World’s largest underground tunnel in irrigation sector at Devadula project, flooded

Hyderabad: The world’s single largest underground tunnel in the irrigation sector and also Asia’s largest vertical surge pool in the Devadula Lift Irrigation Scheme, have been inundated due to rising water levels in Godavari River. Due to the flood, the works of the tunnel, pump house and surge pool in Segment-3 have been disrupted.

Incessant downpour in the surrounding areas and subsequent heavy flooding have stalled the works of the project, from the Ramappa tank in Mulugu district to Dharmasagar in Hanmakonda district.

In a release, the officials of Megha Engineering and Infrastructures Limited (MEIL) stated that the flood water entered the 49 km-long single largest underground tunnel in the irrigation sector and also Asia’s largest vertical surge pool in the project, due to the overflow of water from the streams and ponds surrounding this area.

While the construction works have been scheduled for completion in a month’s time, the flooding could delay the works. The works on the first gate of the surge pool have been completed, while the ongoing works on the second gate are disrupted due to the unusual floods. This resulted in the submergence of construction machinery and relative tools.

The tunnel has been built by the MEIL under the Devadula Lift Scheme as part of the Segment-3 executed between Jakaram in Mulugu district and Devannapet in Hanmakonda. Six shafts and 10 audit points have been established in this tunnel. Water flows through these and reaches the surge pool constructed at Devannapet. The 135-metres-deep well-type surge pool with a 25-m dia and a pump house at a depth of 141 metres have been constructed.

Devadula Lift Irrigation has a unique shape when compared to other lift projects. An approach tunnel entry porter with a diameter of 5.6m was constructed at a distance of 4 km from Ramappa pond. A 49-km-long tunnel has been built for easy flow of water which reaches the surge pool constructed at Devannapet. The water lifted from the surge pool is fed through three pumps to the delivery system in Dharmasagar pond through a 6-km-long pipeline.