×
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT

Work to stem sea erosion gets under way in Ullal

Last Updated 20 April 2015, 21:27 IST

To make sea erosion in Ullal, a thing of the past, one of the component of work on modification and re-alignment of existing breakwater at estuary is in progress.

The work is taken up as a part of ADB funded Sustainable Coastal Protection and Management Investment Programme (SCPMIP) to address issues of sea erosion in progress in Ullal, on a pilot basis.

The work proposed to bring in changes to breakwater situated on the northern side at Bengre has commenced. The north breakwater will be extended across the channel by 200 metre. The south breakwater will be  shortened by 150 metre, as a part of the ongoing work.

Altered north breakwater will ensure that sand coming from the river is driven south towards Ullal beach and that natural by‐passing occurs more effectively, said Sustainable Coastal Protection and Management Investment Programme Joint Director Gopal Nayak.

The breakwater was constructed (1991-94) to prevent sediment entering the estuary. To extend the north breakwater, concrete tetrapods will be laid. The work on the concrete tetrapods are in progress on the shores of Bengre. The work commenced in December, 2014 and is likely to be completed by June, 2016.

“Normally boulders are dumped to check sea erosion during monsoon. To extend the breakwater, there was a need for a large quantity of boulders. However, owing to the non availability of bolders, it was decided to use concrete tetrapods,” said an official. There is a need to strengthen the breakwater to check the waves.

In this background, tetrapods have been constructed depending on the intensity of the waves. The places where waves are strong, 7 tonne weighing tetrapods will be laid, where it is of low intensity, then four tonnes of tetrapods will be laid. For the normal waves, two tonnes weighing tetrapods will be laid,” the official added.

“When waves lash boulders, the pressure on boulder increases,. However, when it lashes on tetrapods, the water flows between the tetrapods and the intensity of the waves reduces,” said Nayak.

The work is being monitored by the PWD, Ports and Inland Water Transports department and the work is entrusted to Mumbai based R B Chuhan-Arjun Earth Movers.

Detailed investigations by the consultant to prepare report on sea erosion  based on field and numerical model studies have revealed that Ullal beach is eroding for two key reasons—the alignment of the beach is not in equilibrium with the wave climate, with extremely large amounts of sand being lost to the south each year and insufficient sand is being provided from the northern beaches and the river, due to several factors including the northern bias in the alignment of the breakwater.

“The work on shortening the south breakwater will commence by the end of April. With the completion of the work on two break waters, the sand will starts moving towards the Ullal beach. In case, if the quantity of sand accumulated is less, then beach nourishment work will be taken up at a cost of Rs 18 crore. To nourish the beach and fill the geotextilecontainers will be sourced from the shoals that exist in the Ullal inlet and Netravati river bed. A layer of 1 m of sediment will be removed over the channels,” the official said.


ADVERTISEMENT
(Published 20 April 2015, 21:27 IST)

Follow us on

ADVERTISEMENT
ADVERTISEMENT