STUDY OF COASTAL MONITORING INDICATORS FROM PLEIADES-LIKE DATA: DETECTION OF BOATS MOORING AREAS AND COASTLINE MONITORING

摘要

Pleiades was launched in December 2011 and is offering high spatial resolution images that could support a number of thematic studies for environmental monitoring. In the present communication, we investigate the specific case of the coastal zone monitoring. As per number of areas, environmental studies of the coastal zones are dedicated to the analysis and quantification of pressures that might alter the quality of the environment as well as the characterization of the vulnerability of coastal sites (expressed in terms of biodiversity and fragility of the ecosystem). The anthropic pressure applied on coastal site is either due to recurrent activities (e.g sewage plants and release of waste waters, defense infrastructures) or seasonal activities (recreational shipping, beach frequentation). With respect to new or emerging environmental regulation at regional and European level (e.g. Marine Strategy Framework Directive and EU Water Framework Directive) several objects of interest are requested to be monitored in order to build up environmental indicators. In the following we describe two indicators that could be derived from Pleiades products. The first one is the level of deterioration of the coastline i.e. the number and the types of manmade infrastructure at coast. Surprisingly enough, this information is not always known by local authorities and if known is the most often not up-to-date. Besides the requested knowledge of the infrastructure for the benefit of coastal planning, detection of manmade (or at least non natural) features at coast is also the way to detect illegal or not well known potential discharge of industry residual at sea. This is the case for countries where environment is suffering of weak regulation and thus is not well monitored. Pleiades could be the way to detect typical features at coast that might represent undeclared pollution release. The second element, which is also synonym of anthropic pressure, is the level of uncontrolled ship moorings during summer period. Far from being marginal, this represents a real pressure on the seafloor habitat and flora which suffer from mooring systems. High spatial resolution products have been used (similar as the one from Pleiades) to do the survey of these areas and get a reliable estimate and zoning of this pressure.