Flood mapping is an essential component of planning flood mitigation. The availability of remote sensing data makes rapid flood mapping possible. This article develops an accurate method for rapid flood mapping using satellite imagery. Sentinel-2 imagery was tested by acquiring data before and after a flood event in a lowland area. Flooding extraction was performed using the newly developed Flood Inundation Extraction Index (FIEI) and compared to the Modified Normalized Difference Water Index (MNDWI), the most commonly used index. Based on the choice of threshold, the results are divided into flooded and non-flooded areas. Evaluation of the performance accuracy based on the total and kappa coefficients showed that the FIEI approach is more accurate than the MNDWI approach.

The existence of a flood inundation rapid map is needed in flood mitigation. This research is intended to map flood inundation quickly by utilizing satellite image technology. Sentinel 2 Level 1C technology uses before and after the flood. The extraction process uses the methods of NDWI (Normalized Difference Water Index) and MNDWI (Modified Normalized Difference Water Index). The result is treated with a threshold value by dividing the pixel value into flooded and unflooded areas. The performance model shows that the MNDWI method is more accurate than the NDWI method in producing flood inundation maps. Thus, the results of the MNDWI method are practical and able to map flood inundation quickly.