Le suivi environnemental du dragage de Vavouto (Nouvelle-Calédonie). Un chantier de dimension mondiale à la porte d'un site classé au patrimoine mondial

Abstract

In the northern part of New-Caledonia, the installation of a factory dedicated to the nickel ore processing requires to dredge a navigation channel of 4500 m long with 7300000 m of extracted materials. The dredging process has taken place very near of sites inscribed recently in the world heritage list of UNESCO because of the exceptional biodiversity of their reefs and associated ecosystems. First, this paper introduces the framework of the environmental supervision which includes a real-time monitoring of the physico-chemical parameters of the water and the sediments, as well as an important assessment system of biological observations. The measurements relative to the monitoring of turbidity are detailed and analysed. Then, the results of the environmental monitoring and the interest of the chosen approach are explained. Especially, an environmental committee of Koniambo (named CEK) has been set up in order to assure that all the monitoring observations are communicated to the local populations. This action is a crucial stake for the country. The factory can contribute to the economic rebalancing between northern and southern parts of the island as registered in previous nationwide agreements, but this should be done in the respect of the fragile environment and the societal practices of the populations which live in the impacted zone. The last section deals with the interest of the use of interoperable data bases for the environmental management. Some hints are proposed about analysis methods, modelling and information flow of the environmental monitoring within this sensitive context. They are meant to facilitate the communication between operators, technicians, engineers and consultants. The proposed methods make also easier the check of the procedures and the analysis of the data by the experts in charge of the monitoring. Key-words: Dredging process – Turbidity – Environmental supervision – New Caledonia – Reef ecosystem – Interoperable database – Sustainable development