Many people spend sleepless nights from June every year when the Southwest Monsoon sets in along the Western Coast, including that of Karnataka. They fervently hope that the raging waves of the Arabian Sea do not wash them away when they are in deep sleep.
This has been the tale of every resident, poor or rich, living along the Karnataka coast, particularly sea erosion-prone areas, including Batpady, Ullal, Meenakaliya in Dakshina Kannada and Hejmady, Kaup, Malpe-Padukare, Maravanthe, Koderi, Uppunda, Byndoor and Shiroor in Udupi districts.
Intensified erosion
With the revival of Monsoon from July first week this year, residents of Batpady on Karnataka-Kerala border were asked to move out of their beachside houses to Kalaji Kendras. Elderly B. Fathima was seen reluctantly moving out of her house saying she had an emotional attachment to the house built by her late husband. While she was living there for about two decades, the erosion has intensified over the last four-five years, she said.
However, the disappearance of the Monsoon from July-end has, ironically, brought relief to thousands of people like Ms. Fathima who though it spelt doom for other sections of people, mainly farmers.
Pandanus shrubs that grow along beaches wherever freshwater flow from streams to the Sea is available, effectively prevent not only Sea erosion but also the impact of the cyclonic wind. A bunch of Pandanus shrubs near Koderi in Udupi district. | Photo Credit: ANIL KUMAR SASTRY
The triggers
About 10 km of beachfront from Ullal to Batpady to the South of Mangaluru has been witnessing the fury of the raging waves for more than a decade. Construction of the southern breakwater at the Netravathi-Phalguni (Gurupura) river mouth for smooth navigation of fishing vessels to and from the Mangaluru fishing port is said to have triggered the erosion initially in Ullal. The government began dumping boulders along the affected coast to prevent erosion only to see the boulders getting washed away the next Monsoon.
Some offshore berms and inshore reefs constructed under Asian Development Bank-funded Sustainable Coastal Protection and Management Intervention Plan from 2014 at a cost of around ₹900 crore did not last long. Meanwhile, the erosion shifted further South swallowing the beachfront in Someshwara, Uchchila, and finally at Batpady. Another scheme was implemented, again with ADB funds, for Someshwara-Batpady, which was partially effective where groynes were built. Since groynes were not built at Batpady, they got completely destroyed, say local residents.
A similar situation prevailed on beaches to the North of Mangaluru, where severe erosions were reported at places that saw human intervention, in the form of building breakwaters for fishing harbours or construction activities. Sasihithlu Beach near Mulki is one such example where the verdant beachfront was completely destroyed after the construction of a bridge and a fishing jetty on Nandini river. It is said the coffer-bund erected for bridge construction altered the river flow into the Sea, thereby causing erosion.
Sea erosion protection walls built by dumping boulders were of little use to prevent erosion between Navunda and Koderi in the Udupi district. | Photo Credit: ANIL KUMAR SASTRY
At Maravanthe
Another important site that saw massive erosion was the Maravanthe beachfront in Udupi district where the Arabian Sea threatened to swallow National Highway 66. However, the construction of 24 groynes, 14 straight and 10 ‘T’ shaped ones, for a distance of 2.5 km from Maravanthe fishing outer harbour to Trasi, has almost prevented the erosion. However, massive erosion is being witnessed in Maravanthe fishing village after the construction of breakwaters for the outer harbour.
About 5 km long beachfront between Kirimanjeshwara and Koderi in Udupi district also became a victim of sea erosion after the construction of breakwaters for traditional fishermen who use the Koderi fishing harbour at the Yedamavinahole River mouth near Koderi. Vast extents of the shore got washed away along with a few houses even as the government dumped boulders at these sites that was of no use.
