Climate Change and Health of Sundarbans

By

Ahmadul HassanDirector, R& D and Training Division

Email: ahassan@cegisbd.comDate: April 14, 2011

Kolkata, India

A public trust under the Ministry of Water Resources

Launch of Sundarbans Pavilion

World Wildlife Fund

Ganges Basin

Brahmaputra Basin

Meghna Basin

Background Bangladesh occupies only 7% of the combined catchment area of the

Ganges-Brahmaputra-Meghna river basin, But the country has to drain out 92% of the flow into the Bay of Bengal. Too much water in the monsoon and too little water in the dry season

2

Forest Ecosystem in Bangladesh

Types of Forest Area (Sq. km)

Tropical evergreen and semi-evergreen Forest 6,700

Natural Mangrove Forest and Plantation 6,000

Tropical moist deciduous Forest 12,00

Tropical evergreen and semi-evergreen forest are mainly hill forest

The tropical moist deciduous forests commonly known as the plain land ‘Sal’ forest

The Sundarbans is the largest single tract of natural mangrove forest in the world covers 40% of total forest area of Bangladesh

3

Sundarbans

• Biodiversity– 350 species of vascular plants, – 250 fishes and– 300 birds– 42 species of mammals are available in

this mangrove forest

• It is the homeland of world famous Royal Bengal Tiger

• In 1997, UNESCO declared it as a world heritage sight

• Sundarbans covers an area of 10,000 km2 of which about 6,000 km2 are in Bangladesh

4

Climate Change in Bangladesh Annual average temperature will increase by

0.78°C in 2030 and 1.6°C in 2050 for scenario B1

Mean annual precipitation will increase by 6.3% in 2030 and 8.4% in 2050 for scenario B1

Sea level will rise about 27 cm by 2050.

Total saline water area will increase to 17.5% (1 ppt) and 24% (5 ppt) by 2050.

47 % area in 2025 and 45% area in 2050 will be in no stress condition 5

Aim of this Research

The aim of this research is to find out what are the physical factors which

support good health for the Sundarbans

6

Forest Health Evaluation

ParametersDevelopment of

forest health evaluation criteria

and parameters

Expert

Consultation

Forest cover Information

Evaluation ofForest Health Index

(Very Good, Good, Poor)

Literature Review

FloodingSalinity

ConcentrationGeomorphic

featureDrainagedensity

SLR

Scenario

Adaptation

Options

ParametersDevelopment of

forest health evaluation criteria

and parameters

Expert

Consultation

Forest cover Information

Evaluation ofForest Health Index

(Very Good, Good, Poor)

Literature Review

FloodingSalinity

ConcentrationGeomorphic

featureDrainagedensity

SLR

Scenario

Adaptation

Options

7

Topographical Distribution of Sundarbans Elevation (m)

0.20%2.83%

10.49%

20.53%

28.79%

22.88%

10.44%

2.94%0.81%

0%

5%

10%

15%

20%

25%

30%

35%

0.0 - 0.5 0.5 - 1.0 1.0 -1.5 1.5 -2.0 2.0 - 2.5 2.5 - 3.0 3.0 -3.5 3.5 -4.0 > 4.0

Elevation (m,PWD)

 

DEM

70% of the land goes under water in regular tidal flooding and

Almost 85% of the land goes under water during high tide in the monsoon season. 8

Changing Pattern in Distribution of Sundri and Gewa from 1992 to 2001

9

Changing Pattern in Distribution of Goran and Gewa from 1992 to 2001

10

Forest Cover Using RS

1992 1995

2001-04-05 DoF 1995

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Forces Increased SalinitySedimentationChange in InundationTemperatureAnthropogenic Factors (e.g. increased population in buffer zone, illegal extraction, encroachment)

Forest vegetations

•Sundri- Gewa

•Gewa-Sundri

•Sundri

•Goran-Gewa

• --------

Habitat

•Mammals

•Reptiles

• Birds

• Amphibians

•-------------

Why have the Changes Occurred

12

Sundri

0

100

200

300

400

500

Less Moderate Strong

Salinity

De

nsi

ty (

no

s/h

ec)

