geomorphological evolution of teknaf peninsula

NISHAT FALGUNEE

SHAHREEN MUNTAHA NAWFEE

JUEL RANA KUTUB

GEOMORPHOLOGICAL EVOLUTION OF TEKNAF PENINSULA

4TH YEAR 2012

DEPARTMENT OF GEOGRAPHY AND

ENVIRONMENT

UNIVERSITY OF DHAKA

INTRODUCTION

TWO BROAD CATEGORIES OF

GEOMORPHIC PROCESSES

ARE:

ENDOGENIC PROCESS:

WORKS FROM WITHIN THE

EARTH.

EXOGENIC PROCESS: WORKS

ON THE SURFACE OF THE

EARTH.

GEOMORPHIC EVOLUTION MEANS THE ORIGIN AND DEVELOPMENT OF A PARTICULAR AREA BY THE GEOMORPHIC PROCESSES ACTIVE IN THAT REGION

EXOGENIC

PROCESSES

ENDOGENIC PROCESSES

EARTH SURFACE

RATIONALE OF THE STUDY

THE COASTAL AREA OF BANGLADESH HAS BEEN CHANGED SIGNIFICANTLY DURING THE GEOLOGICAL TIME.

THE NATURE AND THE EXTENT OF SUCH CHANGES WILL HELP TO UNDERSTAND THE FUTURE CONDITION OF THAT AREA AND HOW THIS WILL AFFECT THE LIVES OF PEOPLE.

THE AIM OF THIS STUDY IS TO EXPLORE THE GEOMORPHOLOGICAL EVOLUTION OF TEKNAF PENINSULA.

OBJECTIVES

TO KNOW THE MAJOR GEOMORPHOLOGICAL TYPES OF THE

AREA

TO KNOW THE CHANGES OF THE BATHYMETRY OF THE

AREA

TO KNOW THE LITHOLOGICAL SEQUENCES OF THE AREA

TO UNDERSTAND THE EVOLUTION HISTORY OF THE STUDY

AREA FROM THE FORMER EVIDENCES

METHODOLOGY

SATELLITE IMAGERY

GIS

STUDY OF BATHYMETRIC

CHART

FIELD WORK:

VEGETATION SURVEY

BORING

LITHOLOGICAL SECTION

TOPOGRAPHIC SURVEY

BATHYMETRIC SURVEY

OBSERVATION

DATA PRESENTATION

GEOMORPHOLOGICAL DATA

(REF: GROUP A)

FEATURES AREA (SQUARE KM)

PERCENTAGE (%)

ALLUVIAL PLAIN 33.350198 59.5

HILL 0.889527 1.5

PIEDMONT 0.922201 1.6

MUD FLAT 1.305136 2.2

RIVER 1.375803 2.3

ROAD (LENGTH) 238.149796 -

SALT MARSH 0.115901 0.2

SAND DUNE 0.534496 0.9

SANDY BEACH 2.658234 4.6

SPIT BAR 0.348413 .05

TIDAL FLAT 15.376546 27.5

WATER BODIES 0.010943 0.02

DATA PRESENTATION

LANDUSE DATA

( REF: GROUP B)

Name of the Features Percentage (%)

Forest (Plain Land, Hilly & Tidal) 16.87%

Agriculture 45.47%

Settlement 7.24%

Water bodies (River & Others) 2.59%

Barren (Hill, Sandy sea beach & Tidal Flat)

13.78%

Salt cultivated land & Spit Bar 13.07%

DATA PRESENTATION

BATHYMETRY DATA

(REF: GROUP C)

DATA PRESENTATION

BOTTOM TOPOGRAPHY OF THE SHELF AREA, 1982

BOTTOM TOPOGRAPHY OF THE SHELF AREA, 2009

DATA PRESENTATION

BATHYMETRY DATA

(REF: GROUP C)

DATA PRESENTATION

DATA PRESENTATION

LITHOLOGICAL DATASOIL PROFILE OF EASTERN PART OF THE EMBANKMENT AND AGRICULTURAL LAND

DIFFERENT SOIL LAYERS

DATA PRESENTATION

lost lost

LITHOLOGICAL DATA

DATA PRESENTATION

SOIL PROFILE OF WESTERN PART OF THE TEKNAF SEA BEACH

DATA PRESENTATION

ANALYSIS OF THE DATA

MORPHOLOGICAL EVIDENCES

THE PRESENCE OF HILL SHOWS

TECTONIC INFLUENCE.

PIEDMONT AND ALLUVIAL PLAIN

IS FORMED BY FLUVIAL

PORCESS

THE TIDAL FLAT, SALT MARSH,

SPIT BAR ETC. ARE FORMED BY

OCEANOGRAPHIC PORCESS

(REF: GROUP A)

ANALYSIS OF THE DATA

CONTINUOUS ELONGATED

BEACH ON THE EASTERN SIDE

OF THE PENINSULA.

