Coastal monitoring using remote sensing and geoinformation systems: Estimation of erosion and accretion rates along Gaza coastline

Gaza coastal zone is under great pressure from both the human activates and the marine processes, for instance, marine currents, waves, tides, surface circulations. The objective of this study was to use remote sensing and geoinformation systems (GIS) to monitor and analyze the coastline dynamics during the last two decades. In addition, the effect of Gaza seaport on the reshaping of the coastal zone was evaluated. The study was performed using three different sets of images: Landsat ETM images, Landsat TM-5 and SPOT-5. Based on this, it was examined whether it would be possible to get a reasonable result from medium resolution imagery. The images were geometrically corrected and registered with RMS vary from 0.015-0.2 pixel. Atmospheric correction was performed using FLAASH Model. ETM Landsat images (30m) were pan-sharpened using A´trous Wavelet Transformation in order to improve the spatial quality. PCA, Tasseled Cap Transformation, Band Ratio and NDVI were used in order to automatically extract the coastline. The accuracy assessment was performed between the these different methods using manually digitized coastlines. The coastline were then automatically extracted from all images. The rate of change was calculated between 19986 and 2008. The results indicate a negative rate in general. The southern side of Gaza seaport obtains a positive rate and accretion in the beach area. This positive rate is due to the accumulation of the sediments on the southern side of the seaport.