Coastal Processes and Shoreline Management Initiatives of - - PowerPoint PPT Presentation

Coastal Processes and Shoreline Management – Initiatives of ICMAM/MoES

Scientist-F & Head (Coastal Processes & Shoreline Management Group)

1. The coastal areas have been experiencing a number of changes: 2. Careful understanding and estimations of coastal processes i.e. Tide, Current, Wave Tsunami, Storm Surges, Sediment transport, Shoreline evolution, etc, is very important

Coastal Process studies and Shoreline management (Since 2003 onwards...)

 accelerated changes in shoreline: loss of beaches and closures of inlets,  degradation /changes of coastal habitats and land use- land cover  increased coastal erosion & flooding due to extreme events and sea level rise  changes in sediment transport pattern and islands, including coral islands  Pressures of developmental activities along the shoreline (ports, harbours etc)

Tsunami, Storm Surges, Sediment transport, Shoreline evolution, etc, is very important to deal with various long-term variations in the coastal zone. 3. ICMAM has invested its energy in deal with these processes in small way at local scale through scientific experiments using monitoring, measurements, modelling, Mapping and Management (5 M approach) 4. Management solutions provided by ICMAM are partially implemented at few locations 5. Currently ICMAM focus is to i) assess the sediment transport rates at selected locations and ii) Long term and annual shoreline changes along Indian coast

ANDHRA PRADESH ORISSA MADHYA PRADESH WEST BENGAL

BAY OF BENGAL

Gopalpur Gangavaram

Shoreline Management Programme during X and XIth plan- First project of this nature in India

Vengrala Ratnagiri

TAMIL NADU

ARABIAN SEA

BENGAL

INDIAN OCEAN

Karwar

Kozikode

Vadanapally Kundapur Muthalapozhi Honnanar Malpe

NIO, Goa CESS, Trivandrum Chennai

• ICMAM had lead role in implementing these projects in association with various institutes NCESS, NIO, IITM, NITK, BU, AU etc

Objectives

• Assessment of coastal erosions (Monitoring
• f Shoreline changes, beach profile, LEO etc)
• Understanding coastal processes through

desk, field data and mathematical modelling studies.

• Preparation of Shoreline Management plan.

 16 locations (2003-12) + 2 Loc (2012-17)

During X plan:

• Panathura(Kerala)
• Ennore (TN)
• Kayamkulam-Munambam
• Paradip
• Ullal (Karnataka)
• Vellar (TN)

Implementation of partial SMP for coastal Implementation of partial SMP for coastal protection at protection at Panathura Panathura

Predicted shoreline evolution Predicted shoreline evolution

• ver 25 years
• ver 25 years

Close grid nearshore bathymetry & Wave, current and sediment Numerical modeling for Shoreline Evolution based upon historic data Design of ‘T-groin field’, Implementation by Irrigation Dept. (Kerala Govt)

Performance now being monitored

Model studies predicted beach formation north of groin But beach formed south of groin Beach developed Beach developed after groin after groin construction construction

Monsoon erosion is mostly storm profile erosion – the data was not there and included in the model

Sequence of modelling

• Wave transformation
• Currents
• Sediment Transport
• Shoreline evolution

S [m] (meter) Above 0.4 0.3 - 0.4 0.2 - 0.3 0.1 - 0.2

4.5 5.0 5.5 6.0 6.5 (kilometer)

Morphological modelling to arrive conceptual coastal measures along Tidal Inlet at Mangalore

0.1 - 0.2 0 - 0.1

• 0.1 -
• 0.2 - -0.1
• 0.3 - -0.2
• 0.4 - -0.3

Below -0.4

11/02/2006 14:00:00 Scale 1:32580 8.0 8.5 9.0 9.5 10.0 10.5 11.0 (kilometer) 3.5 4.0

• 0.4 -

• 0.4 -

• 0.4 -

• 0.4 -

T-Groyne @3.5m depth Groyne @3.5m depth Submerged Reef@3.5m depth Groyne @4.5m depth

