Pondicherry Tamil Nadu Beach Erosion

transcript

Pondicherry Beach Disaster Pondicherry Beach Disaster

ManMan--Made TsunamiMade Tsunami

ManMan--Induced Coastal Erosion at Pondicherry Induced Coastal Erosion at Pondicherry and neighboring beaches of Tamil Naduand neighboring beaches of Tamil Nadu

Pondy Citizens’

Action Network

(PondyCAN)

August 2008

www.pondycan.org

Once upon a time …Pondicherry had a beautiful beach (1986)

Pondy Citizens’ Action Network – August 2008

Nature’s gift to the citizens of Pondicherry (1986)

• Protects us from cyclones and tsunamis

• Prevents ground water from becoming saline

• Supports the livelihood of fishermen

• Provides a natural recreational space

• A unique and indispensible habitat for wildlife (sea turtles)

• Part of our heritage - used during festivals (Masimagam, Vinayaga Chaturthi)

THE BEACH… an essential part of the ecosystem

Then a harbour was built (1986-1989)……and neglected

Harbour entrance Pondy town 2 kms

Pondy was never the same …a precious gift was lost (2000)

How did we lose our beach?

Understanding The Coastal Environment

of the Pondicherry –

Tamil Nadu

(Coromandel) Coastline

The Pondicherry and Tamil Nadu coastlines are composed of sandy beaches, dunes and estuaries:

Rivers bring sand to the sea and feed the beaches.

Sand deposited along coast forms Estuaries, dunes, beaches.

The Cauvery Delta brings large amounts of sediment.

DunesBeachesEstuaries

Images: source Google Earth

Pondicherry

Pondicherry(Karaikal)

Tamil Nadu

Typical Profile of a sandy beach

South Pondy beaches – 1986-87 (Harbour construction

just started)

Vegetated dunes

Wide sandy beaches

Estuaries

PONDICHERRY TOWN’S COASTLINE – BEFORE - 1989

Sand bar

Dune – Beach Road is over an old dunePondy Citizens’ Action Network – August 2008

Coastal Processes along

Pondicherry –

Tamil Nadu Coastline

The most dominant process is: The Long Shore Drift (LSD):

the Natural Transportation of Sand

Mechanisms of sand transportation

Cross-shore movement

Mechanisms of sand transportation

Long-shore movement

Mechanisms of sand transportation along Pondicherry Coastline

During NE monsoon

During SW monsoon

Swell orientation

Direction of sand

movement

Image: source Google EarthPondy Citizens’ Action Network – August 2008

swellswell

During SW Monsoon (9 months):

6,00,000 cu.m

sand move North

During NE monsoon (3 months):

1,00,000 cu.m

sand move South

Net long-shore drift =

6,00,000 cu.m

(North -

1,00,000 cu.m

(South -

= 5,00,000 cu.m

move North

each year

500,000 Cu.m per

Sand movement is a significant natural process and a factor which plays a major role.

Net Littoral Drift

Interfering with the Littoral Drift

Source: unknown

Pondy Town

Tamil Nadu

Satellite image of Pondicherry coastline (Year 2000)

Pondy Harbour

Ariyankuppam Estuary

Eroding coastline

Accreting coastline

Profile of the Pondicherry coastline (year 2000)

PondyHarbour

Source: unknownPondy Citizens’ Action Network – August 2008

Pondicherry Harbour (built in 1986-1989)

Pondy Harbour mouth

Pondy town 1.5 kms

Breakwaters obstruct littoral drift

Sand depletion

Sand accumulation

Original shoreline

BreakwatersLittoral drift

Existing sand by-pass system at Pondy harbour

Original

shoreline

Submarine tunnel

Dredger

Sand nourishment

Proposed by: Central Water & Power Reasearch Station (CWPRS), Pune, 1978.

Designed by: Consulting Engineering Services (CES), New Delhi, 1981.

Dredging

Sand Nourishment

Sand by-pass system at Pondy Harbour

FAILED BECAUSE IMPROPERLY AND

SELDOM USED.

