# Comparative Impact Analysis of Cyclone Ana in the Mozambique Channel Using Satellite Data
## 3 Results
However, overall, the urban areas impacted by flooding accounted for a small percentage of overall flooded areas, with a relative percentage of 1.4% in Mozambique compared to less than 1% in Madagascar. This is relatively negligible and could only be observed at a very fine scale on this study's 10 m resolution maps, and was therefore not included in visualizations. The NDVI Index was calculated and visualized for both Madagascar and Mozambique as a measure of degradation. Changes in NDVI were observed in both countries' ROIs before vs. after the TC season. In Mozambique, changes in mangrove degradation specifically, with a before compared to after the cyclone season method, were minute (-changes of 0.1 in NDVI). This was despite some local increases in the patchiness of mangroves near already-barren areas and some local degradation. In Madagascar, in the Boeny region, mangrove areas displayed more degradation than the Melaky region and Mozambique overall. The majority of changes in NDVI could be seen in Bombetoka Bay, which flows into the Mozambique Channel, with differences in NDVI of 0.2-0.3. As can be seen in Figure 5, the comparison of this mangrove area shows a lower NDVI overall immediately after the cyclone season compared to before the season. Some stagnant bodies of water also appear to have been created south-west of Bombetoka Bay. Figure 4: Flooding Model and Related Exposed Population in the Sofala and Zambezia Provinces, Mozambique for TC Ana between 23 and 25 January 2022 (10 m resolution). Data was predicted using Sentinel-1 SAR GRD data and World Population Hub data. The areas with the highest number of people affected per km\({}^{2}\) in Mozambique occurred in areas around the Zambezi River in the Sofala province in riverside cities such as Caia and Marromeu, which can be seen in light yellow. Figure 5: NDVI Comparison between before vs. after Cyclone Season in Bombetoka Bay, Madagascar-the country’s largest remaining mangrove ecosystem using Sentinel-2 data. Areas in purple are areas with water components such as rivers or flooded areas. Dark green represents areas with high NDVI and healthy tropical vegetation, while light green represents areas that tend to be more barren, degraded and less healthy. Overall, mangrove forests tend to have been more degraded after cyclone season, patchy and bodies of stagnant flooded areas have also appeared. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Region** & **Area Affected by Flood (ha)** & **Relative Area Flood (\%)** & **Number of Exposed Population** & **Relative** & **Affected Population** & **Relative Urban Areas** & **Affected Urban Areas** \\ \hline
**Mozambique** & Zamperia & 595,872 & 5.78\% & 87,577 & 1.71\% & 6741 & 1.13\% \\  & Sofala & 456,120 & 6.71\% & 108,400 & 4.80\% & 7860 & 1.72\% \\
**Madagascar** & Boeny & 451,731 & 14.55\% & 66,591 & 7.15\% & 4042 & 0.89\% \\  & Melaky & 254,984 & 6.56\% & 12,412 & 4.01\% & 767 & 0.30\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparative Summary Table of the Flooding Model, Including Modelled Exposed Population and Urban areas. Relative areas for flooded areas, exposed population and urban areas were calculated as a percentage of total region area, total regional population, and regionally flooded area respectively. The distance of exposed populations to healthy mangrove forests has been computed and can be visualized in Figure 5 below in the Sofala region.