Government of Tamil Nadu Wapcos Limited
Total Page:16
File Type:pdf, Size:1020Kb
GOVERNMENT OF TAMIL NADU DEPARTMENT OF FISHERIES ENVIRONMENTAL IMPACT ASSESSMENT STUDY FOR PERMANENT STABILITY OF COASTAL INLET AT THAMRAPARNI RIVER AT PUNNAKAYAL, THOOTHUKUDI DISTRICT WAPCOS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING) Flat No.2C,IInd Floor, Jai Durga Apartment,38/2 First Avenue, Ashok Nagar, Chennai-600 083 Tel: 044-24710477 Fax: 044-24174424 Email: [email protected] APRIL 2014 Department of Fisheries EIA Studies for Permanent Stability Government of Tamil Nadu of Coastal Inlet at Thamraparni River EXECUTIVE SUMMARY 1. INTRODUCTION The coast along the state of Tamil Nadu is very dynamic in nature due to occurrence of various development activities along the coast, which leads to sea erosion along the coast. In Punnakayal, there is a fish landing facility with land based facilities available inside the mouth of River Thamiraparani. Due to the littoral drift, the river mouth is dynamic and hence hinders the free movement of fishing boats. To facilitate the smooth movement of fishing vessels, Department of Fisheries, Government of Tamil Nadu is proposing a permanent stability structure at the inlet of the River Thamiraparani at Punnakayal. 2. NEED OF THE PROJECT As a part of obtaining the CRZ clearance from TNCZMA/MoEF for the proposed permanent stability structure in the inlet of River Thamiraparani at Punnakayal, Department of Fisheries has appointed WAPCOS Limited, A Government of India undertaking, under Ministry of Water Resources to carry out the EIA study. The main objective of the proposed EIA study is to assess the positive as well as negative environmental impacts likely to accrue as a result of the proposed training wall. 3. ENVIRONMENTAL IMPACTS The marine ecological survey carried out in the project area reveals that the water is well oxygenated and nutrients are adequately supporting fairly good plankton population, the base in the food chain. Thus, the water is biologically productive at primary and secondary levels and the benthic fauna is moderately rich in diversity. 4. SHORELINE MONITORING PROGRAM A shoreline monitoring program has been suggested to assess the behavior of the shoreline due to the proposed construction of permanent stability structure at the inlet, since there is a paucity of information on the behavior of WAPCOS Centre for Environment 1 - 1 Department of Fisheries EIA Studies for Permanent Stability Government of Tamil Nadu of Coastal Inlet at Thamraparni River coastline to the construction of the structure in this area. The monitoring program shall encompass a combination of bathymetry surveys and shoreline surveys prior to construction of the project and during and after the construction are recommended. 5. CONCLUSION The EIA study conducted has revealed that due to the construction of the permanent stability structure at the inlet, there will be an overall positive impact on the ecosystem of the inlet and the mangroves. Besides, the proposed training wall will not only help to keep the inlet open but also will help in providing a tidal flushing of the area. This will lead to increase in the productivity of the associated mangrove areas. Also the local fishermen will get the benefit of using the fish landing centre throughout the year which will in turn have a positive impact on their livelihood. WAPCOS Centre for Environment 1 - 2 Department of Fisheries EIA Studies for Permanent Stability Government of Tamilnadu of Coastal Inlet at Thamiraparani River CHAPTER-1 INTRODUCTION 1.1 GENERAL The Tsunami disaster of December 26, 2004 had devastated many areas along the Indian Coastline. The state of Tamilnadu was badly hit leaving a trail of disaster. It is estimated that about 8000 persons lost their life in the disaster and damaging the properties of many more. The infrastructure was badly hit as a result of the Tsunami. The damage to fisheries infrastructure including closure of bar mouths in the wake of disaster has restricted access of the fishermen to sea, thus affecting fishing activity. Rehabilitation and reconstruction efforts offer opportunities for realizing the integrated coastal zone management and sustainable coastal livelihoods in the affected areas. 1.2 PROJECT DESCRIPTION The proposal for the improvement as recommended for Permanent Stability of Coastal Inlet at Thamiraparani River contemplates opening of southern mouth of Thamiraparani River by dredging a 75m wide lead channel with a depth of - 2.0 m CD. This channel will extend opposite and away from the edge of Punnakayal jetty up to -2.0 m depth CD contour in sea. In addition, a 1.5 Km long interconnecting channel between southern inlet and northern branch is proposed to be dredged to divert flow towards south inlet from dominant branch of Thamiraparani River situated on the north. The width of this interconnecting channel is proposed as 50 m and it will be dredged up to -1.5 m CD. In order to arrest the littoral drift from south, a 200 m long groin is proposed at a distance of 200 m south from the bank of inlet channel and it will be extended up to -3.0 m depth CD contour, a 200 m long Berthing Structure is proposed at western side of existing wharf. A 650 m long approach road is proposed with forming of bund with boulders, divided in two portion Channel portion (330 m) and Island portion (320 m) for transportation of quarry stones for Groin and for navigation of boats in channel portion, 21 m long Linking structure is proposed. For connecting existing wharf and proposed berthing structure, 49 m long stone pitching is proposed. 