Cyclone Chido à Mayotte : une méthode rapide et reproductible par télédétection pour évaluer l'impact sur les mangroves

Cyclone Chido à Mayotte : une méthode rapide et reproductible par télédétection pour évaluer l'impact sur les mangroves

by Mollies Julie, Lafaye Claire, Catry Thibault, Gollety Claire, Jeanson Matthieu, Macera Lisa, Mouquet

Life & Natural Systems Science — General & History PDScience: general issuesPDMScientific research
🎙 Mollies Julie, Lafaye Claire, Catry Thibault, Gollety Claire, Jeanson Matthieu, Macera Lisa, Mouquet 👥 12K 📅 October 3, 2025 ⏱ 18 min 👁 70 📄 original study 🧭 2026-08-16
Available in: English (current) Français

Keywords

NDVISentinel-2mangrovecycloneremote sensing

Summary

This presentation, given by researchers from UMR Espace Dev, University of Mayotte, and UMR Marbec, introduces a rapid and reproducible remote sensing method to assess the impact of Cyclone Chido on the mangroves of Mayotte. The context is provided: Mayotte has 735 hectares of mangroves across 29 stands, hosting eight species of mangrove trees. These ecosystems provide essential services but face pressures from population growth and climate change. The cyclone caused severe damage, as shown in before-and-after photos. The method uses time series of NDVI from Sentinel-2 imagery, which is freely accessible with a 5-day revisit. A Python-based open-source chain downloads images, computes NDVI, and masks clouds. The NDVI time series from September 2024 to July 2025 were divided into pre-cyclone, post-cyclone, and recovery periods. Three analyses were performed: NDVI differences between periods, ANOVA tests on grouped mangroves by geographic area, and spatial mapping of NDVI changes. Results show significant impact in northern mangroves, consistent with the cyclone’s trajectory, and some recovery in eastern mangroves. The method is simple, reproducible, and complementary to field surveys. Limitations include cloud cover and small mangrove areas. Future work includes higher-resolution monitoring and integration into the Chido Mangrove project.

195 words

Critical Evaluation

Value of the Information & Strength of the Argument

The presentation provides valuable information on a practical method for rapid impact assessment of cyclones on mangroves using freely available satellite data. The argumentation is solid, as the method is clearly explained, and results are supported by statistical analysis (ANOVA) and spatial mapping. The authors acknowledge limitations, such as cloud cover and the inability to distinguish species or structure, which adds credibility. The method is presented as a tool for managers, and its reproducibility is emphasized. The discussion with the audience further clarifies methodological choices and potential biases.

97 words

Title / Content Match

The title accurately reflects the content, which presents a remote sensing method to assess cyclone impact on mangroves.

Quality & Reliability

8/10

The study is based on a well-established remote sensing method (NDVI from Sentinel-2) and includes statistical analysis (ANOVA) and spatial analysis. The methodology is clearly described, and limitations are acknowledged. However, the presentation is a conference talk, and the results are preliminary, with no peer-reviewed publication cited.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

  • Copernicus Open Access Hub — Source of Sentinel-2 satellite images used in the study.
  • Sentinel-2 Mission — Description of the Sentinel-2 satellite mission providing multispectral imagery.

Concurring Sources

  • Copernicus Open Access Hub — The study uses Sentinel-2 data from Copernicus, which is a reliable source.

Contribution & Novelties

The main contribution is a rapid, reproducible, and open-source remote sensing method to assess cyclone impacts on mangroves at a territorial scale, using NDVI time series from Sentinel-2. This allows for quick identification of the most affected areas and monitoring of recovery, which is crucial for management and restoration. The method is complementary to field surveys and can be applied to other regions and events.

Pour aller plus loin :

99 words

Radar Profile

The radar profile shows high scores in quantity and quality of information, with a moderate technical level. The reliability is high, but the lack of cited sources slightly reduces the overall score. The profile suggests a well-structured and informative presentation, suitable for a scientific audience.

Reliability 8/10