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17-Apr-2014

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N° 30–1999: Eyes in space monitor floods in Bangladesh

20 July 1999

Since July 11, when river levels rose dramatically due to heavy monsoon rains and several embankments gave way, Bangladesh has once again been battling against floods, affecting half a million people and one tenth of the nation's territory. To assist local authorities in coping with this natural disaster, a local receiving and processing station is ready to provide near real-time flood information derived from data transmitted by radar imaging systems on board ESA's ERS Earth observing satellites.

This low-cost station, dubbed RAPIDS for Real-time Acquisition and Processing Integrated Data System, funded by British and Dutch national co-operation programmes, covers the Ganges and the Brahmaputra-Jamuna floodplain. Installed at Dhaka by the Dutch national aerospace research institute NLR, Synoptics (NL), BURS (UK) and NRI (UK), the station is operated by Bangladeshi experts, working with the Bangladesh Water Resources Planning Organisation.

These operations have been made possible by an ESA-funded project, covering six months of ERS data acquisition, processing and associated training activities, under the Data User Programme, an optional programme of the Agency, funded by Belgium, Switzerland and the Netherlands.

This project is a practical demonstration of Europe's commitment to putting space technology to effective use on behalf of the developing countries most severely affected by major catastrophes. Bangladesh was hit last year by the worst flood of the century, which killed over 1200 people and caused economic loss of more than two billion euros.

The Synthetic Aperture Radar (SAR) imager on board ERS-1 and ERS-2 is particularly well suited to monitoring floods over large areas since it penetrates clouds and operates day and night. The archive images attached cover a 100x100km area, where the Ganges (left) and Brahmaputra or Jamuna (top) rivers converge in Bangladesh (right). The images are an example of one of the techniques used in flood mapping. The first is a multi-date, false colour image derived from three black and white SAR images taken before and during the flood. The colours in image 2 distinguish between the flooded (blue) and non-flooded (brown) areas with the normal riverbeds in black, following analysis and interpretation of the multi-date image. This information is then matched against a digital elevation model to derive water levels and estimate the duration of the flooding.

Over the long term, the radar image archive on Bangladesh in the monsoon season will facilitate mapping of hazards in areas where the population fishes and farms (growing rice in particular), when the floodplain is subject to unusual flooding or droughts. The radar archive also serves to identify river migration and coastal processes due to the yearly monsoon and flooding.

ESA's ERS-1 and ERS-2 Earth observing satellites, launched in 1991 and 1995, have been collecting a wealth of valuable information on the Earth's land surface, oceans, sea ice, polar caps and atmosphere. Europe's future contribution to addressing worldwide environmental problems comes in the shape of Envisat.

This sophisticated satellite to be launched in 2000 by an Ariane 5, will provide users with even more refined and specialised remote-sensing data to chart and document changes in our environment and will supply reliable information for better management of natural or man-made disasters.

For further information, please contact:
Franca Morgia, ESA/ESRIN Public Relations
Tel. + 39 06 9418 0950

Colour copies of the images are available on request or can be downloaded from our Image Gallery on the web at
http://www.esa.int/gallery/, subject "Earth Observation Result"
More info on ESA on the web at http://www.esa.int


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