Discussing the various methods of coastal protection against erosion and the challenges faced during management of Indian coasts. Delineating the hard and the soft methods of coastal protection giving several case studies from all around the world and detailing few Indian ones from West Bengal, Tamil Nadu, Puducherry, Kerala and Gujarat.

1. 1
Coastal Protection Measures Along Few
Stretches of Indian Coast
nternational Workshop on Coastal River Zone Management, Regulations & Development
10th - 11th Jan 2013, IIT Bombay
Prof. V. SundarProf. V. Sundar
Department of Ocean Engineering,
I.I.T.Madras
&
Former Chairman, Asia Pacific Division of IAHR
Planned & Unplanned

2. 2
COASTAL ENGG. PROBLEMS ALONG THE
INDIAN COAST
Most major rivers drain into Bay of Bengal (Imbalance in
Sediments from rivers)Sediments from rivers)
Problems along east coast dominant
 Silting up of entrance channels
 Closing of river mouths
 Problems concerning aquaculture Problems concerning aquaculture
 Silting up of intake structures
 Erosion along the coast
Organisation of presentation
• Introduction
• Options under Soft & Hard measures
• Case Studies and proposed coastal protection
measures along selected stretches of maritimemeasures along selected stretches of maritime
states
West Bengal
Andhra Pradesh
Tamilnadu
Puducherry (Pondichery)
Kerala
Gujarat
• Summary

3. 3
Organisation of presentation
• Introduction
• Options under Soft & Hard measures
• Case Studies and proposed coastal protection
measures along selected stretches of maritimemeasures along selected stretches of maritime
states
West Bengal
Orissa
Andhra Pradesh
Tamilnadu
Puducherry (Pondichery)
Kerala
Gujarat
• Summary
A Few Typical damages due to coastal erosion

4. 4
Coastal Protection measures
HARD MEASURES SOFT MEASURES
Normal to the coastline [groins] Replenishment of coast withNormal to the coastline [groins]
Deposition Erosion Groins
Sea
Sea
Wave direction
Replenishment of coast with
sand.
At the landward side of the
dune [A]
At the seaward side of the
dune, landward of the dune
base [B]
At the seaward side of the
dune, seaward of the dune
base [C]
Parallel to the coastline on shore
[seawalls]
C B A
Seawall
Land
Sea
Parallel to the coastal offshore
break waters
Land
Land
Offshore breakwater Wave direction
Groynes, Jetties & training walls
Oldest groins (1503),Vissingen, Netherlands
T-Groin field protecting the coast of Florida
Suitable in areas where LST is predominant
Normandy Island
Groin field
Jetties

5. 5
Offshore Detached Breakwaters
Danish coast
Elmer offshore breakwater
Design features

6. 6
Artificial Beach recharge schemes
Sand replenishment from the
nearshore on to the beach
Before
Department of Ocean Engineering, IIT Madras, Chennai , India – 600 036
Beach replenishment in miami
After
LONGSHORE CURRENT -ANIMATION
Q=0 Q further increases
Oblique wave
Q increases
Wave direction Normal

7. 7
LONGSHORE CURRENT -ANIMATION
OBJECTIVES OF THE PRESENT WORK
Coastal challenges along the Chennai coast
The problems around the Chennai coast attempted by IITM is addressed in
this lecture
The main seed for these problems is dated back to one and a quarter
century, that is the construction of Chennai Port(Man made problem).
3
1
4 5
1. Coastal erosion on the northern coast Chennai port
2. Choking up of Cooum River mouth
3. Coastal erosion towards the north of River Cooum
4. Coastal erosion beyond the north Chennai groin field
5. Proposal of Chennai Port Mega Terminal
23

8. 8
Location map of the site
WEST BENGAL
Usage of Ballas on the western
side of the coast near the road
near Chandpur
STATUS OF THE COAST in mid 2007
Usage of Ballas on the eastern
side of the coast near the road
near Chandpur
Dhiga beach- view towards east of
SeaHawk hotel
High tide
penetration into
the sand dunes

9. 9
STATUS OF THE COASTAL PROTECTION FROM MID 2007 to
EARLY 2008
Status prior to protection
Completed portion of the protection
Some problems with Geo-tubes

10. 10
Coastal protection measures for Uppada, Andhra Pradesh
BREAKWATER
N LITTORAL DRIFT
COASTAL ENGINEERING PROBLEM
NEAR MADRAS
Northern breakwater
Southern
TAMILNADU
I N D I A
MADRAS
MARINA BEACH
+VE
LAND
Wave direction
-VE
-VE (Sand bar)
HARBOUR
BASIN
+VE
RIVER COOUM
MAN MADE PROBLEM

11. 11
STATUS OF THE STUDY AREA PRIOR TO THE PROTECTION
Swallowing of Temple
Temple about to be
Sacrificed to the sea
TEMPLE BEING SACRIFICED
g p
by Erosion in process