1-1 WAPCOS Centre for Environment Department of Fisheries EIA Studies for Permanent Stability Government of Tamilnadu of Coastal Inlet at Thamiraparani River Accordingly, Mathematical Model Studies were conducted by considering the above parameters and the conclusions & recommendations of model studies are as follows: i) The Tamirabarani River is a seasonal river which receives upland discharge only during NE monsoon. The river has very flat slope in coastal area hence it bifurcates into several branches to discharge the rainwater rendering all inlets very weak. Two inlets are prominent • South inlet near existing jetty • North inlet in front of main existing river Northern inlet is stronger than Southern inlet for Tamirabarani River. ii) Literature survey indicates the gross littoral drift is only 0.0875 million cum/annum. The 1-D mathematical model shows that tidal prism is 0.55 Mm 3, thus Ω/M is less than 10. This indicates that the inlet is very unstable. iii) The 2-Dimensional model study indicates that sediment movement activity in this region is very less. This is also corroborated by general information about dredging activity near V.O.C (Tuticorin) Port. iv) Even against meager littoral drift the river could not maintain inlet throughout the year. Hence it is proposed to protect the inlet by putting a groin on one side. Comparative advantage/disadvantage studies suggest maintaining southern inlet. v) The proposal of improvement contemplates: A 75 m wide lead channel dredged to -2.0 m depth below CD. The channel will extend from jetty end up to -2.0 m depth contour. This channel has been provided to facilitate navigation of boats. The connecting channel of 1.5 Km long between Northern branch and southern inlet to divert flow towards south inlet from dominant branch of the river situated on the North. The channel width will be 50 m and dredged up to -1.5 m below CD. 1-2 WAPCOS Centre for Environment Department of Fisheries EIA Studies for Permanent Stability Government of Tamilnadu of Coastal Inlet at Thamiraparani River A 200 m long groin extended up to -3.0 m depth contour at 200 m south of inlet channel edge. vi) The 2-D model studies indicate that with this arrangement the inlet will fall in erosion zone as such the same will be maintained. vii) As the channel inlet is dredged to -2.0 m depth there will be little siltation at the inlet which is likely to be flushed out in rainy season. viii) Because of presence of low littoral drift maintenance dredging is not anticipated at this stage. In absence of monsoon rain in some year removal of deposited materials at the inlet may be required if it restricts boat movement. ix) Furthermore, the founding level of Punnakayal Fishing Jetty is -1.0m below CD, hence it is not recommended to dredge in the area opposite to the existing jetty. A new jetty needs to be constructed to handle larger boats by the side of existing jetty. It is recommended that this new jetty must be constructed with the higher depth of penetration of piles. x) For connecting existing wharf and proposed berthing structure, 49 m long stone pitching is proposed. xi) A 650 m long approach road is proposed with forming of bund with boulders, divided in two portion Channel portion (330 m) and Island portion (320 m) for transportation of quarry stones for Groin and for navigation of boats in channel portion, 21 m long Linking structure is proposed. xii) The total cost of the project is estimated as Rs.1800 Lakhs. 1.3 STAKEHOLDERS’ MEETING The Stakeholders’ meeting was conducted on February 29, 2008 at Punnakayal site, in which the local fishermen representatives and the Department of Fisheries Officials participated. The suggestions given by the local fishermen representatives and the Department of Fisheries Officials during the Stakeholders’ meeting were considered in the final recommended proposal of improvement, which are as follows: 1-3 WAPCOS Centre for Environment Department of Fisheries EIA Studies for Permanent Stability Government of Tamilnadu of Coastal Inlet at Thamiraparani River To open and stabilize permanently the southern mouth of Thamirabarani River, which is close to Punnaikayal Fishing Jetty To construct the groin at a distance of 200 m to the south side To deepen the interconnecting channel by dredging the portion between the southern mouth and northern branch To construct a retaining structure on the southern bank of the dredged cut opening.