Consequences of disrupting

the Littoral Drift along Pondicherry –

Tamil Nadu

Coastline

Before (1986)

After (2002)

Pondy New Pier beach

Before (1986)

After (2000)

Pondy town beach

Before (2001)

After (2002)

Kottakuppam (TN) beach

Affected villages in Pondicherry & Tamil Nadu (2002)

1st August ‘02 … a week later

A house and trees… …turned into rubble and lost.

Parking space for traditional fishing crafts….is lost.

Widespread destruction

Homes…. livelihoods … and nature

Since the construction of the Harbour in 1989:- 8 kms of shoreline completely eroded- More than 30 km affected

Satellite image of Pondicherry and Tamil Nadu coastline (2006)

PondyTamil Nadu

PondyHarbour

Blocked sand

Seawall

Further disruption of the Littoral Driftcaused by

“hard” coastal protection measures:

1989 – 2007: Instead of nourishing the beaches, rocks were dumped along the coast.

Tamil Nadu

Seawall ends in Pondy… the problem shifts to Tamil Nadu

Sea WallPondy

Tamil Nadu

3 short groynes

TAMIL NADU

Seawalls & later groynes built in Tamil Nadu. 2002 – 2006.

Seawall

SoudanikuppamNadukuppamThandirayan

kuppam

Groyne construction work at Tandhirayankuppam, TN 4th May 2007

Groyne built North of Thandiyankuppam Village in Tamil Nadu May 2007

Erosion

Erosion at Quiet Beach, Thandhirayankuppam, TNas a result of groyne construction

April 2007 9th May 2007

Erosion at Quiet Beach, Thandhirayankuppam, TN

April 2007 6th June 2007

April 2007 28th June 2007

April 2007 18th July 2007

April 2007

9th May 2007

6th June 200728th June 2007

Erosion in 3 month’s time

18th July 2007

Dumping rocks and similar hard measures are not a solution

• Increases and transfers erosion down the coast

• Work has to continue forever as rocks keep sinking

• Requires huge sums of public money

• Does not protect us from big waves

• Mountains have to be destroyed

• Natural habitats for wildlife are destroyed

• The coastline is transformed and degraded

Is this sustainable?Pondy Citizens’ Action Network – August 2008

March 2002

Coastal erosion is advancing northwards at more than 350 m/year (1 m/day)

Kottakupam

…3 months later!

Challenges & Threats:

Proposed developments along SE coastline

that disrupt the Littoral Drift such as:

- Commercial Ports- Fishing harbours- “Hard” coastal structures- Artificial channels in seabed

Proposed Deep Water Port at Pondicherry

Existing harbour Proposed Deep Water Port.

Existing Harbour Proposed Harbour

• Land area: 150 acres.• Cargo handling capacity: 1.5 MTA.• Actual capacity: 0.05 MTA (average).• Breakwaters: 250 m long.• Depth: Max. 4 m.

• Land area: 400 acres (min.)• Cargo handling capacity: 20 MTA.• Breakwaters: 750 m long.• Depth: Max. 14 m.

Coastal erosion caused by disruption of littoral driftPotential situation in Pondy:

Potential erosion

Situation in Chennai:

Original shoreline

Existing erosion

Chennai Harbour

Proposed Pondy

Harbour(similar to Chennai harbour)Pondy Citizens’ Action Network – August 2008

Proposed Port developments likely to disrupt of littoral drift

Cheyur Port

Cuddalore Port

Karaikal Port

Nagapattinam Port

Pondicherry Port

IMPACTS OF COASTAL EROSION

• Destruction and loss of property

• Destruction and loss of natural habitats and wildlife

• Increased water salinity and scarcity

• Loss of livelihoods for fishermen

• Degradation of fertile agricultural land

• Exposes the coastline to cyclones

Do we need coastal developments that will:

• Increase coastal vulnerability

• Create water scarcity

• Damage the environment

• Endanger wildlife

..And ruin the quality of life of present and future generations

Concluding remarks:

• The disruption of the littoral drift is likely to be oneof the greatest challenges for coastal protectionand restoration.

• Unless we demonstrate that the littoral drift can be restored once disrupted, future coastal developmentswill result in greater damage to the coast.

• The restoration of the affected Pondicherry and TamilNadu coastline could present an opportunity for establishing coastal restoration practices for otherparts of this coast.

THANK YOU!

Pondicherry Tamil Nadu Beach Erosion

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