Study of the beach zone of Koutsounari (SE Crete) using video monitoring methods = Μελέτη της παραλιακής ζώνης του Κουτσουναρίου (ΝΑ Κρήτη) με τη χρήση οπτικών μεθόδων παρακολούθησης

Περίληψη

Coastal zones are among the most active areas on Earth, changing their shape from day to day, or even from hour to hour. The present study investigates the application of video monitoring methods for mapping the beach evolution and the shoreline changes of the microtidal Koutsounari beach in SE Crete. A videobased coastal imaging system consisting of two cameras, installed on the upper beach at an elevation of 14 m above MSL, was used to monitor the study area from 26 November 2012 to 26 May 2013, acquiring images at a rate of 4 Hz for 10 min every hour of daylight. The extraction of the successive shoreline positions was based on 1363 variance images (SIGMA) using specially developed software. Analysis of the recorded shoreline displacements showed that during most of the time the whole length of the shoreline responds in unison (either advancing or retreating) to changes in hydrodynamic conditions. During storms the shoreline retreats, as erosional processes prevail, but recovery is rapid (within 24 h) after the storms. Four shoreline rotation events were recorded, associated with ESE-SSE and SSW incoming waves, which induced increased longshore transport rates. The highest recorded wave run-up was 1.0 m. The eastern part of the beach is more vulnerable to the prevailing wave direction (ESE-SSE) and significant wave heights than the western part.