FLOOD EXTENT MAPPING USING GEOSPATIAL TOOLS

Floods have caused tremendous destruction of lives and properties in communities along different rivers in Chikwawa district. This paper is an application of Remote Sensing and Geographic Information System in mapping the extent of floods using Sentinel-1 satellite imagery provided by European Space Agency (ESA). The central focus of this project revolves around production of flood extent map, calculation of flood inundation area, and production of an exposure map for the January 2022 flood event that was caused by cyclone Ana. Sentinel Application Platform (SNAP) and ArcGIS 10.8 were the image processing and GIS applications used. The procedure consisted of collection of two sentinel-1 datasets, one for pre-flood event (21 October, 2021) and the other during the flood event (26 January, 2022). Pre-processing steps, which consisted of calibration, speckle filtering, terrain correction and stacking were applied to the images in SNAP software. The results revealed that most of the areas lying close to the Shire River are highly exposed to the floods and the floodwater covered a significant amount of area. Sentinel-1 SAR earth observation data has a tremendous potential for creating flood information with high accuracy and high spatial resolution due to the prevalence of severe weather conditions during flooding season. Improvements in flood mapping can be a vital tool mitigating disasters.