Mapping of flood areas using Sentinel-1 synthetic aperture radar (SAR) images with Google Earth Engine cloud platform – A case study of Chamoli district, Uttarakhand- India

Abstract

Flood inundation maps, which can be created using satellite images, offer useful information for flood risk preparation, control, communication, response, and mitigation during a disaster. This study discusses the Chamoli disaster, which occurred on February 7, 2021 in Uttarakhand state, India using Sentinel-1 data acquired pre, during, and post the flood to understand its impact on the region. This study also describes an automated flood inundation mapping method based on Sentinel-1 synthetic aperture radar (SAR) data using Google Earth Engine (GEE) platform. In this study, the backscattered product of SAR images after pre-processing from the GEE platform was used. For validation approaches both direct (field data) and indirect (secondary data) is used. Secondary data include optical Remote sensing images from the Sentinel-2 satellite, which were used in the study. For Sentinel-2 data processing ArcGIS has been used. The field data were obtained at different flood-affected areas on different time scales. To summarize, study results from Sentinel-1 SAR data using GEE can be a valuable method for monitoring flood inundation areas during a disaster, as well as enhancing existing efforts to save lives and livelihoods of populations, as well as safeguard facilities and industries.