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-Aug04 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 (May04) 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 April04 16. 16 Beach formation in between the Groins G3-G4 and G5-G6(Oct04) 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 Oct02) 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 1241 N, Longitude 7454 E at North and ends at Latitude 817 N, Longutude 7705 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 Darcys 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