, especially when the river is in spate. The overall yearly losses are in the order of 146 tmc. A shortfall of 4.55 per cent in the river flow has been observed between Koida, an upstream point and Polavaram.
The study is based on the discharge observations made by the CWC at its flow guage and discharge sites at Koida and Polavaram (from 1977 to 2006). Though the discharge observation at Koida was discontinued in 2006, the gauge observations still continue.
As many as 10,592 stage discharge records are available with the CWC. They were all taken during June 1977 to May 2006 at both the CWC points. There is a less discharge recorded almost for a major part of the year at compared to the upstream point. The big question queering the minds is what caused the huge water loss. The water availability at Koida is matching with the inflows from the upstream points. But the run off at Polavaram is less than even the run off at Koida.
The loss of water is always found in the river course even in lean flow days. It is very much reflected in daily, weekly, monthly, monsoon and non-monsoon average flows. In case of a further increase in the water loss, the water availability for both Polavaram and Sir Arthur Cotton Barrage at Dhawalewaram will be in question in future.
Some studies were conducted even by the Khammam division of the CWC. The water loss which remained a mystery was being attributed by some of the studies to the “big deep bed profile” existing in the river bed between Koida and Polavaram.
The yearly average run-off measured at Polavaram is (86,981 MCM) 3,072 TMC and it is (5,143 MCM) 182 tmc less than the run-off availability computed from Koida run-off. Similar losses are found some 200 km upstream of Polavaram at Gundlavagu project in Venkatapuram mandal of erstwhile Khammam district.
The studies that were conducted so far could not make out the exact location where the losses were occurring on such a large scale and why. It calls for a detailed geological investigation to identify the nature of the fault in the river bed profile. Once the Polavaram project is completed, there will be a massive impounding of water in the zone. The CWC official said the fault area should be treated properly to plug the faults before going in for impounding.
Need for prompt action
- In case of further increase in loss, water availability for both Polavaram and Sir Arthur Cotton
- Barrage at Dhawalewaram will be in question in future
- Flow loss assessed based on 29 years of data
- Similar fault zone observed near Gundlavagu project
- Treatment of river bed fault needed to arrest water loss