Feasibility of Temporal Monitoring of Flood Inundated Areas and Crop Damage Assessment using Multi- polarised Temporal SAR Data without any Ground Truth Campaign

Floods are catastrophic events and lead to huge loss of lives and property. Quick assessment and mapping of area affected by the flood water and monitoring of flood event is very important for proper planning and timely rescue operations. Remote sensing technique plays a very important role to achieve these goals as remote sensing image (data) covers large area and the data can be analyzed quickly to provide timely assessment of flood events. However, many times, flood event is associated with rainy and cloudy conditions. Therefore, it is difficult to acquire optical remote sensing images over the flood affected areas. Synthetic Aperture Radar (SAR) ensures uninterrupted satellite data supply as due to longer wavelengths, SAR signal can penetrate rain and clouds. Therefore SAR data is a right choice for flood monitoring and assessment. In this study, monitoring of various flood events along with assessment of crop damage has been done for Khagaria district of state of Bihar in India. Highlight of the study is that the entire study has been carried out without any ground truth campaign. This has been achieved with the help of twelve days and few twenty four days temporal SAR data sets acquired by Sentinel-1 SAR over Khagaria district during monsoon season of year 2016 and 2017. Ground truth information has been compensated by information available in the published literature and basic understanding of interaction of SAR signal with various earth targets especially surface water and vegetation. Change detection analysis has been performed to compare change in flood inundation area from 2016 to 2017 for Khagaria district. In order to make the study more inclusive, crop damage assessment have also been conducted for Khagaria district with the help of crop maps taken from literature. Comparison of area under crop damage for the year 2016 and 2017 has also been included in the paper. Keywords: Feasibility, flood inundation area, SAR, temporal monitoring