Gewa

0

100

200

300

400

500

Less Moderate Strong

Salinity

De

nsi

ty (

no

s/h

ec)

Keora

050

100150200250300350400450

Less Moderate Strong

Salinity

De

nsi

ty (

no

s/h

ec)

Impact of Salinity on Forest Density

Low < 15 pptModerate 15-25 pptHigh >25 ppt

13

Sundri

3

6

9

12

Inu

nd

atio

n M

on

ths

Survival Performance

Kakra

3

6

9

12

Inu

nd

atio

n M

on

ths

Survival Performance

Gewa

3

6

9

12

Inu

nd

atio

n M

on

ths

Survival Performance

Survival Performance Under Different Flooding Condition

14

Forest: Growth Index Modelling

Mu

dfla

ts (

slo

pe)

High-tide water level

Low-tide water level

Rid

ges

or

leve

es

Back-swamps or basins

Ma

in r

ive

r ch

anne

l hoda

nol khagra

golpata

keora/baen goran

Gewa

sundari

hargoza

Present Future

Sundri

15

Suitability of Sundri (Heritiera fomes)

Drainage Density :Low

Inundation

Salinity Low Medium High

Low Good Good Poor

Medium Good Poor Poor

High Poor Poor Poor

Drainage Density :High

Inundation

Salinity Low Medium High

Low Very Good Very Good Good

Medium Good Good Poor

High Poor Poor Poor16

Suitability of Gewa (Excoecaria agallocha)Drainage Density :Low

Inundation

Salinity Low Medium High

Low Good Very Good

Good

Medium Good Good Good

High Good Good Poor

Drainage Density :High

Inundation

Salinity Low Medium High

Low Good Very Good Good

Medium Very Good Good Good

High Good Good Poor 17

Suitability of Goran (Ceriops decanda)

Drainage Density :Low

Inundation

Salinity Low Medium High

Low Poor Poor Poor

Medium Good Good Poor

High Very Good Good Poor

Drainage Density :High

Inundation

Salinity Low Medium High

Low Poor Poor Poor

Medium Good Good Poor

High Very Good Good Poor18

Plant Type – Sundari – Health Index Under Different SLR Scenarios

Suitability of Sundri in SLR Base scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

Suitability of Sundri in SLR 32 cm scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

Suitability of Sundri in SLR 88 cm scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

19

Suitability of Gewa in SLR Base scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

Suitability of Gewa in SLR 32 cm scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

Suitability of Gewa in SLR 88 cm scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Perc

enta

ge o

f Su

itabi

lity

Very Good Good Poor

Plant Type – Gewa – health Index Under Different SLR Scenarios

20

Suitability of Goran in SLR Base scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Per

cen

tag

e o

f S

uita

bili

ty

Very Good Good Poor

Suitability of Goran in SLR 32 cm scenario

0

20

40

60

80

100

Block_A Block_B Block_C

Block in Sundarban

Per

cen

tag

e o

f S

uita

bili

tyVery Good Good Poor

Plant Type – Goran – health Index Under Different SLR Scenarios

21

Dominant Plant Distribution Under Different SLR condition

0

10

20

30

40

50

60

70

Very Good Good Poor

Sundri Dominant

Percentage SLR-base Percentage SLR-32cm Percentage SLR-88cm 22

Plant Diversification in Sundarbans

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Conclusions

• Due to SLR effects the area of sundarban will change the species composition.

• The “Sundri” will eventually be reduced to almost half from the present extent, whereas “Goran” area will increase and become the dominant forest species.

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Suggestion to Improve the Degraded Ecosystem

• To protect the river dependent ecosystem, we have to keep the river system alive

• Natural resource should not be used at a greater rate than it’s regeneration capacity

• Ecosystem has not political boundaries. So, a holistic approach is needed to protect the ecosystem.

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User

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Thank you