Flood inundation mapping using Sentinel-1A in An Giang province in 2019

Abstract

An Giang is one of the provinces in the Mekong delta that is greatly affected by flood events, which brings damage and devastation to life and property. This study practices the application of Sentinel-1A images to monitor the distribution of flood depths in the An Giang province in 2019 as well as applies regression correlation and thresholding to scattering value analysis. The research results indicated the exponential regression model on the VV polarization images had correlation coefficients (r) in August, September, and October ranging from 0.8398 to 0.9764 and determination coefficients (R²) ranging from 0.7896 to 0.9533. Results from the map of current flood depth showed that the flood depth ranged from 0-250 cm, which corresponded to four flood levels. The flood area increased from August to October with the largest flooded area being 89,606.82 ha (accounting for 26.15%) mainly on rice lands and in eight urban districts including An Phu, Tinh Bien, Chau Thanh, Chau Phu, Phu Tan, Tri Ton, Chau Doc, and Long Xuyen city. The limit of flood depth determined by using the Sentinel-1A images was below 145 cm. Above this value, the scattering in the image is not significantly different from the actual submerged depth.