As many as 24 groyens, 14 straight and 10 ‘T’ shape, built along 2.5 km Trasi-Maravanthe beachfront under the Asian Development Bank-funded Maravanthe Shoreline Protection and Management Project since 2018, have not only saved the beachfront from erosion but also created sand deposits in Maravanthe, Udupi district. | Photo Credit: ANIL KUMAR SASTRY
Boulders not useful
Retired professor in marine geology with Mangalore University, Hejmady Gangadhara Bhat, said dumping of boulders as protection walls is not useful as the boulders cannot withstand the sea currents. The profile of each affected beach should be studied to find out the reasons for the erosion and suitable measures should be taken for protection. Groynes at Maravanthe Beach have substantially reduced erosion and helped sand deposits.
Mr. Bhat said sea erosion has been a natural process that has intensified with human intervention. About a Century ago, there was no road bridge on Netravathi river connecting Mangaluru with Ullal region and Kerala while people travelled by ferries. While the bridge was constructed, Adam Kudru, the highway was laid on the backwaters thereby interfering with the natural movement of the Sea and the backwaters. Then came the breakwaters for the fishing harbour. With these, the southern part of the beach at Ullal saw massive erosion while large sand deposits occurred on the northern part at Bengre.
Natural solutions
While sea protection walls built of boulders are of little use to prevent sea erosion, natural solutions by native species of creepers, shrubs and trees are far more effective not only to protect sea erosion, but also to protect landward properties from the onslaught of wind, including cyclones, said Y.K. Dinesh Kumar, Regional Director (Environment) of Coastal Regulation Zone, Dakshina Kannada and Udupi.
Mr. Kumar who has extensively travelled along the 320 km coastline of Karnataka in his pursuit to find natural solutions for erosion and wind impact, told The Hindu that creepers like Ipomoea pes-caprae (beach morning glory) on the first zone (from the Sea towards land) of the beach, bushy plants like Scaevola, Premna, Clerodendrum and Pandanus on the second zone, medium height trees like Noni and Bugari on the third zone and tall trees like Casuarina on the fourth zone can fortify not only the beach but also the inward land.
Except Ipomoea, other three varieties will also prevent the impact of cyclonic winds and spray of saline water on the landward vegetation as well as properties, he said. All these creepers, shrubs and trees will gel with the local environment since they are native varieties.
Sea erosion protection walls built by dumping boulders were of little use to prevent erosion between Navunda and Koderi in Udupi district. | Photo Credit: ANIL KUMAR SASTRY
Withstanding cyclone
Giving an example, Mr. Kumar said a 30 mtr long beachfront near NITK-Surathkal that has Scaevola shrubs withstood the Taukte cyclone onslaught and protected landward infrastructure while the adjacent stretch that did not have any shrubs was completely devastated.
In his previous posting as the deputy conservator of forests, Mangaluru Division, Mr. Kumar had developed eco-restoration models of beaches at Tannirbhavi and near New Mangalore Port on about 20 hectares of beachfront that have become success. Similar exercise should be undertaken along the entire coast, he suggested.
Whatever engineering measures, including groyens, reefs, etc., should be executed inside the water and not on the beach like boulder walls. Waves’ speed should be broken before they hit the beach to minimise the erosion impact, Mr. Kumar said.
As many as 24 groyens, 14 straight and 10 ‘T’ shape, built along 2.5 km Trasi-Maravanthe beachfront under the Asian Development Bank-funded Maravanthe Shoreline Protection and Management Project since 2018, have not only saved the beachfront from erosion, but also created sand deposits in Maravanthe, Udupi district. | Photo Credit: ANIL KUMAR SASTRY
Fish aggregates
Fisheries Department’s Fish Aggregates proposal at the wave breaking zone can not only boost marine fish production but also prevent sea erosion, he added.
The department has proposed these Aggregates to boost fish breeding by creating artificial islands made of tetrapods. The construction will be done after bathymetry study at the wave breaking zone inside the sea. The zone is identified at the place where the depth of the sea suddenly decreases landwards, that reduces the impact of waves on the shore. The aggregates thus also reduce the current speed while facilitating fish breeding, he said.
