Operational Flood Mapping Using Multi-Temporal Sentinel-1 SAR Images: A Case Study from Bangladesh

Abstract

Bangladesh is one of the most flood-affected countries in the world. In the last few decades, flood frequency, intensity, duration, and devastation have increased in Bangladesh. Identifying flood-damaged areas is highly essential for an effective flood response. This study aimed at developing an operational methodology for rapid flood inundation and potential flood damaged area mapping to support a quick and effective event response. Sentinel-1 images from March, April, June, and August 2017 were used to generate inundation extents of the corresponding months. The 2017 pre-flood land cover maps were prepared using Landsat-8 images to identify major land cover on the ground before flooding. The overall accuracy of flood inundation mapping was 96.44% and the accuracy of the land cover map was 87.51%. The total flood inundated area corresponded to 2.01%, 4.53%, and 7.01% for the months April, June, and August 2017, respectively. Based on the Landsat-8 derived land cover information, the study determined that cropland damaged by floods was 1.51% in April, 3.46% in June, 5.30% in August, located mostly in the Sylhet and Rangpur divisions. Finally, flood inundation maps were distributed to the broader user community to aid in hazard response. The data and methodology of the study can be replicated for every year to map flooding in Bangladesh.

Operational Monitoring and Damage Assessment of Riverine Flood-2014 in the Lower Chenab Plain, Punjab, Pakistan, Using Remote Sensing and GIS Techniques

“…Secondly, existences of cloud cover can restrain the availability of flood instances images. Certainly, SAR (Sentinel 1,2,3) and RADAR satellites can easily penetrate clouds and acquire images in comparison to optical satellites (Landsat, MODIS) [26,58]. In our cases, the free SAR data were not available and the study area was entirely cloud free during the 2014 flood, since the causative meteorological events happened in upper Chenab plain.…”

A General Overview of the Risk-Reduction Strategies for Floods and Droughts

“…Recent studies have applied satellite images for flood detection or flood mapping [103,104]. This approach is particularly helpful for those areas or countries without adequate ground-based observations [105,106]. The improvement in radar observation techniques in dual-polarization radar instead of single-polarization radar provides more accurate rainfall estimation [107].…”

Hydrological/Hydraulic Modeling-Based Thresholding of Multi SAR Remote Sensing Data for Flood Monitoring in Regions of the Vietnamese Lower Mekong River Basin

“…Hence, in this study we attempted to calibrate the HEC-RAS model elaborately, even though the main study focus was the optimization of the SAR-based water extraction thresholding. In addition, as there are many hydrological/hydraulic models available, choosing appropriate model types and scales to generate reliable results of final satellite-based flood inundation maps was imperative, as supported by Prestininzi et al (2011) [44]. Figure 13.…”