Reducing the destructive force of cyclones
Cyclones are one of the major natural calamities in our country. These cyclones are caused by formation of low atmospheric pressure over warm waters of the southern parts of Bay of Bengal. After deriving power from high-speed wind and transforming heat and spinning motion from corioli, these cyclones take a northward direction following low-pressure areas into Bangladesh and India. A catastrophic super cyclone like that took place in 1970 can exceed wind speed of 240-kilometer per hour and can trigger tidal bore of 40 feet or more. The cyclone Sidr was 400-500 kilometer wide in size, larger than Bangladesh, and its unstable atmosphere reached the height of 35,000 feet. Its enormous force dislodged underwater debris from 35,000 feet deep ocean and dumped it on the shore. Such severe tropical cyclones can be very destructive to life and property. About 1.5 million people died in November 1970 cyclone, 11,069 in 1985, 1,50,000 in 1991 and 15,000 in 2007. It is estimated that the total damage from Sidr alone is about US$1.6 million. Although 31 years have elapsed since the tragic cyclone of 1970 but the loss of life and property which these cyclones still causes is staggering. One of the reasons is that we have not been able to establish the required defence. Our measures to reduce death and damage so far have been inadequate, piecemeal and halfhearted.
The options to shield the plain lands of our coastal region against so great a force are few and expensive. What are these options? First is to provide an early warning of cyclone and moving the coastal people to cyclone shelters. Thanks to the era of satellites now one can get upto date coverage of the movement of cyclone through global T.V. channels and web sites. While there is still a lot to cover in terms of accurately predicting, where exactly the centre of the cyclone will make landfall and what would be its intensity and impact, the major challenge is to convert this information into a timely evacuation plan. On mid-day of Wednesday 14th November, 2007 many people were evacuated to the cyclone shelters because of the cyclone warning of Bangladesh Meteorological Department. The Storm Centre of BMD in its bulletin forecasted that Cyclone Sidr would make landfall by noon. According to Mr. Farhad Ahmed of Disaster Management Bureau, when the people who took shelter saw that cyclone had still not come, they thought it would not materialize and left the cyclone shelters for their homes. Many of these people fell victim to the fury of the cyclone. BMD came under heavy criticism for having forecasted landfall ahead of time. However, according to Mr. Shah Alam, Deputy Director of Climate Division of BMD, the Cyclone Sidr reduced its speed before approaching coastal landmass and accordingly BMD on 15th revised its bulletin. It forecasted that Sidr would hit Bangladesh coastline on the same day in the evening between 6 and 10 PM.
One thing has transpired from this fatal mistake of leaving the shelter early is that people should remain in the cyclone shelters until it has left the area. It is important that cyclone shelters should have the basic amenities so that people could stay there for few days. There should be adequate facilities for water, sanitation, sleeping space, generator lights, and paramedics at cyclone shelters. Provision must be made for food so that evacuees could have meals for at least two days either from their own sources or from the government. The government should deploy trucks, buses, inland vessels to evacuate people to the cyclone shelters, Upajila and Thana headquarters and arrange for their return. This will encourage people to heed to cyclone warnings because at present warnings are often ignored because of the hassle to move to cyclone shelters and wrong alarms. There is necessity to develop good road networks in the coastal region for easy movement. The government should make facilities for F.M. Radio broadcasts along the coast, which shall provide timely cyclone warning to coastal population.
There is dearth of cyclone shelters in the coastal region. Those that have been constructed (2,500) after the 1987 cyclone have worn out and require either major repairs or reconstruction. In densely populated areas, there should be bigger shelters. Existing government and public assets such as office buildings educational institutions, places of prayers should also be renovated to be used as cyclone shelters
Secondly, sea walls or cost effective earthen embankments along the coastline are good option to create defense against tidal bore. Sea walls will be equally effective against predicted sea level rise due to climate change. Instead of constructing sea walls entirely of concrete these could be made having concrete or brick lining on both sides with the hollow in the middle filled up by sand bags or just sand to make it a strong and effective barrier. At present, the low height embankments can hardly repulse a 10.6 meter (34.77 feet) high tidal bore like that of 1970. In coastal islands such as Hatiya, earthen embankments exist but they are not covered by trees to compensate their low height and sustain the impact of cyclone wind. Embankments could be constructed with the earth obtained from excavating large tanks in the coastal region. This will also meet the scarcity of fresh water immediately after a cyclone. Government should start a major programme for constructing embankments -- concrete, semi-concrete or plains earthen depending upon the degree of threat so that all inhabited coastal areas can be enclosed. In fact, even the Sunderbans forest requires embankments to protect its habitats of living species. Lives of many embankments have come to an end because some of them were constructed during Ayub Khan's time. Sidr has washed lot of embankments and they need to be reconstructed.
Sunderbun forest has saved many lives and destruction of property from the battering wind of Cyclone Sidr. Other options for protection includes extension of present Sunderban forest, which can help create a natural barrier against cyclone. Mangrove forest is very effective to dissipate the powerful force of waves. Once Sunderban forest extended up to Rajbari district in the North, (along the Padma river) and to the coastline of Patuakhlai district in the south east. During the British period, these areas were cleared for human habitation and cultivation. In the coastal islands and char areas along the coast, the government should bring all its khas lands under reforestation scheme. Emphasis should be given on thick vegetation from top to bottom. Coastal species of trees have mostly bare trunks, which make them unsuitable for facing combination of seawater and high velocity winds. Tall bamboo thickets can prove to be ideal for creating an impenetrable barrier. Cyclone wind is more destructive whenever there is open space. This could be sea fronts, watersheds, char lands, rivers, canals, paddy fields, water tanks, front or backyard of village homesteads. If we can encircle all these open spaces with thick forestation, the impact of wind can be lessened. Village people can be motivated to undertake voluntary efforts under community forest schemes.
Cyclone Sidr caused heavy damage to village homes. Weak structures were smashed to the ground. In coastal areas wider side of houses face the sea. The narrower side if faced seawards it can sustain far greater impact of wind. Moreover, they are built on mud platforms mainly by wooden frames. Instead low cost concrete pre-fabricated pillars at least 4”x 4” on each side should be used to build houses. Each of the pillars should have a foundation of four to five feet deep. Roofs of houses should be built not on wooden frames rather on iron angle bars so that tin sheets could be bolted rather than nailed. Wooden frames give away easily to powerful swirling winds. Government as well as NGO's should take the initiative to introduce these house-building materials for rural folks at a cost effective price. Interest free loans through co-operatives for reconstruction of homes could immensely help them.
There is an acute need for an integrated coastal zone management plan, not only to integrate cyclone preparedness and protection measures with the development plan of the area but also to give priority to such measures. We have seen the vulnerability of the coastal people to frequent cyclones. Their ability to revive and stand up against natural calamities has become seriously compromised due to precarious condition of the coastal region. Environmental degradation such as disappearance of mangrove forest, wanton felling of trees and wetland encroachments are causing ecological disaster making it more difficult to face threats from climate change. It is predicted that global warming will increase cyclones and they will become more powerful and harmful than the experienced ones. Western countries have moral responsibility for the consequences faced by the developing countries due to climate change and must come forward to reduce its effect. Bangladesh should make its concerns deeply felt before the international community so that international responses against climate change should complement the national measures to save the lives and livelihood of millions of people living in the coastal region.
Altafur Rahman is a Manager (Legal Department), National Housing Finance and Investments Ltd.