by Md. Sirajul Islam
Bangladesh attracts little attention from the international news media except for its occasional catastrophic flood incidents. This year’s flood was one such case, reported by news organizations all around the world. Being crisscrossed by hundreds of rivers and having a flat deltaic or flood plain, Bangladesh has a long history of devastating floods. Nonetheless, the country has attracted a large population due to its fertile land and abundance of water for such beneficial purposes as irrigation, fishing, transportation, and domestic use.
Approximately six percent of the countryâ€TMs total landmass is covered by permanent water bodies such as rivers, lakes, and estuaries (Figure 1).
Eighty percent of the country is a floodplain that is submerged for two to five months each year during the annual monsoon. It is these floodwaters that bring the large amounts of silt that make the land among the most fertile in the world. Presently, Bangladesh is the world’s most densely populated country (Table 1 [1]). History shows that this was once one of the most prosperous regions in the world, with huge agricultural production and a comfortable climate, ranging from 20 to 30°C throughout the year.
In fact, most ancient civilizations were built along the banks of great rivers, such as the Egyptian civilization along the banks of the Nile, the Persian civilization along the banks of the Tigris and the Euphrates, and the Indus civilization along the banks of the Indus. This might also explain the growth of the Bengali civilization along two mighty rivers, the Ganges and the Brahmaputra (Figure 2 [2]). The question arises, however, of why, while our ancestors migrated there and found it to be a suitable place to live, Bangladesh is becoming unlivable nowadays, frequently suffering from devastating floods. How did our ancestors manage the flood problem?
A group of conservative people are confident that the flood problem can be blamed on unplanned settlements and modern efforts at flood control policies, such as the use of embankments. According to these individuals, these embankments, called “cordons,†simply hinder free flow of water along the flood plain and aggravate flood damage. We should not try to separate ourselves from the rivers, however, but instead compromise. The permanent solution to flooding lies in adopting the time-tested “dig, elevate, and dwell†formula for living in a delta or flood plain that was adopted by our ancestors. They dug ponds, lakes, and canals and used the earth obtained from these to elevate the ground level of their dwellings. They thus allowed the rivers to reach their doorsteps without drowning themselves. [3] Supporters of this group officially defined this approach as the “open approach†- that is, let the delta be open to allow the mighty rivers to breathe and thereby reduce the elevation of the flood level.
According to these proponents, other options like “cordon approaches†are not only technically unfeasible or environmentally unsound but also can create social problems. People dwelling inside the protected areas should not be treated differently from those living in the rest of the country. Again, because of those protected by cordoned or embanked areas, the water level at those unprotected areas rises according to continuity equations. This is sure to generate conflicts between areas that are protected from floods and areas that are not. In many cases, it happens that those unprotected people cut the embankment, sometimes even those who are living inside the cordoned areas.
Engineers and hydrologists, mostly from the public sector, however, disagree with the so-called “open approach,†saying that the modern age is quite different from that of our ancestors. Hydrological science has advanced significantly, such that instead of compromising, we should try to control floods. Using today’s modern hydrological models, it is also possible to assess the probable impact of a flood control measure like drainage congestion or rise in water level in the surrounding areas. [4] Again, the situation in the delta has changed significantly, so the solution is not as easy as simply allowing a free flow, as proposed in the open approach. Over time, the population density has increased, agricultural production has diversified, and new cities and industrial areas of economic importance have immerged. We should at least save places of economic importance through the “cordon approach,†for the interest of the nation as a whole.
After every large flood (Figure 3 [5]), like the one that occured in 2004, debate occurs on a permanent solution to flooding in Bangladesh. For example, the flood in 1954 led to the Cruig Commission and the projects that it recommended. Similarly, the flood in 1988 led to the most controversial Flood Action Plan (FAP). Most of the large flood control structures like the Dhaka-Narayanganj-Demra (DND) project and the Brahmaputra Right Hand Embankment were built following the report of the Cruig Commission. A protective embankment surrounding Dhaka was created after the flood of 1988. The approaches were mostly structural, using the “cordon approach†either to protect an area of agricultural or administrative importance or to seal the river banks. The FAP was the most seriously criticized initiative in this context, due to its high dependence on structural measures. Many social scientists also say that flood control projects like the FAP are prepared mostly by engineers, leaving less emphasis on the participation of people from all walks of life.
Whether these cordoned flood control projects have failed, however, is a matter of continual debate. According to government engineers, the projects are not complete failures but could not produce expected results due to a shortage of funding for maintenance and upgrades. Nonetheless, the projects implemented to date contribute significantly to the national economy. Bangladesh’s water management projects have enabled the country to produce 7.66 million tons of additional food grain annually, which is about 33 percent of the country’s total production. Similarly, town protection projects like the DND project and the Greater Dhaka protection embankment effectively saved Dhaka from flooding during this yearâ€TMs unprecedented flood. In 1988, the damage caused by flooding in Dhaka almost constituted the damage bill for all of Bangladesh. The flooding of Dhaka thus paralyzed the entire country.
