A humid, low-lying, alluvial region, Bangladesh
is composed mainly of the great combined delta of the Ganges,
Brahmaputra, and Meghna rivers.
Except for the Chittagong
Hills along the Myanmar
border, most of the country is no more than 300 ft (90 m)
above sea level. Bangladesh is laced with numerous streams,
distributaries, and tidal creeks, forming an intricate network
of waterways that constitutes the country's chief transportation
system. Along the southwestern coast is the Sundarbans,
a mangrove swamp area with numerous low islands.
| Location:
|
Southern
Asia, bordering the Bay of Bengal, between Burma and
India |
| Geographic
Coordinates: |
24
00 N, 90 00 E |
| Map
References: |
Asia
|
| Area
: total: |
144,000
sq km |
| Land:
|
133,910
sq km |
| Water: |
10,090
sq km |
| Area
Comparative: |
slightly
smaller than Iowa |
| Land
Boundaries: |
total:
4,246 km |
| Border
countries: |
Burma
193 km, India 4,053 km |
| Coastline: |
580
km |
| Maritime
Claims: |
contiguous
zone: 18 NM |
| Continental
shelf: |
up
to the outer limits of the continental margin |
| Exclusive
economic zone: |
200
NM |
| Territorial
sea: |
12
NM |
| Climate:
|
tropical;
mild winter (October to March); hot, humid summer
(March to June); humid, warm rainy monsoon (June to
October) |
| Terrain:
|
mostly
flat alluvial plain; hilly in southeast |
| Elevation
Extremes: |
lowest
point: Indian Ocean 0 m |
| Highest
point: |
Keokradong
1,230 m |
| Natural
Resources: |
natural
gas, arable land, timber, coal |
| Land
Use: |
arable
land: 61% |
| Permanent
crops: |
3% |
| Other:
|
36%
(1998 est.) |
| Irrigated
Land: |
38,440
sq km (1998 est.) |
| Natural
Hazards: |
Droughts,
cyclones; much of the country routinely inundated during
the summer monsoon season |
The physiography of Bangladesh
is characterized by two distinctive features: a broad deltaic
plain subject to frequent flooding, and a small hilly region
crossed by swiftly flowing rivers. The country has an area
of 144,000 square kilometers and extends 820 kilometers north
to south and 600 kilometers east to west. Bangladesh is bordered
on the west, north, and east by a 2,400-kilometer land frontier
with India and, in the southeast, by a short land and water
frontier (193 kilometers) with Burma.
On the south is a highly irregular deltaic coastline of about
600 kilometers, fissured by many rivers and streams flowing
into the Bay
of Bengal. The territorial waters of Bangladesh
extend 12 nautical miles, and the exclusive economic zone
of the country is 200 nautical miles.
Roughly
80 percent of the landmass is made up of fertile alluvial
lowland called the Bangladesh Plain. The plain is part of
the larger Plain of Bengal, which is sometimes called the
Lower Gangetic Plain. Although altitudes up to 105 meters
above sea level occur in the northern part of the plain,
most elevations are less than 10 meters above sea level;
elevations decrease in the coastal south, where the terrain
is generally at sea level. With such low elevations and
numerous rivers, water and concomitant flooding is a predominant
physical feature. About 10,000 square kilometers of the
total area of Bangladesh is covered with water, and larger
areas are routinely flooded during the monsoon season.
The
only exceptions to Bangladesh's low elevations are the Chittagong
Hills in the southeast, the Low Hills of Sylhet
in the northeast, and highlands in the north and northwest.
The Chittagong
Hills constitute the only significant hill system
in the country and, in effect, are the western fringe of
the northsouth mountain ranges of Burma and eastern India.