Spacing/Length=1.5 Spacing/Length<1.5

Various Coastal Engineering Solutions were tested for prevailing tidal, wave conditions to arrant the erosion in monsoon

Nearshore Wave interaction with structures

Recommended submerged reef

• Plans are conceptual solutions & subjective
• Lack of information / Generation of quality data
• Understanding the nature, causes Coastal Erosion for coastal protection– holistic approach

therefore

Shoreline Management (2003-2012): lessons learned

The project was reviewed by high level committee in 2012 and recommended to focus on Coastal Processes studies and Shoreline vulnerability assessment ( 2013 onwards…) Ongoing activities:  Shoreline change mapping - a coastal service on shoreline changes  Coastal Processes & Transport modelling- Understanding of the system & to provide technical support to coastal states and other user agencies  Coastal Change System- extent of coastal changes, classification & vulnerability assessment

Approach for Shoreline Monitoring for Indian Coast: Remote Sensing + Field Monitoring

Wide Beach

Distinct Morphology

Shoreline processes depend on morphology

Tidal Inlets Earth Cliffs Rocky Cliffs Pocket Beaches

Erosion & Shoreline changes are site specific and depend on human interventions.

Human interventions and shoreline changes

Et = ±

E2

s + E2 td + E2 c + E2 d + E2 p + E2 r + E2 ts

I. Seasonal Error (Es), II. Tidal Fluctuation Error (Etd), Positional Uncertainty I. Digitizing Error (Ed), II. Pixel Error (Ep), III. Rectification Error (Er), Measurement Uncertainty

y = 2.610 300 Distance from Baseline (Meters)

Monthly shoreline & Foreshore slope survey for positional uncertainty for a geomorphic systems

LRR

Plan view of uncertainty in data Plan view of uncertainty in data

EPR

Time no of yrs) between

• ldest

and youngest shoreline Distance in m between

• ldest

and youngest shoreline

(EPR) =

WLR

y = 2.610 R² = 0.923 50 100 150 200 250 1989 1994 1999 2004 2009 2014 Distance from Baseline (Meters) Shoreline Date (Years)

LRR

• 2nd Order polynomial is preferable (requires minimum of 6 GCPs).- used 10-12 GCPs – collected from field (90%)
• GCP’s spread evenly over the image, covering the whole image, and GCP were also placed in overlapping region to avoid edge

mismatch between the two or more images.

• RMSE maintained within pixel. 6-8 Check used for verifying rectification (Check point error ~ less than a pixel).

Protocols adopted for Geometric Correction to Shoreline studies:

• About ~35-38% of shoreline is experiencing erosion based upon 1990-2015
• Accretion is leading to closure of creek /inlet mouths
• Existing ~200 harbours & ports, Sea level rise also has impact on coast

SHORELINE TREND High Accretion Moderate Accretion Low Accretion Stable Low Erosion Moderate Erosion High Erosion

GJ Coastline Length : 1400 km Districts : 14 + 2 (UT) 1:25000 grid : 136

Shoreline Change (1990 Shoreline Change (1990-

• 2016)

2016)

Khambhat Suvali Beach Porbandar protected Beach Jamnagar Kuchadi Marsh land

Cumulative Shoreline Change (%) Cumulative Shoreline Change (%)

Jafarabad Rocky Cliffs Vanakabara Beach (Diu) Adri Rocky Coast

Class 1990-2012 1990-2013 1990-2014 1990-2015 1990-2016 High Erosion 3.2 3.4 2.9 2.7 2.3 Moderate Erosion 4.9 5.4 4.6 3.9 3.4 Low Erosion 34.4 35.5 34.4 34.5 33.0 Stable 29.7 26.5 26.8 28.2 29.3 Low Accretion 22.0 23.3 25.9 25.1 26.4 Moderate Accretion 3.3 3.4 3.3 3.5 3.7 High Accretion 2.5 2.5 2.2 2.0 2.0

SHORELINE STATUS BETWEEN 1990 & 2016

SHORELINE 1990

Legend

Pentha coast

Shoreline changes Odisha coast over 25 years: Examples of natural and human-induced erosion

10 20 30 40 50 60

EROSION STABLE ACCRETION

31 10 58

SHORELINE 2016

Gopalpur

Short term changes Short term changes- No trend, human intervention No trend, human intervention

• Poompuhar region is an eroding site for past few decades.
• 8 groins structures were constructed after 2013 along Poompuhur region.

