Coastal Erosion Control through Installation of Geo-textile Tube Embankment
A study on “Shoreline changes in Odisha” by Ministry of Environment & Forest and Climate Change, Government of India revealed that the coastline of Odisha is largely accreting (46.8%) and 14.4% is stable and 2.00% of the coast is artificial. Erosion (High, Medium and Low) accounts for 36.8% of the coast and out of 480 Km of the coast, only 8.2% are undergoing high erosion. One of the major reasons behind this erosion is regular storm surge and floods in the coastal districts of the State.
Pentha (20° - 32’ – 5’’N) (86° - 47’ – 5”E ) is an agricultural village in Kendrapada district along Dhamra – Paradeep stretch. The region connected with different rivers is Brahmani, Baitarani, Chinchiri, Pathsala, Maipura, Kharasrota, Barunei and Dhamara. The general topography is irregular with many drain cuts, rivers, lakes, ponds, swamps, estuaries, and lagoons. The coast is also known for sporadic nesting by Olive Ridley Turtles. The beach was separated by an earthen embankment having a height of approximate 3 meters and a length of about 1.5 Km. Out of this, about 400m long was most vulnerable to seawater intrusion, due to the fact that the coast is prone to erosion. The coastal stretch adjacent to Pentha village had been continuously eroded for the last few years. The site is more hostile with strong waves hitting the bank throughout the year. Seabed slope is sharper. The shoreline of Pentha was shifting towards the countryside.
- In 1960, The shoreline was 4000m away from existing old embankment.
- In 2001, The shoreline was 500m away from existing old embankment.
- In 2005, The shoreline was 200m away from existing old embankment.
- In 2006, The shoreline was 50m away from existing old embankment.
- In 2008, The shoreline was 20m away from existing old embankment.
- In 2009, The shoreline was 5m away from existing old embankment.
- In the year 2009-10, The a retard embankment was constructed on the backside of the old embankment at a distance of 60 meters length.
- Sea waves damaged the existing old embankment during the 2009-10 and the traditional method of protection using wooden stump piling and Big Resin PVC sandbag dumping was done in the year,2011.
- In 2011-12, The shoreline over-ran the old embankment for a length of 400 meters & washed away the embankment for 350-meter length.
In order to protect the coastline at Pentha from vulnerable erosion, Integrated Coastal Zone management (ICZMP) – State Project Management Unit & Department of Water Resources, Government of Odisha has taken up an up-to-date method of soft engineering technology which includes construction of geo-textile embankment under the assistance from the World Bank. It is a pilot project in the state of Odisha in which a structural system is to be developed to face wave action creating a threat to the existing Rajnagar - Gopalpur saline embankment for long-term protection. The success of this pilot project would be considered as a model for similar cases in another vulnerable area, of the coast which will go a long way to prevent the coastal erosion and protect land, property, and life. Besides, it will protect the coast during the natural calamity.
The various services and components are undertaken during the installation period are given below:
- The services of Ocean Engineering Department, IIT (Madras) was commissioned as the project consultant for a survey of the site, preparation of the designs, and provide technical guidance in the installation of geo-textile tube embankment including quality control and monitoring of the work. The consultant selected the site, prepared the design through field investigation and modeling studies.
- The work for construction of the geo-tube embankment was awarded to M/s Garware Wall Ropes Ltd., Pune.
- Length of 505m of shoreline was protected by Geo-Textile-tubes integrating with existing earthen retard embankment. The embankment is having 235 nos. of geo-tube filled with sand slurry and covered with a protective layer of the granitic gabion.
Benefit/ Impact of the Intervention
- Sand accretion in front of geo-tube is noticed.
- Increased the visit of the number of tourist to the site.
- Coastal village of Pentha is protected and less vulnerable to coastal flooding due to cyclones.
- Life and property of villagers of Pentha and other adjacent villages saved from furry of sea tides and waves.
- Agriculture fields of the local communities are saved from saline ingress and thereby the income of communities is enhanced.
- Local villagers gained confidence on the safety and security of their life & property as they have started (i) construction of Pucca house (ii) renovation of their thatched house and (iii) resettlement of people in Pentha who had left the village in the past because of life risky & insecurity.
- During a severe cyclone Hud Hud (12th October 2014) the seaside slope of retard embankment as protected by gabions are not affected at all and the accretion of sand has occurred in front of Geo-tube.