Satellite-Based Flood Mapping for Impact Assessments: A Case Study in Lokoja, Kogi State, Nigeria
In recent years the quantity and quality of satellite remote sensing data available to researchers during and after an event has greatly improved. In this study, the change detection and histogram thresholding method was used to extract the flooded areas from Sentinel-1 SAR (Synthetic Aperture Radar) data in order to assess the impact of flooding caused by heavy rainfall that took place in Lokoja, Kogi State from 23rd August to 28th September, 2018. The extracted flooded areas were overlaid on the world imagery base layer hosted by AGOL (ESRI’s ArcGIS Online) and Google Earth global platform in order to assess the flood impacts on the environment. The results revealed that 211 buildings (including shops, supermarkets, hotels, churches and mosques), 3 major roads and 317sqkm of farmlands were adversely affected especially in the month of September. These results confirm the statistical flood impact information released on the 9th of September, 2018, by the Kogi State Emergency Management Agency.
Keywords- Flood, mapping, Sentinel-1, Satellite imagery, Remote sensing.