Automatic determination of shoreline at maximum retreating

Abstract

Coastal zones are the most influenced areas by global sea level rising. One of the important coastal zones in Egypt is the Red Sea. Red Sea coastal area is an attractive touristic area, which still under development. For the high value of such areas, the position of the set-back construction line is required for well planning and development. This position influenced greatly by the position of the shoreline at the maximum retreating. This paper introduces an automatic approach for determining the shoreline at the maximum retreating. This approach depends on three types of information; 1) the location of the current shoreline, 2) the mean higher high-water level (MHHWL), and 3) the topography of the coastal area.A study area North of Hurghada, is selected to apply the introduced approach. The shoreline is extracted out of Landsat-8 images based on a combination of three factors; a modified normal difference water index, the reflectance values of the water bodies in specific bands within the shortwave infra-red spectrum, and the relation of the reflectance values of water bodies in the Green, Red, NIR, and SWIR bands. The higher high-water level is determined from near tidal gauge station that has collected data each 30 min since 2008, and the topography of the coastal area is determined by the Kinematic GPS technique. The extracted shoreline was assessed by comparing it to actual shoreline traced on the ground. The results show that the accuracy of the extracted shoreline is within 15 m of the actual shoreline.