11

12th June 2014 24th May 2013 22nd June 2012

Coastal Processes studies and Shoreline vulnerability assessment ( 2013 onwards…)

Ocean to Coast: Ocean to Coast: Wind Wave+ Current + Nearshore+ shoreline Model

Hydrodynamic and Sediment Transport Modelling

(South Maharashtra coast- Vangurala- Ratnagiri)

• Global model-regional-Local Model.:
• Wave Watch III & SWAN implemented to capture realistic local wave features for LST
• MIKE platform ( Wave, Tide, and current model) – for Suspended sediment transport

(Coarse, 1.0 x 1.0)-Indian Ocean (Mod, 0.1 x 0.1) -Arabian Sea (Fine, 0.03 x 0.03)-South Maha.

SWAN / MIKE21 MODEL WAVEWATCH III MODEL

(a) Large scale Wave Modelling

Model validation for of Hs, T &Dir

EMPIRICAL ESTIMATION

Offshore

LITPACK MODEL (Fine, 100x100m) (Fine, 10x10m)

Near shore (b) Regional Hydrodynamic modelling (100-500m grid): Integrating tide, wave, and wind influence to generate the composite energy regime in shallow waters (c ) Local scale wave model (5-10 m grid) to capture wave breaking, refraction, diffraction fine scale processes for sediment transport

One year N Ten years

Longshore Sediment Transport and Shoreline prediction modelling for Vengurla coast

Modelling for sediment transport estimations and Prediction of Shoreline Changes for 10 years

Location Net (m3/yr) Gross (m3/yr) Average

• 8511

1.18 * 105

One year Ten years

Longshore Sediment Transport and Shoreline prediction modelling for Vengurla coast

10 20 30 40 50 60 Erosion Stable Accretion

%

Gujarat, Daman & Diu

20 30 40 50 60

%

Maharashtra

20 30 40 50 60

%

Odisha

10 20 30 40 50 60 70 Erosion Stable Accretion

%

West Bengal

Arabian Sea Bay of Bengal

INDIA

1990-2015

Pentha (Sea wall) Kothapalayam Ratnagiri Jafarabad (Wavecut notch)

Fore shore Berm line

Back shore

Sediment characteristics

Coastal changes System for Indian coast

(on information needed for coastal development & management)

10 20 Erosion Stable Accretion

%

10 20 30 40 50 Erosion Stable Accretion

%

Goa

10 20 30 40 50 Erosion Stable Accretion

%

Karnataka

10 20 30 40 50 60 70 Erosion Stable Accretion

%

Kerala

10 20 30 40 50 Erosion Stable Accretion

%

Tamil Nadu

10 20 30 40 50 60 70 80 Erosion Stable Accretion

%

Puducherry

10 20 30 40 50 60 Erosion Stable Accretion

%

Andhra Pradesh

10 20 Erosion Stable Accretion

%

• Sl. No

State Km 1:25,000 scale grid 1 Tamil Nadu & Puducherry 1055 81 2 Andhra Pradesh 978 89 3 Odisha 474 47 4 West Bengal 422 30 5 Karnataka & Goa 340 34 6 Maharashtra 734 45 7 Gujarat, Daman & Diu 1404 136 8 Kerala 542 55 Total 517

Kizhunnapara beach (Tombolo morphology) Kothapalayam (Sand dunes) Solai Nagar (Sea wall) Kodimunai (Sea wall) Ratnagiri (Rocky terrace)

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