This slide is about the natural hazards of Bangladesh

1. Submitted By
Jarin Fardous Jakia
&
Atif Mukith Choudhury
Masters’ 1st semester (Session: 2020-21)
Dept’ of Geography and Environment, SUST
Natural Hazards of Bangladesh
Submitted To
Md. Bahuddin Sikder
Assistant Professor
Dept. of Geography and Environment,
Shahjalal University of Science and Technology, Sylhet.

2. Here Inculded..
Seasonal
Distribution of the
Hazards of
Bangladesh
Major Natural
Hazards of
Bangladesh
Causes of the
Natural Hazards
Affected Areas
2

3. Different Types of Natural Hazards in
Banglaesh
Atmospheric Hazards (High Risk)
• Storm
• Cyclone
Exogenic Hazards (High Risk)
• Flood
•Riverbank Erosion
•Coastal Erosion
Endogenic Hazards (Low risk)
Natural hazards can be identified into
three broad groups-
• Atmospheric Hazards, caused by
atmospheric processes
• Exogenic Hazards, caused by the
earth surface processes
• Endogenic Hazards, caused by
internal earth processes
On many occasions there are overlaps
between these different events.
• Groundwater
Contamination
• Soil Erosion etc.
• Earthquake
• Drought
• Tornado etc.
3

4. Seasonal Distribution of the Hazards of Bangladesh
• Flood
• River Erosion
• Land slide
• Cyclone
• Tornado
•Thunder strom
•Tornado
•Cyclone
•Heat Wave
•Drought
• Cold wave
• Abnormal
Dryness
Winter
Hazards
Pre-
monsoon
Hazards
Moonsoon
Hazards
Post-
monsoon
Hazards
4

5. 5

6. 6

7. • winds rotate inwardly to an area of low
atmospheric pressure
• Wind from south-east side; 70% during
Spring and Summer
• Major Cyclones in Bangladesh:
 1991:138,882 people died; 148,058
injured
 2007: 3,404 people died; 1,004 still
missing; 55,000 injured
 2009: 190 people died, 7,190 injured
Depression
Winds velocity up to
62 km/hr
Cyclonic Strom
Winds velocity
between 62-87
km/hr
Sever Cyclonic
Strom of Hurricane
Intensity
Winds velocity above
118 km/hr
Sever Cyclonic
Strom
Winds velocity
between 88-118
km/hr
Classification
(On the basis
of intensity)
7

8. • Geographic Location
 710 long coast line containing 19
districts and 47 upazilas of the country
• Coastal Configuration and Bathymetry
of the bay of Bangel
• Location of IICZ near Equator and it’s
shifting across the bay of Bengal
8

9. 9

10. • lack or shortage of precipitation
usually long period of time involving
50% less than the usual rainfall over a
month
• Causes :
 Less and uneven rainfall in dry season
and wet season
 Non-availability of surface water in dry
season
 Fluctuations of ground water table
Meterological
Hydrological
Agricultural
Scio-economic
4 types of droughts
10

11. 11

12. 12

13. 13

14. River Flood Rainfall Flood
Flash Flood Tidal Flood
River Flood
when a river overspills its banks; that is, when its
flow can no longer be contained within its
channel.
Tidal flooding
temporary inundation of low-lying areas,
especially streets, during exceptionally high
tide events (full and new moons)
Rainfall Flood
Caused by increases in both
extreme precipitation and total precipitation which
is mainly due to monsoon heavy rain
Flash floods
the rise in water is either during or within a few
hours of the rainfall that produces the rise.
14

15. • Floodplain of Brahmaputra-Jamuna
• The ganges-Padma river system
• The Meghna river system
• Haor basin of north-eastern region
• South-east hilly areas
Five floods during the last fifty years are
extensive and devastating and these are
the floods of 1955, 1974, 1987, 1988, and
1998
15

16. • Moonsoon climate
• Geographical location
• River Silt up
• Deforestation in the Headwater area
• Human Intervention
16

17. 17

18. 18

19. • about 5% of the total floodplain of
Bangladesh is directly affected by
riverbank erosion
• taking place in about 94 upazilas out of
496 upazilas/thanas of the country
• Ganges, Padma and Lower Meghna are
highly susceptible
• Riverbank erosion are of two types:
 Bank scour: removal of bank materials
by flowing water and carried sediment
 Mass failure: when sections of the
banks slides and topples into the water
stream
19

20. • Soil Type
Silt sized soil get eroded in higher rate
than clay or sand
• Sand Upliftment
1.1 billion tons of sediment are uplifted
yearly
• Stage of River
Three major river are in mature stage
• Geological Shape
Flat delta lands of Bangladesh offer a
little resistance to the hydraulic forces
• Wave action
20

21. 21

22. • Occur in the areas composed of
unconsolidated rock
• take place in both natural and
man-induced slopes
• Affected areas:
 Chattagram and ChattagramHill
Tracts
 Hill Ranges of Northeastern
Ranges of Northeastern Sylhet
 Hill along the Narrow Northern
Strip of Mymensingh
22

23. • Heavy Rainfall
• Hill Cutting and Deforestation
• Jhum and other forms of
cultivation on steep slopes
• Ungovernable Discharge by
River
• Unplanned Residence
Causes Adaptation
Common engineering
techniques:
• provision for surface
and subsurface
drainage
• removal of unstable
slope materials
• construction of retaining
walls
23

24. 24

25. 25

26. 26

27. 27

28. 28

29. • Refers to large and rapid
temperature drop over as short
period of time
• Causes:
 Geographical location
 Low temperature and low
humidity due to moonsoon
29

30. 30

31. 31

32. • Northern and central part of the
country
• Three zones:
 High Risk Zone (Sylhet,Mymensing,
Rangpur, Lalmonirhat and Kurigram)
 Medium Risk Zone
(Dhaka, Bogura, Dinajpur,Cummila etc)
 Low Risk Zone
(Khulna, Jossore, Barishal, Patuakhali)
32

33. the Cachar Earthquake
(1 October 1869, Jaintia
Hills, 7.5);
the Bengal Earthquake
(14 July 1885, Bogra
Fault, 7.0)
the Great Indian
Earthquake
(12 December 1897,
Shillong Plateau, 8.7)
Sreemangal Earthquake
(8 July 1918, Balisera
Valley of Sreemangal,
7.3)
the Bihar-Nepal
Earthquake (15 January
1934, Darbhanga, 8.3
the Dhubri
Earthquake
(3 July 1930,
Dhubri Town in
Assam, 7.1)
the Assam
Earthquake
(15 August 1950,
Aurunachal in
Assam, 8.5)
Sylhet Earthquake
(5 August 1997,
epicentre not
known, 6.00)
the Chittagong
Earthquake
(21 November 1997,
Indo-Bangladesh
Border, 6.00)
the Maheshkhali
Island Earthquake
(22 July 1999, West
of Maheshkhali
Island, 5.2)
33

34. • Bangladesh is situated adjacent to the plate margin of
India and Eurasia
• Numerous Faults
 The Dhauki Fault
 The Madhupur Fault
 The Sylhet—Assam Fault
 The Chittagong-Mayanmmar Fault
• Decreasing tendency of water under land
• Construction of large dams and vuildings, coal mining etc
34

35. 35

36. Thanks to All 
36