Bihar, India’s most flood-prone state, is under constant threat of flooding. Every year, floods destroy lives, livestock, infrastructure and bring with them a huge financial toll.

During disasters, obtaining reliable information is crucial, according to Bihar State Disaster Management Authority (BSDMA), whose mandate is to design disaster risk reduction plans and policies as well as long-term preparedness. One key challenge for BSDMA is the mapping and monitoring of flood-affected villages.

New district-level mapping of flood-prone areas was established in Bihar with the help of the International Centre for Integrated Mountain Development (ICIMOD).

This August, with the support of the Australian Government’s Department of Foreign Affairs and Trade (DFAT) through the Sustainable Development Investment Portfolio (SDIP), ICIMOD’s

Using the Phased Array type L-band Synthetic Aperture Radar (PALSAR), KBP and JAXA were able to generate near real-time flood information and damage assessments. PALSAR has the capability to map flooding 24/7, in all kinds of weather.

ICIMOD KBP coordinator and hydrology expert Shahriar Wahid said mapping and monitoring floods can be highly challenging using optical remote sensing data, especially as floodwaters are rising.

‘Most images are obstructed by clouds as the majority of satellites are optical and cannot penetrate clouds which tend to occur over flooded areas,’ Dr Wahid said.

PALSAR has been instrumental in overcoming those obstacles and was recently used in August to prepare thirty-three district inundation maps at the height of flooding in Bihar. ICIMOD and JAXA provided a quick estimate of the inundated areas including agricultural, grassland, barren area, built-up area and fishponds. Floodwaters had engulfed 18,755 sq. kms leaving ninety-four percent of agricultural lands affected.

‘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, Environment and Climate Change, BSDMA. He said the maps would be useful to Bihar Government’s Disaster Management Department (DMD), which is involved in search and rescue operations and distributes relief and manages flood-relief camps.

Flood maps illustrating village-level inundation have the potential to support BSDMA in several community-level risk reduction activities. Such information is crucial to the government’s smooth response to flood management as waters continue to rise in Bihar.

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