On 15 November 2007, a category 4 cyclone – code-named Sidr – came ashore in Bangladesh. Wind speeds reached 225 km/h; some waves were eight metres high. More than 3200 people died.
Bangladesh is a prisoner of its geography. Three rivers, the Brahmaputra, the Ganges and the Meghna rise in the Himalayan mountains before they converge into a vast delta and pour into the Bay of Bengal. Bangladesh is built over the flood plains of those three great rivers.
The flat land of each of the plains is fertile. As a result, the country is densely populated. Floods on any of the three rivers affect large numbers — in fact millions — of people.
When all three rivers run high – which happens often enough with monsoon rains and melting snow from the Himalayas – much of Bangladesh is under water. Most of the country is only between one and two metres above sea level.
So Bangladesh is caught – by rising sea levels; by the way that the Bay of Bengal narrows to a tip in the north, focussing the energy of ocean waves; by the wild storms whipped up in warm tropical water; and by shallow seas. These factors, conspiring with the Himalayan rivers, make for a lot of water. The only way it can escape is over the land where the people live.
Things are getting worse. Far to the north in Nepal, villagers have a different set of problems. With no fuel for their cooking fires, they are cutting down the forests. So instead of soaking into the ground, rains now rush down the valleys, increasing the flood risk.
In 1970, a category 3 storm made landfall in western Bangladesh. It caused 300,000 deaths, making it one of the most deadly natural disasters in modern history. The country also suffered catastrophic storms in 1987, 1988, and 1998.
In 1991 an estimated 138,000 people died as a result of a cyclonic tidal wave. A network of cyclone shelters and a warning system introduced after the 1970 disaster reduced the 1970 death toll by more than half.
The most recent flooding occurred mid-November 2007. More than 70 per cent of the land area was inundated. It damaged or destroyed over 12 million houses. More than 23 million people were affected.
Flooding has also hit the neighbouring Indian state of Assam, affecting close to 12 million people and killing about 180.
In Nalbari district, 241 villages were submerged completely. In addition to severe shortages of drinking water, the spread of diseases such as bronchitis and diarrhoea caused a large number of fatalities.
But the people of Bangladesh are fighting back. The government sees early warning systems as extremely important in overcoming such frequent threats to the lives and economy of the country. They will enable the people and government to take action to prevent greater loss of life.
A newly established operations co-ordination room in the Disaster Management Bureau, and the Flood Forecasting and Warning Centre in the Bangladesh Disaster Preparedness Centre were the principal organisations involved in these initiatives. They used satellite remote sensing imagery in disaster reduction and management.
Monitoring, control and management of such widespread calamities requires continuous observation of the area. As a result, space technologies – such as remote sensing, GIS, GPS and communications – play a useful role.
In November, national, regional and global disaster relief and humanitarian organisations were mobilised. They provided sources of information and data collection. They also secured robust communications networks for managing, controlling and monitoring the disaster.
At a local level, the Bangladesh Meteorological Department used satellite images of the cyclone to track its movement.
The Bangladeshi branch of Habitat for Humanity was also active. It operates mainly through Habitat Resource Centres and related satellite centres in local communities. Its charter is to rehabilitate people hit by disasters.
The World Food Program distributed high protein and energy biscuits, rice and polypropylene bags.
Much of this was possible because on 15 November, the United Nations Office for Outer Space Affairs activated the UN International Charter on Space and Major Disasters. This is a program created to provide the international community with enhanced access to satellite imagery and GIS services.
The project was managed by the Zentrum fur Satellitengestutzte Kriseninformation. ZKI is the centre for satellite based crisis information which is part of the German space agency, Deutsche Zentrum fur Luft und Raumfahrt. DLR’s remote sensing data centre specialises in rapid acquisition, processing and analysis of satellite data. Its analysis is tailored to meet the specific requirements of national and international political bodies, and of humanitarian relief organisations.
The data applied by ZKI was 10 metre-resolution Spot and 16 metre resolution TerraSAR-X imagery. TerraSAR is a new high-resolution radar satellite managed by Infoterra.
The European Space Agency was also involved. Under its Earth Watching Project, ESA uses satellite remote sensing to monitor emergencies as they happen.
ESA’s European Space Research Institute and Eurimage started the project in 1993 to supply satellite data and pertinent information quickly in times of natural disasters. It is able to keep track of floods, alert coastguards to pollutants in the water, detect fires or assist in rebuilding after disasters.
Cyclone Sidr was monitored by Earth Watching using data collected by the Advanced Synthetic Aperture Radar and the Medium Resolution Imaging Spectrometer instruments on Envisat.
The exercise proved the effectiveness of radar imaging at times when the region is cloudy. Both ASAR and TerraSAR-X proved extremely useful during the operation. The Hawaii based Pacific Disaster Centre also monitored the advent of Sidr and its behaviour. PDC works for the development of more effective policies, institutions, programs, and information products. It provides help in disaster management, and humanitarian assistance for communities in the Asia Pacific region and beyond. The cyclone was also monitored by the US Earth Observatory and Natural Hazards Program of NASA, the National Oceanic and Atmospheric Administration, and the US Geological Survey.
Different sensors aboard a variety of satellites continuously watched the calamity’s dimensions. For instance, data from the Moderate Resolution Imaging Spectro-radiometer on NASA’s Terra satellite was used, as was the Tropical Rainfall Measuring Mission, a joint initiative of NASA and the Japanese Space Agency.
Sidr was a disaster, but it was not as bad as it might have been. The challenge is to learn from such experiences so that the next time, even fewer people die. Because there will be a next time. The Bangladeshi people continue to live with their geography.