Estimating coastal vulnerability in a meso-tidal beach by means of quantitative and semi-quantitative methodologies

Abstract

The main goal of this study is to estimate the coastal vulnerability on a stretch of coastline by using two different methodologies and to check if both methodologies give rise to similar results or if notably dissimilar assessments are obtained. To reach the above mentioned objective, a new experimental methodology (Benassai et al, 2009) based on inundation of the inshore land and the well known USGS methodology (Gornitz et al, 1994) are applied and compared. In the first approach, a new parameter, named as impact index, is calculated by using wave climate and geomorphologic data. In general, impact index depends on run-up height, seasonal and long term erosion index and the efficiency of existing structures for coastal defence. The relative value of this parameter is contrasted with that of the often used coastal vulnerability index, CVI, which includes geological and physical variables. The application of these methods gives rise to significantly different levels of vulnerability for the same zone. This situation must be attributed mainly to the distinctive nature of the used methods. Thus, taking into account the results, it is remarked that the procedure to choose a methodology for assessing the vulnerability of a given coastal zone must be based on the available information and on the characteristics of the zone. Furthermore, the use of the same method to do risk and vulnerability comparisons is recommended.