During this yearâ€TMs flood, however, another problem hit Dhaka: the overflow of sewage that flooded many low-lying parts of the city. The embankment surrounding Dhaka was designed to protect the city from floodwaters outside the city, but the pump stations were not enough to push out the floodwaters come from inside the city. Unplanned housing, which has grown more abundant since the embankment was built, also aggravated the situation. Due to safety concerns inside the embankment, people are now even building their houses below flood level or in low-lying areas by filling water-retaining bodies such as lakes, ponds, and canals. Dhaka has experienced an unprecedented growth rate in recent years and has already crossed the threshold of 10 million people to be named a mega-city. Land is precious in Dhaka, and most of the natural canals that historically flowed through the city have been either filled by illegal land grabbers or have narrowed and become clogged. All these factors have exacerbated the internal flooding conditions of the city, making life unbearable. Proponents of the “open approach†are quite critical of the supposed success of the Dhaka embankment, pointing to what they see as its many drawbacks.
It is important to mention here that Bangladesh’s geographical location makes it forever prone to flooding. Bangladesh is situated at the downstream end of the two mighty rivers, the Ganges and the Brahmaputra. Along with another large river, the Meghna, this Ganges—Brahmaputra—Meghna (G-B-M) basin covers an area of approximately 1.75 million square kilometers, constituting the second largest flow-producing catchment in the world, after the Amazon, with an annual discharge of approximately 1.35 trillion cubic meters (Figure 4 [6].) When the peaks of these three rivers synchronize, flooding is virtually unavoidable. Unfortunately, around 84 percent of the total river discharges in Bangladesh are generated outside the country, so it has little control over the situation. The regulation of water at the upstream sections of the rivers, in India, plays an important role, as 54 out of 56 transboundary rivers entering Bangladesh first run through India. Sedimentation by silt (about 600 million tons annually) in the riverbeds significantly reduces the total conveyance capacity of the rivers. Most of the sediment comes from the Himalayan region upstream and starts to settle just after entering into the flat plain of Bangladesh. Deforestation along the Himalayas plays an important role here. Clearly, the flood problem in Bangladesh cannot be solved by this country alone, but requires cooperation with its neighbors.
Bangladesh’s high population density and its growing communication networks also obstruct the water drainage routes, increasing flood levels. The country’s population is still growing quickly, and people in search of new land often fill water bodies indiscriminately. Another important factor is the impact of long-term climate change and the associated rise in sea level. As a flat, low-lying country, Bangladesh is one of countries in most serious danger of this effect. A one-meter rise in sea level, for instance, could cause around 17 percent of the country to be inundated. In addition, increased snowmelt in the Himalayan region in a warmer climate will further aggravate the flooding problem in downstream countries like Bangladesh.
Clearly, it is impossible to permananently control flooding in such a complex situation either by use of the open or cordon approaches alone. The truly sustainable solution should be something between these two extremes. Cooperation with neighbouring countries would be the best option, if this were possible. Unfortunately, little progress has been achieved to date on this issue. The solution also requires comprehensive research on the cause and effect relationship of flooding in Bangladesh that is more substantive than the typical studies proposed by many consulting firms. Unfortunately, such serious research is rarely performed on this issue, specifically in Bangladesh. To date, most of the flood-control projects that have been implemented in Bangladesh came out of the Cruig Commission report dated from half a century ago. The topography, settlement nature, and socio-economic condition of the country has changed extensively within this time. Neither the Cruig Commission report nor the Flood Action Plan was produced by local experts, but instead by foreign professionals. Little communication took place with local people in the preparation of these two documents. This leaves a wide range of possible flaws in the proposals that could not be detected through a purely theoretical understanding of the complex delta, without any practical experience with its intricacies. Of course, foreign experts are most welcome to participate, but there is a need for extensive studies and experience in the field. There is ample scope in Bangladesh to do substantial research on the subjects of flood theory and control measures.
Historically, the rivers in Bangladesh hosted the country’s large population by providing food, nutrition, and a means of transport. Today, Bangladeshis still think of these rivers not as hostile, but as congenial and conducive of a good way of life in the region. Continued devastation by floods, however, has made the people begin to wonder how long they can remain in harmony with these great rivers. There is an urgent need to find a sustainable solution to this problem. As a developing country with a myriad socio-economic difficulties and meager resources, however, how far Bangladesh can progress toward this goal is a question to seriously ponder.
- Md. Sirajul Islam, Oki & Kanae Laboratory, Institute of Industrial Science, University of Tokyo, Tokyo, Japan; originally from Bangladesh
Footnotes
[1] Geo Hive, “Global Statistics,†http://www.geohive.com
[2] Maps.com, http://www.maps.com
[3] Nazrul Islam, “A Permanent Solution to Floods,†The Daily Star, Dhaka, Bangladesh, 10 August 2004, http://www.thedailystar.net/2004/08/10/d408101501100.htm
[4] Engr. Md. Amirul Hossain, “A Permanent Solution to Floods: Point to Ponder,†The Daily Star, Dhaka, Bangladesh, 13 August 2004, http://www.thedailystar.net/2004/08/13/d40813020530.htm
[5] Bangladesh Water Development Board, http://www.bwdb-bd.org
[6] Institute of Water Modeling, Bangladesh, http://www.iwmbd.org
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