Coastal management strategy in Kourou, French Guiana

Stratégie de gestion du littoral de Kourou, Guyane française

François Longueville (1) , Robin Sigwald (2) , Laure Verneyre (1) , Grisel M. (2)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 Artelia Eau & Environnement [Echirolles]

for the 10th conference of the international society for integrated Disaster Risk Management French Guiana is an overseas department of France, part of the Guianas coast of South America. The Guianas coast is the world's longest muddy coast and one of the most active, due to the important sediment discharge from Amazon, which migrates alongshore as mud banks. Depending on the position of the mud banks, the coastline is more or less vulnerable to erosion and marine sub-mersion. In 2016, the city of Kourou has faced several severe sea-storms and damage mainly on public infrastructures. At that period, the shoreface of Kourou was in an 'inter-bank' phase (position between two mud banks), thus particularly vulnerable to coastal erosion by waves. Consequently, the Kourou city council decided to implement a strategy for the sustainable management of its coastline at short, mid and long-term. An innovative approach for French Guiana including three phases was conducted. The first step was to evaluate human, economic and environmental issues through field surveys of the population to qualify the typologies of habitats, to identify their perception of coastal risks and to address the different coastal uses. Secondly, we determined the coastal hazards (erosion and marine submersion) in a complex hydrosedimentary system at different timescale. Finally, management scenarios and their economic analyzes were compared and combined to provide decision keys for the town planning strategy. The results of public surveys showed that the population knows little about the sedimentary functioning of the beach and coastal evolution in general. However, the population would be ready to be relocated, if there are not viable technical solutions, conscious of the natural processes at stake. From several hypotheses and from a statistical analysis, the position of the coastline was projected by 2030 and 2050 and the marine submersion was carried out for a 30-year and 100-year return period. Considering the local dynamics, the modeling was done in the most unfavorable case of 'inter-bank' phase. The different scenarios were phased in the short, medium and long term. In the short term, the goal is to provide protection of the population from erosion, using cost effective and

Domaines: Géologie appliquée

François Longueville, Robin Sigwald, Laure Verneyre, Grisel M.. Coastal management strategy in Kourou, French Guiana. The 10th conference of the international society for Integrated Disaster Risk Management - IDRIM 2019, Oct 2019, Nice, France. . ⟨hal-02284478⟩