THE ALLUVIAL PLAIN OF

SHAHPURI ISLAND IS

SEPARATED FROM THE ALLUVIAL

PLAIN OF THE MAINLAND ISLAND

BY AN EXTENSIVE TIDAL FLAT

THE PRESENCE OF THE SPIT

BAR

(REF: GROUP A)

MORPHOLOGICAL EVIDENCES

SUCCESSIVE LAYERS SAND, SILT AND CLAY

DEPOSTION SUGGESTS STEADY PROCESS OF

SEDIMENTATION

RENEWED DEPOSITION OF SAND OVER CLAY

REPRESENTS RAPID ENVIRONMENTAL CHAGE

A THICK LAYER INDICATES LONG TERM

SEDIMENTATION PROCESS

A THIN LAYER OF SEDIMENT REPRESENTS SHORT

TERM DEPOSITIONAL PROCESS

( REF: GROUP B)

LITHOLOGICAL EVIDENCES

ANALYSIS OF THE DATA

( REF: GROUP B)

ANALYSIS OF THE DATA

FOR BEACH AREA

¤ COMBINATION OF BOREHOLE AND SECTION DATA SHOWS

¤ THICKLAYER OF SANDY SOIL OVERLAIN BY VERY THIN

CLAYEY SILT AND PRESENCE OF CONSIDERABLE AMOUNT

OF ORGANIC MATTER INDICATES:

i. DEPOSITION OF SAND IN HIGH ENERGY ENVIRONMENT

ii. DEPOSITION OF FINE GRAINED SEDIMENTS POSSIBLY

DUE TO TIDAL INFLUENCE/ EROSION

iii. PRESENCE OF MARSHY ENVIRONMENT IN PAST

LITHOLOGICAL EVIDENCES

FOR SHAHPARIR DWIP

LITHOLOGICAL EVIDENCES

COMBINATION OF BOREHOLE AND SECTION DATA

SHOWS

SAND OVERLAIN BY CLAYEY SILT

WHICH IS AGAIN OVERLAIN BY CLAYEY AND SILTY

TOPSOIL.

THIS INDICATES:-

i. CHANGES IN DEPOSITIONAL ENVIRONMENT

ii. SAND LAYER FORMED WHEN CLIMATE WAS

POSSIBLY WET

iii. DECREASE IN ENERGY OF THE ENVIRONMENT

iv. SEA LEVEL CHANGE

SIGNIFICANT CHANGES

IN THE UNDERWATER

TOPOGRAPHY OF THE

SHELF.

ALTERNATING BANDS OF

EROSIONAL AND

DEPOSITIONAL AREAS.

(REF: GROUP C)

BATHYMETRIC EVIDENCES

ANALYSIS OF THE DATA

ANALYSIS OF THE DATABATHYMETRIC EVIDENCES

Cross Profile for the shelf area from 1982 - 2009

• Depth of the ocean has increased on average

• Top of the underwater shoals have been eroded away

• This sediments have accumulated in the adjacent low areas of the shelf.

LANDUSE OF TEKNAF PENINSULA HAS

BEEN INFLUENCED BY ITS

GEOMORPHOLOGICAL CHARACTERISTICS.

THE HILLY AREA AND TIDAL FLAT AREA ARE

BARREN LAND. THE TIDAL FLAT BETWEEN

THE SOUTHERN AND NORTHERN ALLUVIAL

PLAIN IS USED FOR SALT CULTIVATION.

ALLUVIAL PLAINS ARE USED FOR

SETTLEMENT AND AGRICULTURE.

THE CHANGES IN LAND USE SIGNIFICANTLY

CHANGES THE MORPHOLOGICAL

CHARACTERISTICS OF THE PENINSULA

( REF: GROUP B)

ANALYSIS OF THE DATA

LANDUSE EVIDENCES

THERE IS VARIATION IN VEGETATION COMPOSITION

ACCORDING TO GEOMORPHOLOGIC CHARACTERISTICS.

THE SAND DUNES OF THE BEACH AREA ARE MOSTLY

OCCUPIED BY HERB, SHRUB INCLUDING CLIMBING SPECIES.

THE SMALL SHRUBS AND HERBS ARE MOST COMMON

VEGETATION AND PALM SPECIES CONSTITUTE THE LARGER

PART OF THE TREE SPECIES.

THE NATURAL VEGETATION IS DISTURBED BY HUMAN

INTERVENTION. VARIOUS HOMESTEAD FORESTS HAVE BEEN

FOUND.