The Chittagong Hills rise steeply to narrow ridge lines,
generally no wider than 36 meters, 600 to 900 meters above
sea level. At 1,046 meters, the highest elevation in Bangladesh
is found at Keokradong, in the southeastern part of the
hills. Fertile valleys lie between the hill lines, which
generally run north-south. West of the Chittagong Hills
is a broad plain, cut by rivers draining into the Bay of
Bengal, that rises to a final chain of low coastal hills,
mostly below 200 meters, that attain a maximum elevation
of 350 meters. West of these hills is a narrow, wet coastal
plain located between the cities of Chittagong in the north
and Cox's Bazar in the south.
About
67 percent of Bangladesh's non urban land is arable. Permanent
crops cover only 2 percent, meadows and pastures cover 4
percent, and forests and woodland cover about 16 percent.
The country produces large quantities of quality timber,
bamboo, and sugarcane. Bamboo grows in almost all areas,
but high-quality timber grows mostly in the highland valleys.
Rubber planting in the hilly regions of the country was
undertaken in the 1980s, and rubber extraction had started
by the end of the decade. A variety of wild animals are
found in the forest areas, such as in the Sundarbans on
the southwest coast, which is the home of the worldfamous
Royal Bengal Tiger. The alluvial soils in the Bangladesh
Plain are generally fertile and are enriched with heavy
silt deposits carried downstream during the rainy season.
 |
Bangladesh
has a tropical monsoon climate with a distinct dry season
in the winter. It receives an average annual rainfall of
80 in. (203 cm), with most falling during the summer monsoon
period; the Sylhet district in the northeast is the wettest
part of the country, having an annual average rainfall of
140 in. (356 cm). The low-lying delta region is subject
to severe flooding from monsoon rains, cyclones, and tidal
waves that bring major crop damage and high loss of life.
The cyclones of 1970 and 1991 and the monsoon floods of
1998 were particularly devastating.
Bangladesh
has a subtropical monsoon climate characterized by wide
seasonal variations in rainfall, moderately warm temperatures,
and high humidity. Regional climatic differences in this
flat country are minor. Three seasons are generally recognized:
a hot, humid summer from March to June; a cool, rainy monsoon
season from June to October; and a cool, dry winter from
October to March. In general, maximum summer temperatures
range between 32°C and 38°C. April is the warmest
month in most parts of the country. January is the coldest
month, when the average temperature for most of the country
is 10°C.
Winds
are mostly from the north and northwest in the winter, blowing
gently at one to three kilometers per hour in northern and
central areas and three to six kilometers per hour near
the coast. From March to May, violent thunderstorms, called
northwesters by local English speakers, produce winds of
up to sixty kilometers per hour. During the intense storms
of the early summer and late monsoon season, southerly winds
of more than 160 kilometers per hour cause waves to crest
as high as 6 meters in the Bay of Bengal, which brings disastrous
flooding to coastal areas.
Heavy
rainfall is characteristic of Bangladesh. With the exception
of the relatively dry western region of Rajshahi, where
the annual rainfall is about 160 centimeters, most parts
of the country receive at least 200 centimeters of rainfall
per year. Because of its location just south of the foothills
of the Himalayas, where monsoon winds turn west and northwest,
the region of Sylhet in northeastern Bangladesh receives
the greatest average precipitation. From 1977 to 1986, annual
rainfall in that region ranged between 328 and 478 centimeters
per year. Average daily humidity ranged from March lows
of between 45 and 71 percent to July highs of between 84
and 92 percent, based on readings taken at selected stations
nationwide in 1986.
About
80 percent of Bangladesh's
rain falls during the monsoon season. The monsoons result
from the contrasts between low and high air pressure areas
that result from differential heating of land and water.
During the hot months of April and May hot air rises over
the Indian subcontinent, creating low-pressure areas into
which rush cooler, moisture-bearing winds from the Indian
Ocean. This is the southwest monsoon, commencing in June
and usually lasting through September. Dividing against
the Indian landmass, the monsoon flows in two branches,
one of which strikes western India. The other travels up
the Bay of Bengal and over eastern India and Bangladesh,
crossing the plain to the north and northeast before being
turned to the west and northwest by the foothills of the
Himalayas.
