NEED OF SHORE PROTECTION

WORKS TO SAFEGUARD THE

LAND SIDE FACILITIES TO BE

CONSTRUCTED ON THE

WESTERN SIDE

NEED FOR SHORE PROTECTION

AT LAND SIDE

About 600 m to 700 m stretch of coast on the western side

breakwater is unprotected .

Due to the predominant northerly (westerly) drift, the coast

on the western side of the breakwater tends to be eroded.

By protecting the coast, in addition, the occasional break

out of the estuary water into the sea through the

unprotected coast line can be minimized.

Hence, it is necessary to provide a series of groins, at least

three groins to protect the coast line of nearly 630 m. This

would act as a shore stability structures for the safe

creation of land side facilities.

Satellite Map showing the Erayumanthurai side before

construction of Fishing Harbour

Feasibility Study By IITM Fisheries department, Govt of Tamil Nadu engaged the

services of Ocean Engineering Department in IIT Madras vide

Director's Letter no RC No :T1/7038/2012 dated

5.9.2013 .

The professors from Ocean Engineering Department of IIT,

Madras Prof. S.A.Sannasiraj and Prof.V.Sundar visited these

coastal area three times on 27.9.2013, 4.10.2013, and

20.11.2013.

The Chief Engineer, Fishing Harbour Project Circle, Chennai

and The Director, Central Institute of Coastal Engineering

for Fishery (CICEF), Bangalore visited these sites on

26.11.2013.

CICEF insisted for the Construction of RMS wall for Shore

protection of the western side of Main Breakwater in

Irayumanthurai, based on the report from IIT Madras and

expressed the immediate need of this works to safeguard

the Fish Landing Facilities for the Erayumanthurai side

villages.

Waves over flowing Land on western side of Main Breakwater

where the Land side Facilities proposed

TIDAL VALUES

Mean high water Spring tides level = + 0.79m

w.r.t Chart Datum

Mean high water Neap tides = + 0.59m

Mean Sea level = +0.49m

Mean low water Neap tides = +0.43m

Mean low water Spring tides = +0.18m

Waves over flowing Land - view from Main Breakwater

towards west

PROPOSED SITE DETAIL

Due to High wind waves on 15th April 2014 , the sea water

flowed over the Land area on western side of the main

breakwater where the land side facilities proposed.

In view of predominant long shore drift accompanied by the

cross shore sediment movement which is quite visible from

the field observation, coastal protection measures have to

be suitably proposed.

As the land side facilities are proposed to be over a strip of

land in between the Sea and the river Thamaraparani,

utmost care should be taken in protecting it from coastal or

river hazards.

From the coastal side, it is proposed to construct a seawall

of length about 650m, on the western side of the existing

western breakwater of Thengapattanam harbor.

Western side of main breakwater where 650m RMS wall is

proposed

LOCATION DETAILS

The Location of the 650m long RMS wall with +5m height is

proposed as below,

At the western end – from existing RMS wall on

Erayumanthurai side -UTM 738145.76mE and 912010.41mN.

At the eastern side – LS 50m of Main Breakwater - UTM

738668.32m E and 911628.61m N.

Western side of main breakwater where 240m Diaphram wall

is proposed

Proposed coastal protection by seawall

-1.0

0.0

+1.0

+2.0

+3.0

+4.0

+5.0

+6.0

NGL+0.7

-0.3

+1.7

+5.5

+1.16LTLHTL

3

1

2.51

2.51

CORE MATERIAL (50 kg - 300 kg)

QUARRY STONES OF 1.5T - 2.5T WITH 75% OF

GREATER THAN 2T (1.85m THICK)

TOE MOUND (500 kg - 1000 kg)

1.5

1

GEOTEXTILE LAYER

All Dimensions are in "m"

Proposed cross section of the seawall