12. 12
Satellite
Port
K hi kkCreek
Ennore Expressway
Thiruvoutiyur High road
Shoreline
Sand trap
A new 500m long groin
A new 250m short groin
N
Phase 1
G i fi ld i th 2 t t h t b
Stretch I (2.0km)
Proposed 6 groins
by IIT Madras
(Not to scale)
Ernavoor
bridge
Ernavoor
ICI Ltd.
Ennore
E.I.D Parry
Kathivakkam
Ennore
C A new 250m short groin
Groin fields in the 2 stretches to be
completed by May.
Monitoring of the shoreline & if possible
sand by-passing from ennore port
Numerical, physical model studies &
field studies
Harbor
Royapuram
Tondiarpet
Tollgate
Eveready&co
Stretch II (1.5km)
Proposed 4 groins
by IIT Madras
(Not to scale)
0 0.5 1.0 1.5 2.0 km
Phase 2
Long and short Groins near ennore
creek mouth.
Groin 6
Beach formed
Beach formed on the south of Groin 6
North of Groin 6
Beach formed on the south of Groin 6
Beach Formation South of Groin 6 (Royapuram) in July-Aug’04
N
Groin 6

13. 13
Groin 6
length: 165m
As on 13/08/04 (3684 sq.m)
As on 25/08/04 (6973 sq.m)
As on 14/09/04 (8800 sq.m)
As on 06/01/05 (4660 sq.m)
As on 21/01/05 (10452 sq.m)
Work commenced in May 2004
BAY OF BENGAL
30 m
To ENNORE
15 m
30 m
SEA WALL
60 m 90 m
SEA WALL
120 m 150 m 180 m 210 m
GROYNENO:6
60 m
NORTH
45 m
70 m 300 m
240 m
To PARYYS
270 m
GROYNENO:5
SOUTH
Groin 5
length: 200m
Area =10452 Sq.m
N
Groin 6
Groin 5
SEA WALL
Satellite Imageries of Stretch 1
G5
G4
G6
G6
G5
(ROYAPURAM)
G2
G3
G1 G4
G2
G3
G1
G6Less erosion protected with seawall

14. 14
WAVE DATA
 The coastal region around India is divided into 10 grids,
each of size 50 latitude and 50 longitude.
 The present study area comes under the grid located at
10 – 150N and 75 – 800E in the wave atlas representing grid
number six.
 The wave data obtained
from wave atlas is for
deep-water conditions.
B A Y
VISAKHAPATNAM
3
2
15°
20°
25° N
65° E
25° N
20°
15°
70° 75°
80°
85°
90°
ARA
10
9
1
B A Y
O F
B E N G A L
I N D I A N O C E A N
6
7
8
4
TUTICORIN
MANGALORE
MADRAS
5°
65° E
70° 75° 80°
85°
90°
95°
5°
10°
10°
K
E
R
A
L
A
TAMIL
NADU
5
BIANSEA
Before Restoration

15. 15
FINAL LAYOUT
G1
G3
G2G4
G5
G6
G7
G8
G9
G10
G11
G12
Layout of groin field for Simon Colony, Vaniyakudi and Kurumbanai villages
Groin abutting the
rock outcrop
Shoreline evolution on Eastern side due to
the construction of Groin G9-G10 (May’04)
Groin G9-G10
Groin G9-G10
Shore line evaluation in between
Groins G9-G10 and G11-G12
Rock outcrop near Groin G9-G10
Beach formation on the
Eastern side of Groin G9-G10
Status of beach in April’04

16. 16
Beach formation in between the Groins G3-G4 and G5-G6(Oct’04)
A view of the shoreline from the eastern of the groins G5-G6 (oct04
G3
G4
G5
G6
Rock outcrop
During the tsunami of 2004, the beaches formed
due to the present groin field had acted as buffers
due to which the inundation distance and run-up
heights had reduced leading to almost nil damage.
The tsunami had exhibited its might on the
villages adjoining the study area. The groin field acts
as coastal protection measure, but also has
enhanced the livelihood of the fisherman as the
S b t th i fi h l diSpace between the groins serve as fish landing
centre.
This success has lead to a great demand for
groins along the coastal areas.

17. 17
Prior 2006
IIT M proposal (2007)
Ratchagan Street (Kanyakumari)
Present (2008)
Kilmanakudi
MEL & KIL MANAKUDI
Melmanakudi

18. 18
MANAKUDI AFTER TRAINING WALLS
PONDICHERY

19. 19
Southern
Breakwater
Pile supported
Jetty
Northern
Breakwater
A view of breakwaters at Pondicherry
The erosion and
accretion is estimated
from 1986 to 2002, i.e.,
over a period of 16 years
with the satellite imagery
data using GIS software.
The rate of
erosion is about 4m per
year and the accretion is
6m per year.
The extent of
erosion in the northern
side is 33.59 hectares
compared to the
accretion on southern
side of 30.71 hectares..

