l 02-bangladesh-geographical & environmental settings

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Bangladesh: Geographical & Environmental Settings-

Location, Climate,

River systems, and

Floods in Bangladesh

Course Title: Bangladesh: Socio-Economic Perspective [Course No. BAN-201]

Course Teacher : Dr. M. Mizanur Rahman

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AimIn this section we will try to make Bangladesh familiar on several basic issues from its physical & environmental settings.

Objectives

To understand the geographical location/settings in Bangladesh

To focus the climate of Bangladesh

To highlight the river systems of Bangladesh

To illustrate the floods in Bangladesh

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Bangladesh: Geographical Settings

Bangladesh, on the northern coast of the Bay of Bengal, is surrounded by India, with a small common border with Myanmar in the southeast.

The country is low-lying riverine land traversed by the many branches and tributaries of the Ganges and Brahmaputra rivers.

Tropical monsoons and frequent floods and cyclones inflict heavy damage in the delta region.

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Bangladesh: Geographical Settings

Geographical Location:

Bangladesh is right on the Tropic of Cancer. More Precisely it is between 20035' and 26075' North of the Equator.

The 900 East longitude bisects the country, whose West-East spread is from 8803' to 90015' East.

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Bangladesh-Geographical Settings

GeographyArea: 147, 570 sq. km. (55,813 sq. mi.); about the size of Iowa.Cities: Capital--Dhaka (pop. 10 million). Other cities--Chittagong (2.8 million), Khulna (1.8 million), Rajshahi (1 million).Terrain: Mainly flat alluvial plain, with hills in the northeast and southeast.Climate: Semitropical, monsoonal.

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The World Map

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Most parts of Bangladesh are within 10 meters (33 ft) above the sea level, and it is believed that about 10% of the land would be flooded if the sea level were to rise by One (1) metre (3 ft).[29]

Because of this low elevation, much of this region is exceptionally vulnerable to seasonal flooding due to monsoons.

The highest point in Bangladesh is in Mowdok range at 1,052 metres (3,451 ft) in the Southeast of the country.

http://en.wikipedia.org/wiki/Bengal

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Bangladesh: Physical Environment

•Major natural assets of Bangladesh are its access to the open Ocean, the tropical climate, the abundance of good soils, and the seasonal abundance of rainfall and river flow.

•It is often said that Bangladesh is poor in natural resources, but this is not true.

•By natural resources some refer only mineral and gas resources, which are apparently scarce in the alluvial basin, but even that superficial view has began to change with further exploration.

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Bangladesh: Physical Environment

As tropical climate is another asset, which enables crops to be grown throughout the year, unlike countries in high latitudes.

In Bangladesh, temperatures are seldom below 7 degree Centigrade, considered critical tropical plant growth.

Sunshine is abundant, even during the rainy season (“the Monsoons”), enables high-yielding crops to be grown.

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Climate of Bangladesh Sub-divisions of Climate Climatic change Climatic zones Impact of climate

Climate of Bangladesh

The Ganges Padma River SystemThe Brahamaputra & jamuna River SystemThe Surma-Meghna River SystemImpact of river systems

River Systems of Bangladesh

FloodTypes of floodFactors of floodImpact of floodHistorical overviewFlood mitigation Practice in BangladeshPossible flood mitigation strategies


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Climate of Bangladesh

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Climate

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Climate of Bangladesh:

� In Bangladesh we see tropical climate. But has a great impact of monsoon climate. For this reason three seasons are observed in Bangladesh. These are ;

� Summer, Winter, and Rainy season.

Climate the average condition of the atmosphere near the earth surface over a long period of time, taking into account temperature, precipitation, humidity, wind, cloud, barometric pressure etc.

Climate:

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Summer Season

� Time: From March to May.

� Temperature: Highest temperature is about 34ºc and lowest is 21ºc.

� Wind Flow: In summer moist and dry monsoon wind is flow from south west and other cold and dry monsoon wind is flow from north west.

� Rainfall: For these two winds Nor’wester is happen in Summer. Average rainfall is 51cm..

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Winter Season

� Time: From November to February.

� Temperature: Highest and lowest Temperature: About 29ºand 11ºc.

� Wind flow: Cold Northeast monsoon wind is blow in this season.

� It’s lowest humidity is 36%

� Rainfall: It is about 5 to 15cm.

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Rainy Season

� Time: From June to October.

� Temperature: Average Temperature is 27ºc.

� Wind blow: Southwest monsoon wind is blow.