Natural
calamities, such as floods, tropical cyclones, tornadoes,
and tidal bores--destructive waves or floods caused by flood
tides rushing up estuaries--ravage the country, particularly
the coastal belt, almost every year. Between 1947 and 1988,
thirteen severe cyclones hit Bangladesh, causing enormous
loss of life and property. In May 1985, for example, a severe
cyclonic storm packing 154 kilometer-per-hour winds and
waves 4 meters high swept into southeastern and southern
Bangladesh, killing more than 11,000 persons, damaging more
than 94,000 houses, killing some 135,000 head of livestock,
and damaging nearly 400 kilometers of critically needed
embankments. Annual monsoon flooding results in the loss
of human life, damage to property and communication systems,
and a shortage of drinking water, which leads to the spread
of disease. For example, in 1988 two-thirds of Bangladesh's
sixty-four districts experienced extensive flood damage
in the wake of unusually heavy rains that flooded the river
systems. Millions were left homeless and without potable
water. Half of Dhaka, including the runways at the Zia International
Airport--an important transit point for disaster relief
supplies--was flooded. About 2 million tons of crops were
reported destroyed, and relief work was rendered even more
challenging than usual because the flood made transportation
of any kind exceedingly difficult.
There
are no precautions against cyclones and tidal bores except
giving advance warning and providing safe public buildings
where people may take shelter. Adequate infrastructure and
air transport facilities that would ease the sufferings
of the affected people had not been established by the late
1980s. Efforts by the government under the Third Five-Year
Plan (1985-90) were directed toward accurate and timely
forecast capability through agrometeorology, marine meteorology,
oceanography, hydrometeorology, and seismology. Necessary
expert services, equipment, and training facilities were
expected to be developed under the United Nations Development
Programme.
Natural Regions
Most
of Bangladesh lies within the broad delta formed by
the Ganges and Brahmaputra rivers and is exceedingly
flat, low-lying, and subject to annual flooding. Much
fertile, alluvial soil is deposited by the floodwaters.
The only significant area of hilly terrain, constituting
less than one-tenth of the nation's territory, is
the Chittagong Hill Tracts District in the narrow
southeastern panhandle of the country. |
 |
There, on the border with Myanmar,
is Mowdok Mual (1,003 m/3,291 ft), the country's highest
peak. Small, scattered hills lie along or near the eastern
and northern borders with India. The eroded remnants of
two old alluvial terraces-the Madhupur Tract, in the north
central part of the country, and The Barind, straddling
the northwestern boundary with India-attain elevations of
about 30 m (about 100 ft). The soil here is much less fertile
than the annually replenished alluvium of the surrounding
floodplain.
Climate
The
climate of Bangladesh is of the tropical monsoon variety.
In all areas about 80 percent of the annual rainfall
typically occurs in the monsoon period, which lasts
from late May to mid-October. Mean annual precipitation
ranges from about 1,400 mm (about 55 in) along the
country's east central border to more than 5,080 mm
(200 in) in the far northeast. |
 |
In
addition to the normal monsoonal rainfall, Bangladesh is
subject to devastating cyclones, originating over the Bay
of Bengal, in the periods of April to May and September
to November. Often accompanied by surging waves, these storms
can cause great damage and loss of life. The cyclone of
November 1970, in which about 500,000 lives were lost in
Bangladesh, was one of the worst natural disasters of the
20th century.
More than 120,000 were killed and millions left homeless
in April 1991 when a powerful cyclone struck the coastal
areas in the Ganges delta. Tornadoes, which also accompany
the monsoon season, can cause harm to Bangladesh as well.
In May 1996 a tornado ripped through northern Bangladesh,
killing more than 440 people, injuring thousands, and destroying
at least 80 villages.
Bangladesh
has warm temperatures throughout the year, with relatively
little variation from month to month. January tends to be
the coolest month and May the warmest. In Dhaka the average
January temperature is about 19° C (about 66° F),
and the average May temperature is about 29° C (about
84° F).
