Evaluation of the efficacy of coastal defence structures in relation to coastline variations

Abstract

A process of evaluating the efficacy or inadequacy of coastal defence structures has been proposed through a study of littoral evolution inferred by analysis of coastline variations.

This study was undertaken in two parallel phases which have set the incorporation of cartographical and field measurement data in a geographical information system (GIS) package.

The GIS package provided for the establishment of the distinct layers based on the chronological order of events (layer of coastal relief and layer of the construction of the defence structure). This GIS application has made it possible to construct a dynamic archive of morphological–sedimentological information useful for determining the evolution of the littoral in the period following any defensive intervention and to evaluate its efficiency.

In addition, other than the usual query, it is possible to automatically calculate the areal variations of the littoral inferred from the coastlines and to consequently make a semiquantitative estimate of the sediment moved.

Keywords:

• Coastline
• Coastal defence structure
• GIS
• Coastal evolution