AnIntegrated Study of ShorelineVariability Using Gis andARGUSTechniques
Abstract
GIS techniques (Arcview) were used to study the long term (last 20 years) shoreline variation in the area of Lido di Dante, Ravenna, northern Italy. The shoreline was identified on the photos as the High Water Line on 4 flights (1978, 1982, 1996, 1998). Evaluation of the error associated to the method (tidal range) indicates an horizontal variability of HWL in the order of 10-30 m, according to the beach slope typical of the different parts of the beach. This means that GIS techniques can be only used as a qualitative instrument for long-term assessments, as on short periods the
noise can be high. In any case, the coastline can be broadly described by two segments: one in erosion affected by the presence of structures and one quite stable, dominated by natural process. To assess the correctness of the data extracted from the GIS, topographic surveys were carried out with a GPS in kinematic relative positioning and a total station. These surveys revealed that the area is eroding in the northern part, is oscillating in the central part and is in oscillation/accretion in the southern one. An ARGUS station was installed in the area. Short-term (hours) shoreline surveys were carried out to compare the GPS data with the ARGUS ones after putting them in a GIS. This comparison revealed that the ARGUS and GPS shorelines are identified with a precision which is comparable