Delineation of Frequently Flooded Areas Using Remote Sensing: A Case Study in Part of Indo-Gangetic Basin

Abstract

AbstractRemote sensing is a useful tool for flood monitoring and damage assessment. Unlike traditional survey methods, it provides cost-effective solution with wider coverage and frequent revisit cycle. In general, coarser sensors provide high repetitivity with lower spatial resolution, whereas constellation of finer spatial resolution sensors can be useful in continuous flood monitoring. Different methods and techniques are used for delineating the flood extent and damage assessment based on the type of sensors. Hence, it is necessary to carry out a detailed and in-depth review of remote sensing technologies and approaches available for processing and analysing satellite data for flood response studies. In the present study, automated procedures were used for generation of flood layers and flood persistence maps at Gram panchayat level in the part of Indo-Gangetic plains, Uttar Pradesh. Further, attempt was made to plan the measures that can be useful in relief operations based on the detailed analysis of persistence maps. Methods based on thresholding were improvised by applying unsupervised classification and online Geo-processing platform of Google Earth Engine. Historical flood events for the period 2010–2020 were generated over part of Indo-Gangetic basin and integrated with administrative layers for identifying the villages vulnerable to floods. Accuracy of flood maps were improved by applying the conditioning factors to remove misclassification of flood extents. Particularly, villages located in Ghazipur, Allahabad, Ballia, Gorakhpur, Bahraich and Balrampur districts of UP state indicated high Flood Vulnerability Index (FVI) values. FVI computed at village level using the historical flood events can be of great help for identifying and planning relief shelter locations in the study area. Remote sensing and GIS technologies were successfully envisaged in the identification and planning of relief shelters for the most vulnerable villages.KeywordsOptical sensorMicrowave sensorRemote sensingFlood vulnerability indexFlood monitoring and damage assessment