Flood Impact Assessment in Koton Karfe Using Sentinel-1 Synthetic Aperture Radar (SAR) Data

Abstract

Flood has proven to be an incessant menace in Nigeria more threatening to riverine areas. The most recent flood ensued in 2022 as a result of heavy rainfall and the release of water from Lagdo Dam in Cameroon which became very devastating in many areas notably the Koton Karfe area in Kogi State, causing business shutdowns and the loss of lives and properties. In this work, Sentinel-1 Synthetic Aperture Radar (SAR) imagery was used for flood inundation mapping, and the accompanying damages were investigated using Landsat derived Land cover maps of Koton Karfe during the 2022 devastating flood. Overall, the results obtained in this study show that the regions that felt the impact of the flood the most were the southern and western areas, which must have experienced such an impact due to their proximity to the rivers Niger and Benue and also the water coming from the upper stream part of Cameroon. Further findings revealed that during the flood period on October 13, 2022, the total inundated area in Koton Karfe was estimated to be 198.255 sq. km. In terms of damage assessment, the urban areas had reduced from 220.902 sq. km in May 2022 to 87.473 sq. km in November 2022. This shows that over 133 sq. km of the urban settlement have been lost, indicating that lives must have been lost, properties too, and humans must have been displaced. This research will assist in the space of flood emergency response and disaster management.

Futuristic prediction of the lagoon coast shorelines using spaceborne Synthetic Aperture Radar (SAR) imagery

“…Sadly, the imagery is created by passive sensors, which have several limitations, including the inability to retrieve data at night, a high cloud cover percentage, and a low spatial resolution of 30 meters, which determines the horizontal accuracy of the data (Gens, 2010). The European Space Agency (ESA) recently developed Sentinel-1 Synthetic Aperture Radar (SAR), a tool that has been effectively used to monitor flooding (Carreño and De Mata, 2019;Qiu et al, 2021;Isiaka et al, 2023) and changes in the shoreline (Zollini et al, 2019;Bartsch et al, 2020;Zhu et al, 2021) with characteristics ability to produce image at night, through cloudy-skies or during extreme storm events with as low as 5 m spatial resolution which are some of it advantages over the passively sensed imagery. They also have a range of applications aside from the monitoring of coastal hazards but specific to coastal hazard monitoring are Synthetic Aperture Radars (SAR), LiDARs, Radar altimetry and scatterometers (Melet et al, 2020).…”