EVALUATION OF ALOS-2/PALSAR-2 DATA FOR BEACH SHORELINE DETECTION

摘要

Previously defined editorial technique for topographical map and monitoring regional coastline have been commonly depended on airborne surveillance. Since late 1970s, optical remotely sensed imagery derived from various satellites has been widely utilized. However, ALOS-2/PALSAR-2 is more useful than optical imagery insofar as it is capable of observing day and night, and in all weather conditions. In this study, the authors looked at evaluation data observed at various off-nadir angles and satellite pass designations (Ascending or Descending) for sandy beach shoreline detection. As our study area, sandy beach on the Kujukuri Coast, Chiba Prefecture, east Japan was selected. The Kujukuri Coast is an approximately 60 km long stretch of uninterrupted sandy beach on the Pacific Coast of northeast Chiba Prefecture. Eight different types of PALSAR-2 off-nadir angles including different polarization modes (single, dual, and quad) were analyzed. As a result of this study, we gained knowledge about detecting a sandy beach shoreline from suitableness PALSAR-2 data. The PALSAR-2 observed with below 30??off-nadir angle and SAR beam facing the opposite direction of landward wave seems to provide appropriate images to detect shoreline. In conclusion, observational conditions of the PALSAR-2 image has a measurable influence on interpreting a sandy beach shoreline.