� Rainfall: Average highest and lowest rainfall is 340cm and 119cm

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Characteristics of climate in Bangladesh :

Main characteristic of climate in Bangladesh is warm moist

Summer and cold temperate Winter.

When season changes then the speed of wind is also change.

June-July is the warmest and December-January is coldest

month.

.

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Climatic MapClimatic MapOfOfBangladeshBangladesh

( Temperature & Rainfall )

Source: Banglapedia

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Sub-divisions of Climate :Sub-divisions of Climate :

We all ready know that Climate is a average condition of some elements such as follows ~

Atmospheric pressure & winds

Temperature

Humidity

Clouds

Rainfall

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Atmospheric pressure & winds :Atmospheric pressure & winds :

These are characterized by seasonal reversals betweenSummer & Winter in Bangladesh.In winter, a centre of high pressure lies over the North-Western part of India.In summer a centre of low pressure develops over theEast-Central part of India.

Temperature :Temperature :

January is the coldest month, average temperatureis about 17°C in the north-western part & north-easternparts to 20°C-21°C.April is the hottest month, average temperature is about 27°C in the northeast to 30°C in the extreme west centralparts.

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It has an important role upon climate. The condition of

humidity in Bangladesh given bellow ⇒⇒

Humid condition

Period Area %

Least humidity March & April Western part +57%

January to March Eastern part +59%

Relative humidity June to September Everywhere 80%

Average relative humidity

Whole year Everywhere 70.5% - 78.1%

Humidity :Humidity :

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Clouds:Clouds:

In Bangladesh, the cloud cover has two opposing seasonalpatterns, coinciding with the winter monsoon & the summermonsoon.

Cloud`s covertness

Period Area %Winter monsoon

Almost everywhere

About 10%

Pre-monsoon Almost everywhere

30-40%

Summer monsoon

north-western 75%

Southern & Eastern

90%

Cloud covertness in Bangladesh given bellowCloud covertness in Bangladesh given bellow ~

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Rainfall:Rainfall:

The single most dominant element of the climate of Bangladesh,because its location in the Tropical monsoon Tropical monsoon regionregion.

Source: Banglapedia

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Source:http://www.fas.org/irp/imint/docs/rst/Sect14/India_TRMM2004194.jpg

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Figure :-Figure :-Humid condition Humid condition of Bangladesh.of Bangladesh.

Figure :-Figure :-Cloud covertness.Cloud covertness.

0102030405060708090

Western part Eastern part Everywhere Everywhere

(March & April) (January to March) (June to September) (Whole year)

Least humidity Relative humidity Average relativehumidity

Humidity (%)

010

2030

4050

6070

8090

100

Almosteverywhere

Almosteverywhere

North-western Southern &Eastern

Winter monsoon Pre-monsoon Summer monsoon

Cloud covertness (%)

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Climatic stations :Climatic stations :

Bangladesh Meteorological Department is responsiblefor observation, recording & archiving of climatic dataof various stations in the Country. Like – Cox's Bazar,Bhola, Jessore, Dhaka, Dinajpur,etc.

Weather report :Weather report :

Bangladesh Meteorological Department prepares the weather reports of the country, which broadcast byMass-communication.

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http://www.lged.org/sre/windmap.jpgwww.fao.org/ag/AGL/swlwpnr/reports/y_sa/z_

bd/bdmp131.htm

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Climatic change :Climatic change :

Besides Deforestation has an important role upon climaticchange. Higher rate of population growth is responsiblefor Deforestation.

Any climatic change in Bangladesh will, of course, be a part of Worldwide climatic changes.

The temperature has been increasing since the beginning of the 20th century. It is called GLOBAL WARMING and due to the burning of fossil fuel.

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Climatic Zones:Climatic Zones:Bangladesh is located in the tropical MONSOON region.On the basis of entire climatic condition Bangladesh can be divided into seven distinct climatic zones, as follows -

Name Area Temp(°C) RainfallSouth-eastern Costal belt &

chittagong13°C-32°C +2540 mm

North-eastern East & south sylhet 10°C-32°C 3000 mm

Upper northern Northern part 10°C-32°C +2000 mm

North-western Kushtia,Bogra,Rangpur

10°C-32°C 1750 mm

Western Greater Rajshahi 7°C-35°C 1500 mm

South-eastern Jessore,Rajbari,etc. 12°C-32°C +1500 mm

South-central Most of the central part

15°C-31°C +1900 mm

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0

5

10

15

20

25

30

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No

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Up

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We

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Temp(°C) Rainfall(mm)

Figure :- Temperature & Rainfall according to the Climatic Sub-region.

