Flood inundation mapping and monitoring in Kaziranga National Park, Assam using Sentinel-1 SAR data

Satellite-based flood assessment for extent and severity is very crucial input before, during, and after a flood event has occurred. Though optical remote sensing data has been widely used for flood hazard mapping, Synthetic Aperture Radar (SAR) data is preferred for detecting inundated areas and providing reliable information during a flood event due to its capability to operate in all weather and day/night time. Availability of cloud-free optical images during monsoon over north eastern India is a rarity. SAR data also has the advantage of detecting inundation under vegetated areas due to its penetration capabilities and sensitivity to soil moisture. The present study is an attempt to use SAR data for flood monitoring of the Kaziranga National Park (KNP) during monsoon, 2017. Every year, animals are washed away by floods and most of them migrate to higher grounds in order to escape from the rising water levels. Flooding events are common in the study area during the monsoon season due to high rainfall and its close proximity to the Brahmaputra River. Dual polarized (VV and VH) Sentinel-1 SAR images obtained for the entire monsoon period in 2017 were used to create inundation maps of the KNP. Two flood waves were observed in July and August, the second of which is considered to be one of the worst flooding events inundating most areas of the park. The use of SAR data for monitoring of flood events can be very crucial for identifying locations for building animal shelters and finding routes for rescue and relief operations during the disaster.