Rapid assessment of geo-hydrological hazards in Antananarivo (Madagascar) historical centre for damage prevention

Abstract

The historical centre of Antananarivo represents one of the most important cultural heritage sites in Madagascar. During 2015, the whole city area was severely affected by geo-hydrological hazards due to cyclonic rain, resulting in severe flooding, and in widespread shallow landslides along the hillslopes. This event proved the vulnerability to geo-hydrological risk of the Upper town’s historical buildings. In October 2017, a geo-hydrological hazard mapping was performed in the Upper Town by combining field surveys, remote sensing and geomatic data analysis in a GIS environment. This provided detailed products such as a geological-geomorphological map, a map of the hydrographic network and of the creek basins, and a geodatabase to be used for detecting areas prone to erosion and geo-hydrological hazards. The final aim was to understand the geological, geomorphological and hydrographic features of the Upper Town, in order locate the more critical areas and to recommend priority works to be carried out, as a first step toward a risk management strategy and a conservation/valorization plan for building the resilience of the site. The results highlighted that a Cultural Heritage site protection strategy can be planned also in case of limited data, which is a frequent condition in developing countries.

Keywords:

• Soil erosion
• cultural heritage
• geo-hydrological hazard
• field survey
• Antananarivo

Acknowledgements

This work was carried out in the framework the activities of the UNESCO chair on prevention and sustainable management of geo-hydrological hazards (University of Florence, Italy). The authors would like to thank: IMV Tana City lab and in particular Tamara Teissèdre-Philip and Alexandrine Wadel for providing all of the available topographic data, orthophoto, historical pictures and especially kindness and support during our work; François Cristofoli (RC Heritage/RCh consultants) for the logistic support and precious suggestions; Helihanta Rajaonarison of Antananrivo University for her precious knowledge and guidance, Niandr and Zahara for their valuable assistance and enthusiasm.

Disclosure statement

No potential conflict of interest was reported by the authors.

Websites

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www.eumetsat.int

http://www.bngrc.mg

https://www.americangeosciences.org/