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Climatic sub-region areShown in the map ~

A- South-eastern zoneB- North-eastern zone

C- Upper northern zone

D- North-western zone

E- Western zone

F- South-eastern zone

G- South-central zone

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Impact of Climate

� Impact on Agriculture

� Impact on Industries

� Impact on Forest resources

� Impact on fisheries

� Impact on trade and commerce

� Impact on transportation

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Above figures show us Cyclone & Flood affected area of Bangladesh,Above figures show us Cyclone & Flood affected area of Bangladesh,which is the extreme view of weather as well as climate.which is the extreme view of weather as well as climate.

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RIVER SYSTEMS

OF

BANGLADESH

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Bangladesh is a land of river. River is an important feature of physiographic . The pride of Bangladesh is its rivers with one of the largest networks in the world with a total number of about 700 rivers including tributaries, which have a total length of about 24,140 km.

RIVERRIVER: A volume of water which flows in a channel : A volume of water which flows in a channel from high ground to low ground and ultimately to a from high ground to low ground and ultimately to a lake or the sea.lake or the sea.

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River / Length (km) : River / Length (km) : Arial Khan160 Bangshi 238 Betna-Arial Khan160 Bangshi 238 Betna-Kholpotua 191Bhadra 193 Bhairab Kholpotua 191Bhadra 193 Bhairab 250 Bhogai-Kangsa 225 Brahmaputra-250 Bhogai-Kangsa 225 Brahmaputra-Jamuna (Jamuna 207) 276 Buriganga Jamuna (Jamuna 207) 276 Buriganga 27Chitra 170 Dakatia 207 Dhaleshwari 27Chitra 170 Dakatia 207 Dhaleshwari 160 Dhanu-Baulai-Ghorautra 235 160 Dhanu-Baulai-Ghorautra 235 Donai-Charalkata-Jamuneshwari-Donai-Charalkata-Jamuneshwari-Karatoya 450 Ganges-Padma (Ganges Karatoya 450 Ganges-Padma (Ganges 258, Padma 120) 378 Gorai-Madhumati-258, Padma 120) 378 Gorai-Madhumati-Baleshwar 371 Ghaghat 236 Karatoya-Baleshwar 371 Ghaghat 236 Karatoya-Atrai-Gur-Gumani-Hurasagar 597 Atrai-Gur-Gumani-Hurasagar 597 Karnafuli 180 Kobadak 260 Kumar Karnafuli 180 Kobadak 260 Kumar 162 Kushiyara 228 Little Feni-Dakatia 162 Kushiyara 228 Little Feni-Dakatia 195 Lower Meghna 160 Matamuhuri 195 Lower Meghna 160 Matamuhuri 287 Mathabhanga 156 Nabaganga 230 287 Mathabhanga 156 Nabaganga 230 Old Brahmaputra 276 Punarbhaba 160 Old Brahmaputra 276 Punarbhaba 160 Rupsa-Pasur 141Sangu 173 Surma-Rupsa-Pasur 141Sangu 173 Surma-Meghna 670 Tista 115 Meghna 670 Tista 115 SourceSource BBS 1999 BBS 1999..

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RIVER SYSTEM OF BANGLADESH

The river system of Bangladesh is divided in three types:The river system of Bangladesh is divided in three types:

1. GANGES PADMA RIVER SYSTEM

2. BRAHMAPUTRA & JAMUNA RIVER SYSTEMN

3 The SURMA-MEGHNA RIVER SYSTEMN

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GANGES PADMA RIVER SYSTEM

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GANGES/PADMA RIVER

SYSTEM:

This river being originated Himalayas and are mainly snow-fed.

The mighty river Ganges enters Bangladesh through its north western side and changes its name to Padma.

The Kumar, Mathabhanga, Bhairab,Garai, Madhumati,

Arialkhan are the chief branches of the Padma & the Mahananda is the main tributary .

The Punarbhaba,pagla,kolik,Tangan are the tributaries of Padma

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Greatest

Delta in

the

Ganga Padma basin

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The Padma Ganges & its distribution system.

