Physiography of Bangladesh

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INTRODUCTION
> Bangladesh belong to South Asia and lies
between 20 34 and 26 38 N, and 88 01 and 92
41 E. The area of the country is 147,570
square km with more than 700 km long
coastlines.
> About 80% of the land is flat,
intersected by numerous rivers and
their distributaries. The land area has a
general slope of 1 -2 from north to south .

WHAT IS PHYSIOGRAPHY?
Actually physiography is the holistic
discussion of the earth and its
characteristics.
Physiography is the terrain condition of a
tract of land.
In other word physiography reveals the
condition of surface of land. It deals about
the total feature of the crust. The
physiographic may vary from place to place.

PHYSIOGRAPHIC FEATURES OF
BANGLADESH
Bangladesh is a low level and vast plenty area.
Its Physiographic feature of is much diversified. It
is mentionable here that the Physiographic
feature of an area may change in pace of time due
to natural and artificial causes.
Physiographically Bangladesh can be
divided into 7 divisions. Each of these
divisions can be subdivided with distinguished
characteristics of its own.

PHYSIOGRAPHIC DIVISION OF
BANGLADESHi)

Hilly Regions

a) Chittagong Hill Tracts
b) Hill Ranges of Northeastern Sylhet
c) Hills along the Narrow Strip of
Sylhet and Mymensingh Districts
ii)

v) Flood Plains
a) Ganges Flood Plain
b) Atrai Flood Plain
c) Brahmaputra Jamuna Flood
Plain
d) Old Brahmaputra Flood Plain
e) Meghna Flood Plain

Pleistocene Uplands
a) Barind Tract in the north western

part
b) Madhupur Tract in the central part
c) Lalmai Hills
iii)

Tippera Surface

iv)

Tista Fan

vi) Delta Plain of the GangesBrahmaputra-Meghna Delta Complex
a) Active Delta
b) Inactive Delta
c) Tidal Delta
vii) Sylhet Depression and Inland
Marshes

PHISIOGRAPHIC MAP OF Bangladesh

HILLY REGIONS
Hilly areas occupy about 18% of Bangladesh.

Chittagong hill tracks:
High north-south striking hill ranges occupy wholly the districts of Chittagong,
Cox's Bazar and the three Hill Tract districts. The hills becomes higher towards
east reaching a maximum height of 1003 m.
The lowest ranges generally follow the eastern coast of the Bay of Bengal from
Feni River to Naf River and continue southwards across the Mayanmar border.
Most of Moheskhali Island belongs to this hilly area.
There is a narrow strip of coastal plain in the Chittagong District and a very
narrow strip of beach from Cox's Bazar to Teknaf, between the hills and the Bay
of Bengal. Chokoria Sundarban and the associated Mud Flat area is a small delta
of the Matamuhuri River.
Towards the east, the ranges get higher and the slope steeper until they reach the
highest hill range in the east that marks the boundary between Bangladesh,
Mayanmar and India.

HILLY REGIONS
Hills along the Narrow Strip of
Sylhet and Mymensingh Districts:
Some of the hill ranges of
the Chittagong and the Hill The narrow strip of discontinuous
low hill ranges extends from
Tract districts continue
Jaflong in the east to the
northward across the Indian
Brahmaputra River in the west.
State of Tripura and form the
These hills do not form
hill ranges of northeastern
continuous range, but constitute a
chain of circular and elongated
Sylhet region. These hill
hillocks separated by Holocene
ranges attain a much lower
alluvial
elevation and slope more
gently than their continuation valleys. Along the frontier of greater
in the Chittagong and the Hill Mymensingh these hills form
series of circular and elongated
Tract Districts.
hillocks.

Hill ranges of northern Sylhet:

A MAP
SHOWING
HILLY
REGIONS OF
BANGLADESH.

Pleistocene Uplands
The Pleistocene Uplands cover an area
of about 10% of Bangladesh.
Determination of the concealed
Pleistocene red clay that composes the
rock type in the immediate
surrounding of the Barind and the
Madhupur Tracts should increase their
Areas considerably.

3. The Madhupur Tract
The Madhupur Tract is
situated in the east of the
Barhmaputra River. It looks like a
chain of isolated circular to
elongated low hillocks standing at
a higher level than the surrounding
(a)The Barind Tract
flat alluvial plain and is affected by
The Barind Tract is located in the
a series of faults. This area of
west of the Brahmaputra River. It
about 4,058 sq. km. extends in
falls in the central part of north
Dhaka, Mymensingh and Tangail
Bangladesh and covers an area of
districts. The Madhupur Tract
7,680 sq. km in the Rajshahi division.
reaches a maximum height of 17 m
The area comprises of six northfrom sea level and is elevated
south elongated and isolated
during the same period as that of
exposures of reddish brown deposits.
the Barind Tract.
The Barind Tract is the product of
vertical movements of Pleistocene
period and reaches maximum height
of 20 m above modern flood plains.

A PHISIOGRAPHIC MAP
INCLUDING PLEISTOCENE
UPLANDS>>>>>>>>

Lalmai Hills
The Lalmai Hills are situated in the
Comilla district and are composed of
reddish
brown clay. The Lalmai Hills represent a
north-south elongated low hill range of
about 16
km long and about 2-3 km wide. It covers
an area of about 33 sq. km. The hill range
runs through the middle of Comilla district.
The average height is about 12 m that
reaches a maximum of about 47 meter
above the mean sea level. Comparable
with the Barind and Madhupur the Lalmai
Hills was uplifted at similar time and also
displays a dendritic drainage pattern.

