Presentation on theme: "Bangladesh Under Siege: A geographical examination of a country at the mercy of amplifying natural forces Teacher: Brian McCabe."— Presentation transcript:
Bangladesh Under Siege: A geographical examination of a country at the mercy of amplifying natural forces Teacher: Brian McCabe
Lesson Agenda ► Part one ► Overview of why a study of Bangladesh is important. ► A general look at location, place, and region. ► Bangladesh (regional) climate ► Activity ► Part two ► Natural disadvantages ► Human impact of calamities ► Potential impact from global warming ► Quiz
Objectives Student will be able to: ► Locate Bangladesh on a map and identify its latitudinal position. ► Discuss the importance of studying Bangladesh. ► Analyze and discuss the geography of Bangladesh and the surrounding region. ► Describe what Bangladesh is like. ► Discuss Bangladesh and regional climate ► Identify and analyze natural disadvantages and appreciate their history of natural disasters. ► Understand the potential impact of global warming on Bangladesh.
Why is the study of Bangladesh important? ► In many ways, Bangladesh is a geographical “ground zero” ► Bangladesh is vulnerable from tropical cyclones, storm surges, coastal erosion, and back water effect. ► Their death rate from these natural disasters are among the highest in the world. ► It is nation of 140 million people (3X less just 80 years ago). ► About the size of Arkansas, Bangladesh has about 2,350 people per square mile- making the most population dense nation in the world (Arkansas has only 2.5 million people at about 50 per sqm). ► Over 50 % of Bangladeshis live well below the poverty level, making it one of the poorest nations of Earth. ► About 82% of the population lives in rural areas. Urban growth was limited by poor infrastructure and conditions.
Location, Place, Region ► Pass out map handout ► Keep this map in front of you and we will periodically add to it. ► Locate Bangladesh and shade it in, neatly. ► Locate the Tropic of Cancer at 23.5 degrees north. Draw a line from left to right, where this latitude would be. ► Locate India and Myanmar and label them. ► Locate the Himalayan range and neatly shade in where it would be on a completed map. ► Locate the Bay of Bengal, Indian Ocean, and the Arabian Sea and label them on map.
Location, Place, Region ► Tectonics ► Has Bangladesh always been there? ► Watch movie ► Discussion: ► Was Bangladesh included in this tectonic convergence? Yes ► Being on the Eastern end of this convergence, do you think this played a role in sculpting Bangladesh’s topography? Natural drainage zone ► What mountain range was formed as a result of this continental tectonic convergence? Himalayas ► http://www.asu.edu/co urses/gcu600/gcu672a /4Tectonics/Classroom Resources/ContDriftSe aAge.mov http://www.asu.edu/co urses/gcu600/gcu672a /4Tectonics/Classroom Resources/ContDriftSe aAge.mov ► An animation of the Indian sub-continent crashing into Asia.
Location, Place, Region ► Characterized by two distinctive features: a broad deltaic plain & a small hilly area replete with rivers. ► About 80% of its land-mass is fertile, alluvial lowland delta plain (Plain of Bengal or Lower Gangetic Plain). ► Most of Bangladesh is < 39 feet above sea level. ► 67% of land is arable (define). ► Three mighty rivers combine to form the Sundarbans or “Mouths of the Ganges”: the Ganges, the Brahmaputra, and the Meghna (aka: the GBM river system). These rivers accommodate Himalayan snow melt and monsoonal watershed!
Location, Place, Region ► The Sundarbans are home to the largest mangrove forest in the world. ► The GBM River System deposits mineral rich silt into delta region making it highly fertile. ► Agriculture is Bangladesh’s largest contributor to the economy (jute, rice, and tea). ► The country’s primary religion is Islam, with Hindi, Buddhists, and Christians following in that order. ► The people have a reputation of being wonderfully kind, resourceful, and proud. ► Dhaka, their largest city, has a population of about 12.5 million people.
Location, Place, Region ► The region of the Indian subcontinent is sub-tropical. ► Bangladesh is located on the Tropic of Cancer @23.5 degrees, which means the solar angle is direct on what date? June 21 st or Summer Solstice. ► Because the ITCZ follows the sun, the humid, tropical monsoonal moisture is positioned just south in the Indian Ocean. ► A “High” to “Low” air flow either saturates this region or causes drought.
Climate ► Three seasons are recognized in this region: ► Hot & humid summer from March-June ► Cool & very rainy monsoon from June-October. ► Dry winter from October-March. ► These seasons are driven by several factors: ► Although Bangladesh is located in the Easterly Trade Wind zone under the Hadley cell, the presence of reliable “Highs” and “Lows” drive moisture level and winds. ► During the winter, a Siberian “High” sends cool dry air from Russia. However, in summer, the High becomes a Low and a High forms over the Oceans of Southeast Asia ► Because of high pressure, air flows from High to Low. This means hot, humid air flows towards the Low over Asia. ► This moist air flow then hits the Himalayas, rises, condenses and creates intense rainfall. ► Rainfall can range from 60 to 160 inches a year! ► Pull out map handout and draw arrows indicating monsoonal northeasterly flow. Indicate High and Low.
Climate ► Remember the GBM River System? During monsoon season, the GBM flows at about 140,000 cubic meters per second (only 7,000 during dry season). ► They are also the vehicle for immense Himalayan watershed from melting snow. ► Research has been done linking snow depth with ENSO conditions with GBM flow volume.
What does all this mean? ►1►1►1►140 million people mostly in poverty ►I►I►I►In a country which is 80% below 39 feet above sea-level (most living at or just above SL) ►W►W►W►With the most intense monsoonal rainfall on the planet ►P►P►P►Positioned on the delta of one of the largest high flowing river systems in the world. ►H►H►H►Hmm?
