Chennai: Researchers at the Indian Institute of Technology-Madras (IIT-M) studied the flooding in and around Chennai and has proposed construction of ‘Straight Training Walls’ at the mouth of Ennore Creek to significantly minimise the flood risk on its upstream.
The study focused on extreme storm surge scenarios and high tide levels along with flooding in the river.
It found that heavy siltation in the creek mouth and narrow opening in the mouth posed a flood threat to the areas adjoining the river, a release from IIT-M said.
The study showed straight training walls at the creek mouth and some regular de-silting of the river would improve the situation and minimize the flood risk significantly in North Chennai.
It also showed that an alternative proposal of curved training walls proposed earlier will worsen the situation, by blocking the free exchange of seawater with the creek, thereby, increasing the flood risk.
The study was commissioned by Kamarajar Port (formerly Ennore Port) in Chennai to propose solutions to reduce flooding around Kosathalaiyar river banks.
It was undertaken by Prof K. Murali, Prof S A Sannasiraj and Prof V Sundar, faculty in the Department of Ocean Engineering, IIT-Madras.
Prof Sannasiraj said “based on the expertise and experience of IIt-M’s Department of Ocean Engineering the researchers working with training of river mouths, the proposal has been made to construct a pair of training walls extending perpendicular from the shore up to a water depth of -5m on either side of the creek.”
Prof Sundar said a straight structure with sufficient crest height was essential to ensure the tidal prism ingress for flushing.
Further, in the event the shoreline south of southern training wall reaches its tip, either dredging or its further extension into a water depth of 6 to 7m was feasible with ease.
The straight training walls would act in complement with the present series of groynes which were designed by IIT-M for shore protection too, he said.
In the history of flooding in and around Chennai, the three creeks–Adyar, Cooum and Ennore–remain as major bottlenecks due to sand bar formation at their mouths, resulting in significant flooding over the settlement along its banks, impact on coastal villages, disruption in fishing activity, industrial network on the upstream, road encroachments and illegal waste disposal.