Flood Mapping and Simulation using Sentinel 2 and SRTM Data

Abstract

Flood is one of the most devastating natural disasters occurring and affecting lives and economies globally. Hazards associated with floods are linked to storms raging across continents and anomalously high rainfall that impacts largely low-lying terrains. Addressing and managing flood is challenging and these require concerted efforts in technology that is crucial in finding a lasting solution. This require reliable and up to date data which must include accurate topographic information of affected areas. Flood inundation can be mapped and probability of occurrence can be simulated using digital elevation model (DEM). In this work, flood event of November 2019 was mapped and compared with normal water level of River Benue and the adjoining Lakes Gerio and Njuwa using Sentinel 2 MSI. Results show that the flood event engulfed the two lakes and expanded into the riverine wetland covering nearly 450% of area covered by normal water conditions. Simulated results show that at 157m above sea level, flood event can exactly replicate the November 2019 flood, expanding and covering the whole wetland. This result is important in determining rates of inundation by prediction of future events. The simulated results could also serve as a base data for engineering-based hydrologic flood models such as Hydrologic Engineering Centre - Hydrologic Modelling System (HEC-HMS) and Hydrologic Engineering Centre - River Analysis System (HEC-RAS). It is recommended that high resolution DEM would be required to enhance accuracy of flood models such as Light Detection and Ranging (LiDAR), Synthetic Aperture Radar (SAR), and Interferometric SAR (IFSAR) that has resolutions between 1-10m.

Keywords: Flood, Simulation, Sentinel 2, DEM, Mapping, Yola.