ANALYZING SHORT-TERM SHORELINE CHANGES ALONG THE EBRO DELTA (SPAIN) USING AERIAL PHOTOGRAPHS

The use of aerial photographs to estimate short-term shoreline changes , i.e. coastal changes at a monthly scale reflecting seasonal changes in the underlying hydrodynamics, is presented in this paper. To achiev e this a data set of seven vertical aerial photographs with a time spa n of four months, taken at the Ebro delta (NE Spanish Mediterranean co ast) has been used. The method was applied to the: analysis of very fl at areas, highly dynamic coastal features, storm impacts and to the en tire deltaic coast. Although the study area is a microtidal environmen t, obtained results of the very fiat areas analysis do not recommend i ts use at very short time scales due to meteorological tide influences . The formation, erosion and re-formation of a spit at the river mouth was easily monitored being controlled the evolution of its length, pe rimeter and subaerial surface. Aerial photos permitted to identify vul nerable zones to impacts of very energetic storms by characterising br eaching events along the coast (location and magnitude). Finally, when the method was applied to the entire deltaic coast, a detailed season al and spatial distribution of shoreline changes was obtained. The com parison of shoreline rates of change obtained from photos with that ob tained from beach profiles shows that the method is reasonably accurat e at least for the Ebro delta coast.