Researchers use satellite data for flood mapping

Peak rise of 5 m in water level in Kuttanand, 10 m in kole lands

A joint team of researchers from the University of Kerala and the Michigan Technological University, USA, have come out with an inundation map using satellite images to assess the extent of flooding that caused widespread devastation in Kerala last month.

The team comprising Sajin Kumar, Assistant Professor, and Vishnu C.L., Research Associate, University of Kerala, and Thomas Oommen, Associate Professor, Michigan Technological University, used the data from the European Space Agency’s radar satellite Sentinel to map the inundated areas in Kerala during and following the floods.

“The map shows that the wetlands consisting of low-lying Kuttanad in the south, the kole lands of Thrissur in the north, and the backwater system experienced significant increase in water level owing to the floods triggered by torrential rains. While the floodwater in most of the inundated land had already begun receding by August 21, the water level in Kuttanad and the kole lands were slow to decrease,” Dr. Kumar told

The Hindu .

The team followed up the mapping with a field visit to Kuttanad to validate the data. The results showed a 95% accuracy. The analysis also showed a peak rise of 5 m in the water level in the Kuttanad region, going up to 10 m in the kole lands.

Cloud-penetrating ability

Radar satellites, with their cloud-penetrating capability, offer a significant advantage for flood inundation research. “Unlike other natural hazards, data on the extent of flooding need to be captured before the water recedes. Hence only radar images come in handy as other optical satellite images will be marred by cloud cover,” explains Dr. Kumar.

The team is also in touch with the Canadian Space Agency to enlarge the database on the flood situation in Kerala.

The researchers point out that changes in land use, conversion of wetland to dryland, unbridled mining of river sand and brick clay, and construction activities in the floodplains had played havoc with Kuttanad and the kole lands and affected the natural drainage system.

Dr. Kumar said the inundation mapping would help in scientific redevelopment of the affected areas by introducing zoning regulations. He calls for a State-level geo-hazard assessment for disaster risk reduction.

The research team is currently in Idukki to collect field data on the damage caused by the landslips and flash floods in the district.