Rivers and Lakes
Rivers are a prominent and important feature of
the landscape in Bangladesh. Some rivers are known by different
names in various portions of their course. The Ganges
(Ganga), for example, is known as the Padma below the point
where it is joined by the Jamuna River, the name given to
the lowermost portion of the main channel of the Brahmaputra.
The combined stream is then called the Meghna below its
confluence with a much smaller tributary of the same name.
In the dry season the numerous deltaic distributaries that
lace the terrain may be several kilometers wide as they
near the Bay of Bengal, whereas at the height of the summer
monsoon season they coalesce into an extremely broad expanse
of silt-laden water. In much of the delta, therefore, homes
must be constructed on earthen platforms or embankments
high enough to remain above the level of all but the highest
floods. In nonmonsoon months the exposed ground is pocked
with water-filled borrow pits, or tanks, from which the
mud for the embankments was excavated. These tanks are a
chief source of water for drinking, bathing, and small-scale
irrigation.
The rivers of Bangladesh mark both the physiography of the
nation and the life of the people. About 700 in number,
these rivers generally flow south. The larger rivers serve
as the main source of water for cultivation and as the principal
arteries of commercial transportation. Rivers also provide
fish, an important source of protein. Flooding of the rivers
during the monsoon season causes enormous hardship and hinders
development, but fresh deposits of rich silt replenish the
fertile but overworked soil. The rivers also drain excess
monsoon rainfall into the Bay of Bengal. Thus, the great
river system is at the same time the country's principal
resource and its greatest hazard.
1
Jamuna-Brahmaputra
The Jamuna-Brahmaputra is 292 kilometers long and extends
from northern Bangladesh to its confluence with the Padma.
2 Padma-Ganges
The second system is the Padma-Ganges, which is divided
into two sections: a 258-kilometer segment,
3 Surma-Meghna
The third network is the Surma-Meghna system, which courses
from the northeastern border with India to Chandpur, where
it joins the Padma.
4 Padma-Meghna
This mighty network of four river systems flowing through
the Bangladesh Plain drains an area of some 1.5 million
square kilometers.
5
Karnaphuli.
A fifth river system, unconnected to the other four, is
the Karnaphuli.
Vegetation and Animal Life
With the exception of the Chittagong Hill Tracts District,
portions of the Madhupur Tract, and the Sundarbans (a great
tidal mangrove swamp in the southwestern corner of the country),
few extensive forests remain in Bangladesh, the forested
and wooded area amounting to about one-eighth of the total
area. Broadleaf evergreen species characterize the hilly
regions, and deciduous trees, such as acacia and banyan,
are common in the drier plains areas. Commercially valuable
trees in Bangladesh include sundari (hence the name Sundarbans),
gewa, sal (mainly growing in the Madhupur Tract), and garyan
(in the Chittagong Hill Tracts District). Village groves
abound in fruit trees (mango and jackfruit, for instance)
and date and areca (betel) palms. The country also has many
varieties of bamboo.
Bangladesh
is rich in fauna, including 109 indigenous species of mammals,
684 types of birds, 119 kinds of reptiles, 19 different
amphibians, and 200 varieties of marine and freshwater fish.
The rhesus monkey is common, and gibbons and lemurs are
also found. The Sundarbans
area is one of the principal remaining domains of the Bengal
tiger, and herds of elephants and many leopards
inhabit the Chittagong Hill Tracts District. Other animals
living in Bangladesh include mongoose, jackal, Bengal fox,
wild boar, parakeet, kingfisher, vulture, and swamp crocodile.
Mineral Resources
The mineral endowment of Bangladesh is meager. The principal
energy resource, natural gas, is found in several small
fields in the northeast. There is a coalfield in the northwest
and large peat beds underlie most of the delta. Limestone
and pottery clays are found in the northeast.
 |
| Administration |
| |
|
| Slope
% |
| |
Undefined |
| |
0
- 2 % |
| |
2
- 5 |
| |
5 - 8 |
| |
8
- 16 |
| |
16 - 30 |
| |
30
- 45 |
| |
45 |
| |
Water |
|