TISTA FAN
• The Tista Fan is at the northwestern part of
Bangladesh. It is the extension of the Himalayan
piedmont plain that slope southward from a height
of 96 m to 33 m with a gradient of about 55 cm/km.
The region is covered by the piedmont sand and
gravel, which were deposited as alluvial fan of the
Tista, Mahananda and Karatoya rivers and their
distributaries issuing from the Terai area of the
foothills of Himalayas. There was a major shift in
the courses of these rives in 1887.

Tippera Surface
Tippera Surface The area between the Meghna floodplain in
the west and the TRIPURA HILLS in the east was uplifted in Early
Recent times. This physiographic unit consists of a Pleistocene
terrace in the east, ie the Lalmai terrace, and the postPleistocene deltaic plain of the Tippera surface. The latter is
made up of estuarine sediments of Early Recent age. The
present-day rectangular drainage pattern of this flat area was
artificially developed for irrigation purposes. The western edge
of the Tippera surface grades transitionally into the Meghna
floodplain. The Lalmai terrace, skirting the western slopes of
the Tripura hills, consists of red, mottled clay, of the Pleistocene
Madhupur clay type. Comparable to the Barind and Madhupur
tracts, the Lalmai terrace displays the typical dendritic drainage
pattern of all Pleistocene terraces. The surface is slightly
undulating, except the Lalmai hills, with elevations ranging
from 6 to 50m above MSL. It has been uplifted 1.22m to 1.83m
in relation to the adjacent floodplains during the Holocene time
(from 0.1 million years to the present).

FLOOD PLAINS OF BANGLADESH
The flood plains of
Bangladesh cover
approximately 40% of
Bangladesh.
The elevation of the
major part of the flood
plain ranges from 3 to
5 meters. The flood
plain covers the
central, north and
northeastern part of
the country.

MAJOR FLOOD PLAINS OF
BANGLADESH

The Ganges Flood Plain extends from the western border of the country, south of the Barind Tract, as
far east where it merges with the Jamuna Flood Plain.
The Meghna Flood Plain merges with the southern part of the Old Brahmaputra Flood Plain in the
northwest and with the Sylhet Depression in the north. Landform of the flood plain is characterized
by natural levees distributed in a mottled pattern which forms shallow depressions and small
ridges. The maximum height of the levees is 30 m above the sea level. There are numerous small
depressions (beels/haors) in the flood plain. The levee of the rivers gently slopes towards these
depressions. Silty clay, clay, sandy silt with local peat beds are the major constituents of the flood
plain area.
The Brahmapura-Jamuna Flood Plain is located between the Barind and Madhupur Tracts. Elevation of
this surface is 29 m in the north and about 6 m in the south.
The old course (OLD BRAHMAPUTRA) between Bahadurabad and Bhairab shrank through silting into a small
seasonal CHANNEL only two kilometre wide. The old river had already built up fairly high levees on
either side over which the present river rarely spills. The Old Brahmaputra floodplain stretching
from the southwestern corner of the Garo Hills along the eastern rim of the Madhupur Tract down
to the Meghna exhibits a gentle morphology composed of broad ridges and depressions.
Atrai flood plains situated on almost west part of Bangladesh exactly under the Barind Tract and above
the Ganges Flood Plain. Atrai flood plain joins with Ganges Flood Plain togards the Brahmaputra
Flood plain.

MAP SHOWING MAJOR FLOOD PLAINS OF
BANGLADESH

DELTAIC PLAIN OF GANGESBrahmaputra-Meghna Delta Complex
The Active and the Inactive Delta
The Delta Complex covers about 32% of Bangladesh. The area south
of a line drawn from Ganges -Padma as far as the lower course of the
Feni river in the southeast belongs to the delta of the Ganges,
Brahmaputra and Meghna river. The Ganges is the greatest builder of
the delta (70-80%). The Ganges delta located in the south of the Barind
and Madhupur Tract also includes part of West Bengal. The Bangladesh
portion of the delta occupies about 46,620 sq. km. In the southwest, a
part of the delta has been classified as the inactive delta but the major
part in the south and southeast is very active. The elevation of the delta is
about 15 to 20 m from the sea level in the northwest and 1 to 2 m in the
south. The elevation increases within the upper reaches of the delta.
Many swamps (depressions) have developed in the substantial part of the
delta. Clay, silt clay and occasionally peat are the major constituent of
the delta plain.

The present Delta is a
combination of three
deltas, namely the
1.Ganges delta
2.The Old
BrahmaputraMeghna delta
3.The GangesJamuna (the present
Brahmaputra)Meghna Delta.

TIDAL DELTAIC PLAIN
This is the southern part of the Delta plain.
This area is tide dominated and is considered
as the active part of the delta. The landforms
are characterized by tidal low land with
Weakly developed natural levees distributed
in an irregular pattern. Numerous rivers,
channels, tidal creeks have criss-crossed the
area. Swamps and depressions are also present
in the area. Estuarine deposits of silt, silty
clay dominate sin this area. Mangrove swamps
of the Sundarban and many salt fields and
shrimp culture farms have developed in the
area. The landforms in the area are temporal as
they are changing due to the cyclones and
other natural calamities.

Sylhet Depression and Inland
Marshes
The Sylhet Depression is a tectonic basin subsiding at a
very fast rate and is bounded by the hills of frontier
strip of Sylhet and Netrokona Districts in the north
and the northeastern Sylhet Hills in the east.
Numerous lakes (beels) and large swamps (haors)
cover the saucer shaped area of about 7,250 sq. km.
The elevation of the central part of the depression is
about 3 m above the sea level. The inland marshes are
found scattered all over the country. Most of them are
back swamps, oxbow lakes and abandoned channels
formed due to the changes in the courses of the rivers.

MAPS SHOWING SYLHET
DIPRESSION

A
TOTAL
PHISI
OGRA
PHIC
MAP
OF
BANG
LADES
H
WITH
LEVEL
S

Physiography of Bangladesh

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