SHORELINE TEMPORAL VARIATION OF WAVE DOMINATED SANDY BEACHES OF THE SOUTHEAST OF SANTA CATARINA ISLAND (FLORIANOPOLIS, SC, BRAZIL)

Abstract

Shoreline variation occurs at several temporal scales and the most useful time span for human context is about 100 years or less. At the Santa Catarina Island, environmental problems related to unplanned human occupation and activities resulted in coastal erosion and lost of environmental quality. This study is about a shoreline variation analysis at inter decadal scale, and inter annual scale involving 64 and 4 years time span evaluation, respectively, to five sandy beaches located at southeast of Santa Catarina Island. The data source was composed by 5 time series of aerial photographs, which was digitized, and managed by geoprocessing techniques, using digital cartography and Geographical Information System tools. The general trend of shoreline variation showed an erosional rate a little bit more than half meter per year, and an average shore retraction less than fifth meters in 64 years. At the interannual scale, rates and beach width was lesser than inter decadal, yet, the ranges at some specific beach location reached rates four times superior. However, not even all beaches showed erosional trend in one or both time spans analyzed. The shoreline variation among both time spans allowed the smoothing coastal processes of short periods making possible to highlight trends in higher temporal horizon. This approach let to explore shoreline variation by the distinct ways of interesting of coastal planning and management.