RIVER MILES KM

Total length of 700 river . 13770 22155

Padma a. West region b. At pabna c. At Nawabgang d. At taltala confluence

554 892

43 70

57 92

21 33

199 320

The Padma Ganges 190 305

Mathabhanga 80 128

Ichamati 56 90

Bhaira 99 590

Kumar 275 443

kubadak 174 280

Chidra 117 188

Garai, Madhumati 195 314

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BRAHMAPUTRA & JAMUNA RIVER SYSTEM

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BRAHMAPUTRA & JAMUNA RIVER SYSTEM :

The Jamuna-Brahmaputra is 292 kilometers long and extends from northern Bangladesh to its confluence with the Padma. Originating as the Yarlung Zangbo Jiang in China's Xizang Autonomous Region (Tibet) and flowing through India's state of Arunachal Pradesh, where it becomes known as the Brahmaputra ("Son of Brahma"), it receives waters from five major tributaries that total some 740 kilometers in length. At the point where the Brahmaputra meets the Tista River in Bangladesh, it becomes known as the Jamuna. The Jamuna is notorious for its shifting subchannels and for the formation of fertile silt islands (chars). No permanent settlements can exist along its banks.

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Sat image on BRAHMAPUTRA & JAMUNA RIVER SYSTEM

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The Jamuna & Brahmaputra River system

RIVER MILES KM

Total length of 700 rivers 13770 22155

Teesta 174 280

Old Brahmatutra 217 350

Dhaleswari 139 224

Buriganga 17 27

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THE SURMA-MEGHNA RIVER SYSTEM:

The third network is the Surma-Meghna system, which courses from the northeastern border with India to Chandpur, where it joins the Padma. The Surma-Meghna, at 669 kilometers by itself the longest formed by the union of six lesser rivers river in Bangladesh, is. Below the city of Kalipur it is known as the Meghna. When the Padma and Meghna join together, they form the fourth river system--the Padma-Meghna--which flows 145 kilometers to the Bay of Bengal.

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The Meghna& Surma distribution system.

RIVER MILES

KM

Total length of 700 rivers 13770 22155

Surma-Meghna (Border to chadpur)

375 574

Meghna from Chandpur to Bay of Bengal

99 160

Surma 217 350

kushiyara 68 110

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NAME OF THE RIVER MILES AREA COVER

Surma Meghna 416 sylhet(180),comilla(146),barisal(90)

Karatoya,atrai,hursagar 371 Dinajpur(161)rajshahi(160)pabna(50)

Donai,karatoya 280 Rangpur(120)bogra(98)pabna(62)

Ganges,padma 233 Rajshahi(90)pabna(60)dhaka(60)

Garai,Modhumati,Baleswar 231 Kushtia(36)faridpur(70),khulna(104)

Old Brahmaputra 172 Mymenshingh(172)

Brahmaputra & Jumuna 172 Rangpur (75)Pabna(75)

Bangshi 148 Mymenshingh (123 Dhaka(25)

Ghagat 247 Rangpur(247)

Dhanu,Boulai 146 Sylhet (68) Mymenshingh(78)

Nobaganga 144 Kushtia (16) Jessore (128)

Kushiyara 142 Sylhet (142)

Bhogal-kangsa 140 Mymenshingh(140)

RIVER & ITS COVER AREA

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Impact of River Systems

� Impact on Economy

� Impact on Agriculture

� Impact on Flood

� Impact on Environment

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Flood

At the present time 130 million people of Bangladesh are facing a

series of environmental problems.

Flooding is one water- related environmental problem that is directly

related to human activities.

The magnitude and intensity of flooding are very much dependent

on land-use practices in the watershed of each rivers or streams.

Finding solutions to the flooding problem is imperative.

It is important to understand the processes that influence flooding in

Bangladesh, before any solution to the flooding problem is

prescribed.

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Flood relatively high flow of water that overtops the natural or artificial banks in any of the reaches of a stream.

Unusual or above normal surface-water flow that inundates otherwise high ground is called a flood.

Riverine floods occur when the amount of water flowing in a drainage basin or watershed (the area that collects and directs the surface water into the streams that drain it) exceeds the carrying capacity of rivers which drain the area.

DEFINITION OF FLOOD

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TYPES OF FLOOD

Monsoon flood-caused by major rivers usually in the monsoon (during June-September).

Flash flood-caused by overflowing of hilly rivers of eastern and northern Bangladesh (in April-May and September-November).

Tidal flood-caused by storm surges.

Local flood.-Rain floods caused by drainage congestion and heavy rains.

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Flo

od T

ypes

Map

Source:

www.apfm.info/pdf/case_studies/bangladesh.pdf

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Short-term Causes

� Monsoon downpour

� Synchronization of Flood Peaks

� Rainfall of the up stream

CAUSES OF FLOOD

Short term causes

Long term causes

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Source: Banglapedia

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Long-term Causes � Topographical Characteristics� Subsidence and Compaction of Sediments � Riverbed Aggradations � Deforestation in the Upstream Region� Damming of Rivers � Soil Erosion due to Tilling � Excessive Development/Unplanned development � Seismic (Earthquake) and Neotectonic Activities � Greenhouse Effect/snow malting in Himalayans� Local Relative Sea Level Rise

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•About 50% of the country is within 6-7 m of MSL.

