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Where India meets South East Asia: Bangladesh

article: Where India meets South East Asia: Bangladesh

 

 

Where India meets South East Asia, the history and flow of two of the world's greatest religious cultures mingle in the waters of two of its largest rivers. This is a landscape beyond mere superlatives. The waters created in the Himalayas flow out to east and west as the Ganges and Brahmaputra Rivers. The rivers meet form the Meghna, which is second only to the Amazon, and then course south in hundreds of distributaries to form the largest delta on the planet.

This is the landscape of Bangladesh. The 140 million people share culture with Bengali Indians, Muslims and Buddhists, and to a lesser extent the hill people of Myanmar. Ninety percent of the land is flood plain, and "the country has the world's highest density of rivers per unit of area," according to a book edited by Philip Gain, "so it is called 'The gift of the rivers.'"
This great delta is in constant change. Over time river channels writhe like Medusa's hairdo, forming and eating away islands and sandbars depending on the amount of run off, the rainfall of monsoon and cyclones, and the Bay of Bengal tides. Not quite like the Odyssean story, the Bangladeshi people must look this Medusa in the face. Their fate is not being turned to stone but just the opposite -- seeing their lives washed away. The great cyclones (Southern Hemisphere hurricanes) of 1970 and 1991 taught many lessons to the government and people. There is more tree planting, and better warning and evacuation systems for big storms. The Philip Gain book, however, says forest cover has declined from 18 percent in 1927 to 6 percent in 2000, including plantations.

The people are very resilient and used to the vagaries of river and weather. Still the population living along rivers on land less than a meter above high tide makes the issue crucial. Retired national meteorologist M.H. Khan Chowdhury, citing the latest reports available, said "On an average, river erosion takes away about [19,000 acres] of land every year, About one million people are directly or indirectly affected by river-bank erosion every year in Bangladesh." Dr. Chowdhury is part of group of retired Bangladesh government meteorologists and geologists, who believes "people are not very much aware of the effect on them of sea level rise" and a warming climate. These effects, although not yet extensively field studied in Bangladesh, include heavier river flows from melting Himalayan glaciers, more rapid shifts in river channels, stronger high water changes during storms, more intense cyclones and rainstorms, and the fact that all of these are coming on top of the inexorable rise in the ocean itself. Tidal influence up the rivers extents to Dhaka, so even when river flow is normal the level of water follows the sea.

This was impressed on me in a boat journey in June 2005, south from Dhaka. For mile after mile the level of rice fields and buildings along the rivers was no more than a meter above high tide. Much shoreline was lower and filled with water during each high tide. Residents of two villages being eroded away told of faster riverbank loss and of being unable to predict the rivers in time to move houses and rescue families. In the tiny village of Char Kalmi on the west shore of Bhola Island, agitated townspeople pointed out into the river where in April 2005 the mosque was destroyed unexpectedly. This is happening not at the height of monsoon when flooding is common, but at the end of the dry season. I learned that in other villages boat landings are in a constant state of being undermined and even turned into islands during high tides. In the main town of Bhola itself the weather office had to be moved from encroaching waters. Some villages have migrated more than 7 km since the 1980s, leapfrogging houses back away from the edge.

World Bank reported in 2001 sea level rising about 3 mm year in the Bay of Bengal. It warned of loss of Bengal tigers in the Sundarbans, worlds largest mangrove forest, and threats to hundreds of bird species. 15 to 20 percent of Bangladesh is within one meter of sea level. This means predicted sea level rise, at a rate that is increasing, will not only affect millions of people -- estimates are 13 to 30 million -- but will also flood out much rice production. The World Bank warned of a decline of rice crop up to 30 percent with predicted sea level rise. This is not a one-time event that sometime in the future will affect so many. It is a constant process of ever higher tides which affects more and more people even in time of lower river flow and good weather.

References include:
Gain, Philip, ed. Bangladesh Environment: Facing the 21st Century (Society for Env and Human Development, Dhaka, 2002.
Notes from meeting with National Oceanographic and Maritime Institute members in Dhaka, June 23, 2005, and an email follow-up from M.H. Khan Chowdhury
Interviews with residents of Bhola Island, 24-26 June 2005.

World Bank and UN Environmental Programme reports, and report on Climate.org "Bangladesh Is Used to Coping, But Rising Seas Pose New Dangers"

Comments

  • Posted by Cliff Lyon on September 7, 2008 7:06 pm

    Why does the sea-level rise at different rates in different places?

  • Posted by Lucy Kerr on September 7, 2008 7:08 pm

    It is difficult to give a short evaluation of the environmental status of the Indian Ocean as it spans a very large area. However, many of its coastal regions particularly coastlines close to larger cities and big industrial areas experience environmental degradation due to pollution and human activities. Many remote coastal areas and marine areas under marine protection contain healthy or less disturbed marine ecosystems.

  • Posted by grano diorite on December 26, 2008 12:53 pm

    It is a product of tidal gravitaional influences. There is also the issue of geologic subsidence that occurs as unstable rock layers sink into the substarte below, given the appearance of a sea level rise.

    In the case of countries that have huge areas that are anywhere from 10 to 40 ft above sea level, these areas have been subject to massive changes in sea level in the last 10,000 years. During this past Bangledesh and atoll islands seemed quite secure. The volume of ice that has melted in the last 10 so millenia have changed that assumption. Sea level has risen some 3600 inches since the last ice ended and the inter-glacial period of warminghas commenced . Those that could moved to higher ground as there is no way to stop a rising sea. Well, King Canute thought so, but he was wrong.

    Given enough time sea levels equalize but locally can see great diversions. When tides stack in certain way, it can create "hold ups" that defer equallization with sometimes catastrophic consequences. The tide cannot escape as the flow is deferred by another incoming tide. combine this with local weather, winds and storm surge and the appearance that this is happening due to rising sea level can be a mistaken assumption.

    Question I hear from many when I am at the beach: What is the elevation here? The mean of the tidal extremes is at zero ft. Sea level. So in short, sea level is where you find it, and is a product of many factors, the main one being world ambient temperature, that either when cool, allows more preipitation to form upon the land, lowering sea level, when warmer causing more melting, and less ice and snow, leading to the rise in sea level.

    Sea levels have varied wildly in the course of geologic history, and the primary determinant of this situation, has been the output of the Sun, and general cloud cover, water vapor being the most significant greenhouse "gas" in our atmosphere.

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