Satellite Technology: Mapping and Predicting Floods in India


SEATTLE — New satellite technology is equipping authorities with almost real-time information to guide their efforts in predicting floods in the most vulnerable areas.

The north-eastern Indian state of Bihar faces overwhelming rainfall every year. The Bihar floods submerge roads and houses, destroy crops and livestock. The country’s disaster management authority struggles to assess damage, evacuate people in time and distribute aid effectively.

Bihar borders on Nepal, right at the foot of the Himalayas. According to the India Meteorological Department, between 2004 and 2010, the average rainfall for July and August was 13.5 inches and 10 inches respectively, far exceeding the average 7 inches faced by the densely populated areas of O’Ahu island, Hawaii, the US’s rainiest state. Over 70 percent of Bihar’s area is at risk of being deluged by rainfall every year.

In the past, the people of Bihar lived in the highest parts of the state and used the lowlands to collect the water that is useful during the dry season. However, rapid and unplanned urbanization, as well as illegal sand mining, have situated thousands of people in harm’s way.

Since the beginning of the floods in July, 249 people were reported dead and over 317,000 have been evacuated from their homes.

The new satellite technology is utilized in the form of a mapping program that was developed by the International Centre for Integrated Mountain Development (ICIMOD), an agency promoting development in the Hindu Kush Himalayas, for the Bihar State Disaster Management Agency (BSDMA). It monitors 33 of Bihar’s 38 districts, devising flood maps that are circulated through an online flood information system.

It speeds up the response to an imminent crisis, damage assessment, risk management and aid distribution officials at the ICIMOD stated.

“Traditionally, field teams are organized and dispatched to flooded areas to map floods. This can be time-consuming and operationally difficult during a flooding event,” Shahriar M. Wahid, a senior hydrologist at the ICIMOD told Reuters.

In the Himalayan area near Bihar, monsoons bring thick clouds that cannot be penetrated by optic-based satellites. If torrential rain that triggers flash floods occurs in Nepal, the residents of Bihar can expect inundations within eight hours.The program developed by the ICIMOD uses satellite technology that penetrates cloud cover, namely the Phased Array type L-band Synthetic Aperture Radar (PALSAR), which is able to map floods in all kinds of weather, 24/7.

Satellite technology is not enough to give early warning to the residents at risk. The ICIMOD program runs the data through flood simulators that take into account geography, creating flood forecasts five to six hours after the raw satellite data has been received.

The maps are then circulated to government officials and relief agencies via satellite communications.

“Bihar Inter Agency Group (BIAG) members, namely international non-governmental organisations and United Nations agencies, are currently assessing the impact of floods in Bihar in the affected districts, and naturally this flood map would be extremely helpful for them,” said Asif Shahab, Project Officer at the Environment and Climate Change division of the BSDMA.

The data will also be used to determine the amount of crop insurance payments once the Bihar floods are over, Dr. Wahid said.

Satellite technology is used extensively in crisis response, but in developing nations such as India, the cost is high. With the support of the Australian government and the Japanese Aerospace Exploration Agency, ICIMOD is in a position to obtain satellite data at no cost.

The satellite maps can also be used as a prevention aid for years to come, as they can act as a template of how the Bihar floods behave in the future.

The challenge for the future is accounting for global warming and other changing environmental factors, such as deforestation and expanding urban centers.

Eliza Gkritsi

Photo: Flickr


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