Hydrography and geomorphology of Antananarivo High City (Madagascar)

William Frodella,Daniele Spizzichino,Andrea Ciampalini,Claudio Margottini,Nicola Casagli

doi:10.1080/17445647.2020.1721343

Abstract

ABSTRACT The city of Antananarivo is located in the central highlands of Madagascar, and is the largest urban center of the island. Considering the frequent heavy cyclonic rains frequently affecting the area, its geomorphological context is particularly prone to geo-hydrological hazards, such as landslides and flash floods, as recently proved during the disastrous events of the winters of 2015 and 2018. Field data and high-resolution remote sensing data interpretation (DEMs and satellite orthophotos) were combined in order to produce detailed hydrographic and geomorphological maps. The aim was to understand the processes acting in the Analamanga hill area, with special regards to the effect of human activity in modeling the natural landforms and exacerbating the geo-hydrological hazards. The obtained maps will provide management-planning tools to be used as a first step towards a risk reduction strategy in the Antananarivo historical urban center.

Highlights

Antananarivo is the capital city of Madagascar and is located in the central highlands region (18.55′ South; 47.32′ East), about 160 km from the east coast and 330 km from the west coast, at approximately 1200 m a.s.l. above sea level (Figure 1)
The identification of landslide processes on the field was not an easy task, due to the rapid modification of the landforms and slope cover caused by the intense hovel urbanization
The combination of field surveys and the interpretation of remote sensing data has provided the detection of landslide processes and of the hydrographic network with a satisfactory resolution from the local to a large scale

Summary

Introduction

Antananarivo is the capital city of Madagascar and is located in the central highlands region (18.55′ South; 47.32′ East), about 160 km from the east coast and 330 km from the west coast, at approximately 1200 m a.s.l. above sea level (Figure 1). The High City represents an important cultural heritage site of Madagascar, encompassing the new stone brick-built Rova and Chapel, the high dignitaries’ buildings, such as the baroque-style architecture Andafiavaratra palace, the Cathedrals of Andohalo and Ambohipotsy, built by the first missionaries in the second half of nineteenth century (Figure 3). The rapid urban development of Antananarivo, together with the lack of a proper urban planning, due to political and governance issues, have caused several environmental problems, such as intense

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Conclusion