ACTIVITY: 4 groups ► Group 1 and 2 will: ► Take two paper towels and get them wet. ► Then, on a flat surface, push one towards the other, until it collides. ► Push until a large ripple representing the Himalayas forms. ► Then shape the lower towel like India and on the right corner, tear the napkin slightly to look like Bangladesh. ► This activity illustrates the tectonic history of the Indian sub-continent. ► Group 3 and 4 will ► Take tape and mark the floor with three evenly separated pieces. Mark top one “Tropic of Cancer” the middle “Equator” and the lower “Tropic of Capricorn”. ► Then write June 21 st on Cancer September 21 st and March 21 st on Equator and December 21 st of Capricorn. ► Choose a student to take a helium balloon and slowly walk from one tape to another and observe the balloon lagging behind. ► This is an example of how the ITCZ lags behind the sun, causing a late monsoon season.
Human Disadvantages ► Most are poor ► Shortage of land to accommodate people ► Poor food security ► Poor healthcare ► Low literacy (28%) ► Zia International Airport floods, inhibiting aid.
Tropical Cyclones ► About 80 tropical cyclones (TC) of significance form in the world’s oceans, yearly. ► 6.5% form in the Indian Ocean ► Frequency of TC in the Bay of Bengal is 5-6 times that of the Arabian Sea (5.5% of world storms) ► Bangladesh is only hit with.93% of all world tropical storms ► Is Bangladesh safe, then? NO ► If you look at all storms with >5000 deaths, 16 of 35 were in Bangladesh ► 53% of all world deaths related to these storms were in Bangladesh!!! India was second. ► Together, they are hit by only 4.27% of all world storms.
Tropical Cyclones: History ► Bangladesh made this list 16 times, with the highest number of deaths. ► More severe storms caused deaths to rise in 1998, 2001 and as recently as July of 2007 (800 dead so far).
Storm Surges ► Storm surges are generated by the winds and atmospheric pressure changes induced by cyclones. ► Wind moves water and a surge occurs ► Bangladesh has recorded surges up to 10 meters (about 30 feet) not uncommonly ► These surges force sea water up river estuaries, even reversing river flow, on occasion ► Salt water surges up stream causing flooding and killing crops.
Coastal Erosion ► GBM River System has heavy discharge ► Wave action from intense monsoon winds ► High astronomical tides ► Storm surges all contribute to coastal erosion and accretion. ► The mangrove trees are the best defense against these forces, but are shrinking.
Back Water Effect ► This is the retardation of a river outflow by the rise in the level of water at the mouth. ► Storm surges create intense backwater effect. ► This occurs mostly in Bangladesh’s Meghna River estuary, through which about 90% of the river water in the country discharges. ► When this effect occurs, sea water pushes back on out-flowing river water, thereby flooding the interior.
Disease ► In 1988 a study was done to examine patterns of illness in post-flood Bangladesh. ► Of 46,740 patients examined, 34% contracted severe diarrhea, 17.4% contracted respiratory track infections, 47% had watery diarrhea ► Other diseases that spiked concurrently with SLR was Cholera and water-born illness
Human Impact ► The frequency of natural calamities the limited ability to cope with it has led to despair, among many Bangladeshis. ► On top is a dead baby floating in the slums polluted river and below is a man using heroine. ► HIV is on the rise- currently 5% of the population is infected and estimates suggest that by 2030, 8% will be infected. ► Driving the spread of HIV is the increase in prostitution. Though minuscule compared to a neighbor like Thailand or India, many Bangladeshi women have few options available. ► Needle sharing is also a problem: In a study, it was found that of the 5,000 heroine users surveyed, up to 80% share needles. Dhaka has set up safe needle dropping stations.
Global Warming As if Bangladesh needs another problem…
Global Warming ► What are the projected side-effects of global warming? ► Sea-level rise (SLR) ► A 2-4 degree Celsius rise in Sea Surface Temperature (SST)
Global Warming: SST ► Now, if you apply those projected side-effects to Bangladesh, the following outcomes have been proposed by researchers: ► Using high cyclonic frequency zones on the planet (western North Pacific and the Pacific west of Central America and later the eastern Atlantic off the coast of Africa) scientists have identified that SST and cyclonic frequency are likely related. ► Although no direct data supports a link in the Bay of Bengal, if you look at the 115 cyclones from 1877 to 1990 and the 250 cyclonic storms that barely lasted a day, or hit land, and then ask whether that would be the case with a 2-4C rise in SST. Some think a percentage of these storms would have upgraded. ► A greater SST may result in a greater convective instability- leading to an increase in wind speed. The potential result: higher storm surges
Global Warming: SLR ► A SLR (sea level rise) would only intensify the amplitude of these projections. ► Coastal erosion will suffer greater, under global warming conditions. The formula by Bruun (1962) has been used to formulate SLR effects: ► x= ab/ (e+d) ► x: shoreline recession due to SLR a: rise in water from SLR e: elevation of shore ► d: depth of water at a distance and b distance from coastline ► Formula results: coastal erosion due to SLR is about 87 times the SLR ► Example: If SLR is.30 m then the coastal recession will be.18 to.39 m per 1 cm rise of ocean
Hope and the Future ►B►B►B►Bangladeshis are wonderfully optimistic and resourceful. ►E►E►E►Efforts are being made to afforest the mangrove protection zones in the delta. ►F►F►F►Flood-deterrent construction projects are being engineered. ►B►B►B►Bangladesh government is sponsoring and building many cyclone shelters ►Z►Z►Z►Zia International airport is looking to raise runways and build flood deterrent walls, so that aid may get in. ►B►B►B►Better warning systems are being put in place.