How flows become floods

Can dams actually prevent floods in Bangladesh?

Bangladesh Water Development Board (BWDB) has constructed over 15,000 kilometres of embankments and town protection dams all over the country. In the 2015–16 fiscal year, this organisation spent 56.4 percent of its annual budget of BDT 2858.90 crore for the protection of river banks, which included the construction and maintenance of embankments and dams. However, these embankments and dams proved largely ineffective when they were put to the test against this year's flood.

For instance, Kurigram district, through which three of the major rivers and 12 of their tributaries flow, was guarded by a 210-kilometre-long embankment. However, 23 kilometres of this embankment have been completely washed away, and more than 60 percent of it has been severely damaged. In total, 280 kilometres of embankment have been damaged and 35 kilometres have been wiped out by the recent floods in the rest of the northern districts.

Sarwar Hossain, a local inhabitant of the Kundal area of Nilphamari's Syedpur upazila, says, "On August 13, at around 11 am, we heard a loud bang from the Patwaripara area. We headed there and found that the dam was demolished and water was rushing in violently." As the other parts of the dam were about to collapse as well, Sarwar and other locals hastily tried to repair the dam with mud. Army engineers came to assist and reinforced part of the dam by installing sandbags. As they were repairing the Patwaripara section of the dam, another 100-metre-long section of the structure near Basuniapara suddenly collapsed. "As the dam collapsed, we realised that we had no chance of survival. We fled from our houses with whatever we could take. Many of my neighbours lost their livestock and other valuables. I took my wife, my two children, and several thousand takas only," says Sarwar.

According to local inhabitants, the reason behind this otherwise preventable deluge is the lack of maintenance. In fact, Shafiqul Islam, Executive Engineer of BWDB stationed in Kurigram, admitted that 2005 and 2006 were the last times major maintenance work was done on the embankments. On top of that, last year's flood decimated a large part of the embankment, but initiative to restore the damaged section was only taken when the waters of the Brahmaputra and Teesta started to flow well above the danger line. However, it proved too little and too late.

BWDB officials say that due to limited budgets, it usually repairs and reinforces embankments as a response to flood warnings and the demands of locals. "We know better now after this year's flood; we are planning to launch large-scale continuous embankment maintenance projects. We have also gotten permission to recruit 1000 more people. However, we cannot promise there will be no flood next year. Flood control is actually a long-term process," says Mahfuzur Rahman, Director General of BWDB. However, this organisation's efforts to control floods with embankments has proved quite ineffective in many cases due to flawed construction and lack of maintenance. For instance, the Chouhali upazila dam, which cost over BDT 100 crore and took BWDB two years to construct, collapsed two times within six months.

According to Dr M A Matin, Professor of Water Resource Engineering Department of Bangladesh University of Engineering and Technology, says, "Quality of construction and proper maintenance are the two factors responsible for the premature collapse of the embankments." He argues that if the embankment can withstand an annual flood without collapsing, it can be assumed the design of the embankment is perfect. However, the structure needs regular maintenance, which is one of the biggest challenges in Bangladesh. "Manmade activities like building human settlements on the embankment, digging holes in the embankment for personal interests, and taking away concrete blocks and earth from the embankment for construction work are some of the common practices in Bangladesh which make the embankment very weak and vulnerable," explains Dr Matin.

This is why he suggests that the maintenance work of the embankments should include two components: one, repairing the embankments, and two, creating awareness among local people of the significance of this protective structure. In regard to this, Rahman argues that guarding the embankment to protect it from manmade activities is not possible for BWDB due to limited resources. He says, "We cannot guard every section of this massive network. We have a limited budget for maintenance and a workforce of some 6000 men to perform such huge tasks."

Considering these challenges of regular maintenance and resource constraints, experts suggested an alternative method of flood control 28 years ago after the deluge of 1988. In 1989, the Flood Action Plan of Bangladesh proposed a method called compartmentalisation. According to Dr Matin, "Compartmentalisation involves receiving flood waters, then preserving it through enclosed embankments, and finally distributing it through channels in a regulated way to all parts of the country to minimise the impact of flood without negating its contribution to our agriculture." 

This method was proposed keeping in mind the inevitability of floods in Bangladesh due to its geographical location, its people's natural ability to cope with flood, and the beneficial impact of flooding in enhancing the fertility of agricultural lands. However, BWDB claims that implementation of compartmentalisation has recently faced serious challenges as it requires the availability of floodplains for regulated flooding, which has decreased significantly over the last 20 years.

"Human settlements have occupied most of the floodplains. Urban dwellers do not want any type of flooding, whether regulated or natural. Even our farmers do not want flooding nowadays. They can improve the fertility of their lands by using manure and irrigating with river- and ground-water. So, we have now discarded the compartmentalisation method and gone back to building embankments," says Rahman.

During the 1960s, the erstwhile Pakistani government prepared the first Master Plan for water management, which focused mostly on flood control through embankments and drainage improvements. Since then, Bangladesh's flood control system has not seen much progress. Failed initiatives like compartmentalisation and the frequent collapse of embankments have already cost us a vast amount of state resources and human lives. On the other hand, the trend of annual flooding clearly shows the growing intensity of floods in Bangladesh and its devastating impact on the country's agriculture-based economy. Without developing a cost-effective and sustainable flood control system as soon as possible, it will not be possible for Bangladesh to keep its wheels of economic growth in motion for long.

Read the other half of this week's Spotlight: Statistics related to floods and cyclones display a dramatic increase in intensity 

The writer can be contacted at shahnawaz.khan@thedailystar.net.