TITLE:
Flood Mapping in Mozambique Using Copernicus Sentinel-2 Satellite Data
AUTHORS:
Yaw A. Twumasi, Edmund C. Merem, John B. Namwamba, Abena B. Asare-Ansah, Jacob B. Annan, Zhu H. Ning, Rechael N. D. Armah, Caroline Y. Apraku, Harriet B. Yeboah, Julia Atayi, Matilda Anokye, Diana B. Frimpong, Ronald Okwemba, Olipa S. Mwakimi, Judith Oppong, Brilliant M. Petja, Janeth Mjema, Priscilla M. Loh, Lucinda A. Kangwana, Valentine Jeruto, Leah Wangari Njeri, Joyce McClendon-Peralta
KEYWORDS:
Tropical Cyclones, Floods, Remote Sensing, NDWI, Exponential Smoothing (ETS), Digital Elevation Model (DEM), Sentinel-2 Satellite, Mozambique
JOURNAL NAME:
Advances in Remote Sensing,
Vol.11 No.3,
October
31,
2022
ABSTRACT: Over the last two decades, Mozambique has experienced tremendous tropical cyclonic activities causing many flooding activities accompanied by disastrous human casualties. Studies that integrate remote sensing, elevation data and coupled with demographic analysis in Mozambique are very limited. This study seeks to fill the void by employing satellite data to map inundation caused by Tropical Cyclones in Mozambique. In pursuit of this objective, Sentinel-2 satellite data was obtained from the United States Geological Survey (USGS)’s Earth Explorer free Online Data Services imagery website covering the months of March 20, 2019, March 25, 2019, and April 16, 2019 for two cities, Maputo and Beira in Mozambique. The images were geometrically corrected to remove, haze, scan lines and speckles, and then referenced to Mozambique ground-based Geographic: Lat/Lon coordinate system and WGS 84 Datum. Data from twelve spectral bands of Sentinel-2 satellite, covering the visible and near infrared sections of the electromagnetic spectrum, were further used in the analysis. In addition, Normalized Difference Water Index (NDWI) within the study area was computed using the green and near infrared bands to highlight water bodies of Sentinel-2 detectors. To project and model the population of Mozambique and see the impact of cyclones on the country, demographic data covering 1980 to 2017 was obtained from the World Bank website. The Exponential Smoothing (ETS) method was adopted to forecast the population of Mozambique. Results from NDWI analysis showed that the NDWI is higher for flood areas and lower for non-flooded ones. The ETS algorithm results indicate that the population of Mozambique would nearly double by 2047. Human population along the coastal zone in the country is also on the rise exponentially. The paper concludes by outlining policy recommendations in the form of uniform distribution of economic activities across the country and prohibition of inland migration to the coastal areas where tropical cyclonic activities are very high.