Figure 1: Topography of Bangladesh

Source: National Plan for Disaster Management2007-2015Ministry of Food and Disaster ManagementApril 2007

64Source:http://www.geog.ucsb.edu/~jeff/115a/remote_sensing/radar/bang_sealevel1.jpg

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HISTORICAL OVERVIEW

Source:http://www.sdnbd.org/sdi/issues/floods_drainage/article/flooded_area_1954_to_2005.htm

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Source: BanglapediaSource:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

67Source:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

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Source: BanglapediaSource:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

77Source: Banglapedia Source:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

81Source:http://phys4.harvard.edu/~wilson/arsenic

/countries/bangladesh/bangladesh_map4.gifSource:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

83Source:http://www.searo.who.int/Image/map_ban2.gif

Source:Roll-020300,(2003-04)Mapping of the Flood Affected Area of Bangladesh,1955-2004.

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Summarized Table of floods in Bangladesh from 1904 to 2004

# of

Events

Killed Injured Homeless Affected TotalAffected

DamageUS (000's)

Flood 62 49,680 102,020 60,853,724 278,043,273 338,999,017 9,165,100

ave. per event 801 1,646 981,512 4,484,569 5,467,726 147,824

Created on: Aug-1-2004. - Data version: v07.04 Source: "EM-DAT: The OFDA/CRED International Disaster Database,

www.em-dat.net - Université catholique de Louvain - Brussels - Belgium"

Source:http://www.sdnbd.org/sdi/issues/floods_drainage/2004/data/index.htm

Historical effect due to flood

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Top 10 Natural Disasters in Bangladesh

Disaster Date Killed

Famine 1943 1,900,000

Epidemic 1918 393,000

Wind Storm 12-Nov-1970 300,000

Wind Storm 30-Apr-1991 138,866

Wind Storm Oct-1942 61,000

Wind Storm 11-May-1965 36,000

Flood Jul-1974 28,700

Wind Storm Jun-1965 12,047



(sorted by numbers of people killed )


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Disaster Date Affected

Flood 22-Jul-1987 73,000,000

Flood Aug-1988 73,000,000

Flood Jul-1974 38,000,000

Flood May-1984 30,000,000

Drought 5-Jul-1983 20,000,000

Flood Jul-1968 15,889,616

Wind Storm 11-May-1965 15,600,000

Wind Storm 30-Apr-1991 15,438,849

Flood 8-Jul-1998 15,000,050

Flood 15-Jun-1995 12,656,006

Top 10 Natural Disasters in Bangladesh(affected sorted by numbers of people )


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Flood Impact

� Physical

� Social

� Cultural

� Economical

� Political

� Agricultural

� Infrastructural

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Flood Mitigation Practices in Bangladesh

� Structural Mitigation

Flood Action plan

� Non structural Mitigation

Flood warning System

Others

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Flood Action PlanFlood Action Plan (FAPFAP) :

FAP is an initiative to study the causes & nature of FAP is an initiative to study the causes & nature of floodfloodin Bangladesh & to prepare guidelines for controlling in Bangladesh & to prepare guidelines for controlling It.It.

It included 29 different components of which 11 wereIt included 29 different components of which 11 wereregional.regional.

It has 11 guiding principles.It has 11 guiding principles.

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Flood Forecasting� Flood warning has been in a state

of continuous development since 1972.

Source: National Plan for Disaster Management2007-2015Ministry of Food and Disaster ManagementApril 2007

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Possible Flood management and mitigation strategies

� Structural solutions and� Non structural solutions.

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Structural Solutions

� Structural solutions call for the engineering of structures such as embankments along rivers, dams, drains, reservoirs, and other structures designed to control the natural flow of rivers.

Dredging and Re-excavation of Rivers

Dams

Others

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Non structural Solutions

Preventing Land DegradationFlood Preparedness Interbasinal Cooperation

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Conclusions

� The climate, river systems and the flood, all are closely related. The Climate of Bangladesh is closely related with the monsoon which is also closely related with the flood and river systems.

� The climate of Bangladesh is changing. The result is observed in the flood by the river system.

� The life of Bangladeshi people are closely related with the climate, rivers and floods.

l 02-bangladesh-geographical & environmental settings

Education