20. 20
Offshore
Breakwater
Northern
B k t
Inlet
channel
Submarine
Tunnel
Pile supported
Jetty
Southern Groin
Breakwater
SAND BY-PASSING IN
Total quantity of sand bypassing
= 0.4 million cu.m (mar to
Oct’02)
PONDICHERRY
BEFORE SAND BYPASSING
January 2002
A VIEW OF SHORELINE NEAR GANDHI STATUE
AFTER SAND BYPASSING
October 2002
BEACH WON

21. 21
A VIEW ON NORTH SIDE
OF GANDHI STATUE
(BEFORE SAND BYPASSING)
January 2002
FORMATION OF
BEACH ON
NORTH SIDE OF
GANDHI STATUE
(AFTER SAND
BYPASSING)
October 2002
C t f K l St t t t f
INTRODUCTION KERALA
• Coast of Kerala State starts from
Latitude 12°41’ N, Longitude
74°54’ E at North and ends at
Latitude 8°17’ N, Longutude
77°05’ E at South.
• Kerala has 560 Kms of coastline
of which about 350 Kms is
already protected by sea walls.
• There are 44 rivers in Kerala.
• Besides the Port of Kochi (a Major
Port governed by Major Port
Trusts Act, 1963), there are 3
Intermediate and 14 Minor Ports
in Kerala.

22. 22
Strengthening of existing seawall
(as a protection till the construction of
groin field)
Typical cross section of
contd…
THIRUVANATHAPURAM DISTRICT
Panathurakara
Thiruvanathapuram kollam Alappuzha Ernakulam Thrissur Malappuram Kozhikode Kannur Kasargod
Typical cross section of
conventional sea wall
Typical cross section of
sea wall using PP Gabions
Typical cross section of
sea wall with Toe Gabions
Janarthanapuram
Varkala beach is an important tourism and heritage spot.
THIRUVANATHAPURAM DISTRICT
Thiruvanathapuram kollam Alappuzha Ernakulam Thrissur Malappuram Kozhikode Kannur Kasargod
PROBLEM
•Plenty of scope to convert the location as a major attraction.
•Site with predominant cliff erosion.
North of Janarthanapuram (Varkala Beach) South of Janarthanapuram (Varkala Beach)

23. 23
SOLUTION
THIRUVANATHAPURAM DISTRICT
Janarthanapuram
Thiruvanathapuram kollam Alappuzha Ernakulam Thrissur Malappuram Kozhikode Kannur Kasargod
10 m 3 m
+5.50 m
Cliff
Gabions
2m x 2m
MSL
Protection of the cliff with seawall and gabions.
Submerged geotubes for reduction of wave energy.
GEOTUBES OF WIDTH 4.44 M AND OF HEIGHT 1.54 M FILLED WITH SAND
5.0m
MSL
GEOWOVEN TEXTILES
FLEXIBLE GEO BAGS GWF 40-220 OF SIZES 0.5M X0.5 M
EACH 0.2M THICK OF OVERALL SIZE 3M X 1 M
GEO CONTAINERS GWF 38-285 2m X 1.50m X 1m
OF 1M HEIGHT ABOVE BED
SOLUTION
It is proposed that the existing seawall be rehabilitated with the cross-
ti d b IITM h b l th t l l f hi h h ld b
ERNAKULAM DISTRICT : Nayarambulam-North
Thiruvanathapuram kollam Alappuzha Ernakulam Thrissur Malappuram Kozhikode Kannur Kasargod
section proposed by IITM as shown below, the top level of which should be
at +4.00 m
Transition groin
field as a long-term
measure

24. 24
Is it role of vegetation?
Tsunami Heights =3-4m
BG
Design Questions
Dt
Greenbelt Parameters
D
SP

25. 25
DEFINITION SKETCH OF VEGETATION AND POROSITY
Dt
Regular Arrangement Zig-Zag Arrangement
BG
SP
BG
Porosity =[(SP-Dt)/SP]
SP=c/c distance between Vegetationg
Dt=Diameter of Vegetation
BG=Breadth of Green belt
EXPERIMENTAL INVESTIGATIONS
BG=0.25m:D=1.65mm:SP=37.5mm(RE) BG=0.25m:D=1.65mm:SP=37.5mm(RE) BG=0.25m:D=5.5mm:SP=37.5mm(RE)

26. 26
3.5
4
SP/Dt=3.75
SP/Dt=3.75
SP/Dt=7.5
SP/Dt=12.5
Resistance in terms of Darcy’s f in Steady Uniform Flow
Reduced
Velocity, Vr
(V/fD)~4.0
1
1.5
2
2.5
3 SP/Dt=25
SP/Dt>3.75
Darcy's'f'
0
0.5
0.3 0.4 0.5 0.6 0.7 0.8 0.9
Froude Number
SP/D ~3.75: Proximity Effect Predominant
Vr~4.0: Wake Effect Predominant
SUMMARY
• An overview on the options for protecting
th t i t i hi hli ht dthe coast against erosion was highlighted
• A few case studies was discussed in brief

27. 27
Under normal conditions
INUNDATION OF INTERINUNDATION OF INTER--DUNAL FLATSDUNAL FLATS-- MOVIESMOVIES
Tsunami traveled up to 1km, with
a height of even upto @10m
Thanks for your
kind attention