Haor Flood Protection: Fact vs Fiction

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This year few area of the North Eastern area, known as Haor, threaten by the early flash flood damaging Boro crops just before harvest. Important to note, this Boro paddy is the only crop in a year that can is produced in the Haor Area. The low lying area of 7 or 9 districts of the north eastern part of the country, the Haor Flood Management system based in the low height submersible embankment, the type of embankment designed to protect the per-monsoon flood and remains under water during monsoon with higher level of water.

Is it possible to protect the per-monsoon flash food for protection of Boro Paddy in all years? Actually the farmer and the people expecting, that the low height submersible embankment based flood protection system always protected the Boro Paddy from flash flood. Let us try to understand the fact of this expectation.

The land level of the Haor area ranging from one to three meter above the mean sea level, much lower than the Dhaka city, the Bhariab Bazar and Narsingdi. Fact is that, the drainage route of the entire Haor region is through Bhairab Bazar – Narsingdi – Chandpur by the Maghna River. Northern side boundary of the Haors is Meghalaya Hills, where the highest annual rain fall region of the world Cherrapunji about 20 km away from the Bangladesh Boarder of Sunamgonj. At Cherrapunji average annual rainfall is about 14000mm. Haor region inflow accumulated from the rains of Meghalaya Hills in the north, Barak Basin in the east. There are 21 rivers or streams enters Bangladesh from India ranging from Sherpur, Netrokona, Sunamgonj, Sylhet, Moulvibazar, Habigoj and Brahmmanbaria districts. In addition of 21 rivers or streams overland flow also feeding low-lying Haor area. Height of the Meghalaya Hills ranging from 325 to 450 meter above the mean sea level. The clouds coming from the Bay of Bangal and Indian Ocen can not cross or over top the Cherapunji, the Meghalaya hills. All rain falls on to the Meghalaya hills in the north or Barak Basin in the eastern side. The drange rout is, mentioned earlier is only one the Meghna river, under the Megna rain and road bridge, make the Haor drainage very slow.

The earthen submersible embankment not able to sustain with water level difference of 20 to 24 feet and failed
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Height submersible embankment is 6.5 meter in Sunamgonj and Netrokona districts, specifically designed to protect the per-monsoon flood of average or below average year rainfall. Reality is that every year is not the year with rainfall of average year or below average year or dry year. Submersible embankment with 6.5 meter high is not supposed to protect the flood generates with rainfall of above average year coming from 325 m to 450 m high hills. This the fact of the Haor region. Years with rainfall Text Box: Effort to repair the submersible embankmentabove average year or dry year, the floods overtopping the submersible embankment causing the damage of the Boro paddy. Such crop damage happened in 2004, 2010 and again in 2017. In those years, heavy to very heavy rainfall in the Cherrapunji, the Meghalya Hills and Barak basin in per-monsoon, March, April period generates huge discharge, immediately flows in the Haor area and flooded all the cropped area just before the harvest. In those years crop damage was about 80%, conceding huge loss by the farmers, put pressure to the National and country’s food security.

This the main reign of Boro Paddy damage in 5 or 7 or 10 years interval with ore-monsoon flash flood.

Effort to repair the submersible embankment
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EIP is the largest development effort made by the Netherlands Government, contributing huge improvement of paddy production from the Horas. Recently the Japan Govt through JICA initiated for the improvement of 29 Horas in the North Eastern region of Bangladesh.

Its major development initiated is after the big flood of 1974 and crop loss, when the Dutch government came forward at the request of the Father of the Nation Bangabandhu Sheikh Mujibur Rahman. In early 1975, the Administrative and Financial Agreement was signed with the Dutch government. From 1975 to 1998, the Haor undertook a many development work under the Early Implementation Project-EIP with the help of the Dutch government along with the Systems Rehabilitation Project-SRP with the help of EU and Dutch in the period 1992-97. Since then there has been no major investment or development done in the HAor area. EIP is the largest development effort made by the Netherland Government, contributing huge improvement of paddy production from the Haors. Recently the Japan Govt, through JICA, initiated for improvement and development of 29 nos of Haors in the North Eastern region of Bangladesh.

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Another challenge is to make permanent submersible embankment and the cross dams in the Haor, because after the monsoon (October-November) Cross-Dams an Embankment have to be cut in more than one place to drain the water from each Haor, otherwise there will be high water level in the land at the time of transplanting of Paddy. When water comes out or is drained in that way, huge scour depths are made with the velocity of outgoing water for 2/3 months. Due to natural causes, drainage is delayed, so transplanting of paddy is delayed, again with early onset of rains in this area, even in February-March-April, hence the two-way time limit is another reality.

It would be wrong to evaluate per-seasonal flood management or flood prevention systems based on sub-immersible embankments of Haor on a yearly basis. Considering average rainfall, heavy rainfall (more than 89 mm per day) or 5 or 7/10 year based time scale evaluation is justified. As far as I remember, after 2010, heavy rains and early downpours in Haor in 2017 caused severe damage to crops (about 80%), then this time, in 2022.

Farmers try to harvest whatever they can

Local Innovative Techniques This local and relevant strategy of crop protection has evolved over many years. The big limitation of this is that all year 100% flood protection is not possible. But why this strategy of protecting the crops of Haor with this low height, short height dam or submersible embankment. The advantage of this is the system of harvesting crops by preventing early floods caused by average rainfall or below average (up to 10th of April or May). As was happening every year after 2017 (2018, 2019, 2020, and 2021 four years), farmers able to harves the Boro Paddy fully without any flood damage. But this year nature or the superior, the Almighty Allah, was not so kind. Another fact is that without this low-altitude, low-altitude embankment or submersible embankment, 25% or 35% of the Haor area will not be able to cultivate any paddy at any time of the year and will be submerged due to rain or water coming down from the hills. People who work in the Haor area topography, land level and rainfall know this.

However, there could be few measures that might reduce the risk of flooding or particularly early flash flood in the future. Such as river re-excavation or dredging. However, I would like to say that by doing this, the risk of flood or early flash flood in Haor can be reduced, but not possible to remove the risk, it is impossible to save 100% every year. For Haor area Flood Risk may be or could be REDUCED, could not be REMOVED or ELIMINATED.

Md. Amirul Hossain
Additional Chief Engineer
PRL, BWDB.

e-mail : amirulbwdb@yahoo.com

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