MANGROVE FORESTS ARE FOUND ALONG THE EASTERN SIDE

OF THE PENINSULA BECAUSE OF THE TIDAL AREA ALONG THE

NAAF ESTUARY

(Ref: Group A)

ANALYSIS OF THE DATA

VEGETATION EVIDENCES

OCEANOGRAPHIC PROCESSES:

PROCESSES OF GEOMORPHOLOGICAL EVOLUTION

OCEANOGRAPHIC PROCESS

TIDAL MOVEMENTS

CURRENTS

STREAM OUTFLOW

WAVE ACTION

CLIMATIC PROCESS

PROCESSES OF GEOMORPHOLOGICAL

EVOLUTION

LONG TERM CHANGES IN SEA-LEVEL

THE MAIN REASONS BEHIND SEA LEVEL RISE ARE THE THERMAL EXPANSION OF OCEAN WATER

OTHER REASONS AERTHE GLACIERS AND ICE-CAPS MELTING, WITHDRAWAL OF GROUND WATER ETC.

HOLOCENE SEA LEVEL RISE ALONG THE EASTERN BANK OF THE COX’S BAZAAR & TEKNAF IS ACCOMPANIED BY COASTAL EROSION

SOURCE: SARWAR, 2005

PROCESSES OF GEOMORPHOLOGICAL EVOLUTION

TECTONIC PROCESSES

PROCESSES OF GEOMORPHOLOGICAL EVOLUTION

PLATE MOVEMENT

LOW TO MEDIUM INTENSITY EARTHQUAKES SUGGESTS THAT THE AREA IS TECTONICALLY ACTIVE. IT IS KNOWN THAT THE INDIAN PLATE IS SUBDUCTING UNDER THE EURASIAN AND BURMESE PLATES. AS A RESULT, THE COASTAL PLAIN FRINGING THE TERTIARY HILLS HAVE BEEN UNDERGOING UPLIFTMENT IN SOME PART WHILE SUBSIDENCE IN OTHER PARTS.

UPLIFTMENT AND SUBSIDENCE

• A SERIES OF STEP-FAULTS IN THE SOUTHERN PART OF TEKNAF SHOWS CHARACTERISTICS OF A DOWNTHROWN BLOCK. THE SUDDEN INCREASE IN SEDIMENT THICKNESS IN THE SOUTHERN PART SUGGESTS EXISTENCE OF ANOTHER BLOCK.

HUMAN INTERVENTION

HUMAN ACTIVITIES LIKE MINING,

CONSTRUCTION, AGRICULTURE AND WATER

MANAGEMENT PROJECTS AFFECT DIFFERENT

GEOMORPHIC PROCESSES. ALONG THE COAST,

EXCESSIVE LOGGING, DIRECT LAND

RECLAMATION FOR AGRICULTURE,

AQUACULTURE, SALT PONDS, PORT BUILDING

AND SHRIMP FARMING AGGRAVATE COASTAL

EROSION.BESIDES ACTIVITIES WITHIN RIVER

CATCHMENTS/WATERSHEDS LIKE- DAM

CONSTRUCTION AND RIVER DIVERSION CAUSE

REDUCTION OF SEDIMENT SUPPLY TO THE

COAST AND ULTIMATELY CONTRIBUTES TO

COASTAL EROSION

PROCESSES OF GEOMORPHOLOGICAL

EVOLUTIONSALT FARMING

SHRIMP FARMING

DRIED FISH

PROCESSES OF GEOMORPHOLOGICAL EVOLUTION

CONCLUSIONS

THE SHAHPURI ISLAND WAS ONCE SEPARATED FROM THE MAINLAND WHICH LATER WAS FILLED UP BY

SEDIMENTATION FROM THE NAAF RIVER AND TIDAL ACTION.

THE AREA IS UNDERGOING SIGNIFICANT CHANGES DUE TO ACCRETION AND EROSION AS WELL AS HUMAN INTERVENTION.

THAT THE RATE OF EROSION OUTWEIGHS ACCRETION IN OUR STUDY AREA.

CONCLUSIONS

REFERENCES

AHMED, S. 2005. RECENT CHANGES IN THE COASTAL REGION OF

BANGLADESH: STUDIES IN GEOMORPHOLOGY, UNPUBLISHED MS

THESIS, DEPT. OF GEOGRAPHY & ENVIRONMENT, UNIVERSITY OF

DHAKA.

PHILLIPS, J.D. 2006. EVOLUTIONARY GEOMORPHOLOGY:

THRESHOLDS AND NONLINEARITY IN LANDFORM RESPONSE TO

ENVIRONMENTAL CHANGE. TOBACCO ROAD RESEARCH TEAM,

DEPARTMENT OF GEOGRAPHY, UNIVERSITY OF KENTUCKY, USA.

SARWAR, MD. G.M., 2005. IMPACTS OF SEA LEVEL RISE ON THE

COASTAL ZONE OF BANGLADESH. UNPUBLISHED MS THESIS, DEPT.

OF INTERNATIONAL MASTERS PROGRAMME IN ENVIRONMENTAL

SCIENCE LUND UNIVERSITY, SWEDEN.

GOOGLE IMAGES.

THANK YOU FOR YOUR KIND ATTENTION