Environmental impact identification along the Corsican coast (Mediterranean sea) using image processing

Endowed with an exceptionally rich natural heritage, the Mediterranean isla nds are subject to degradation exacerbated by their insularity (e.g. the in flux of tourists in the summer). The management of these coastal areas thus requires the identification and quantification of anthropogenic impacts wh ich affect the distribution of seagrass beds. To this end, studies were car ried out along the Corsican coast by combining image processing of (i) aeri al photographs for the surface layer (from 0 to -20 m) and (ii) sonograms, generated by side scan sonar, for the deeper layers (from -20 to -40 m). Th ese techniques, which are particularly adapted to the analysis of vast area s with a precision of less than 2 m, were used to identify and accurately e valuate the impact of natural and anthropogenic pressures (e.g. fresh water input, coastal facilities, mechanical aggressions). In addition to a decli ne in the surface area occupied by seagrass beds, significant erosion of th e coastline (80 m in 25 yr) was observed, brought about by the building of marinas. Based on the results generated in the present study, it would appe ar that these techniques may prove useful in the examination of other coast al regions. (C) 1999 Elsevier Science B.V. All rights reserved.