항공원격탐사자료를 이용한 갯벌 표층 퇴적상 매핑

Abstract

Tidal channel networks have been considered as an important key in the evolution of tidal flats, thus manystudies have tried to reveal the geometry of tidal channels and their relations with surface sediment distributionin the tidal flat (Fagherazzi et al., 2008). Recently, airborne remote sensing with a high spatial resolution hasbeen applied to the tidal surface sediment classification (Mason et al., 2006). It has a great advantage in that wecan identify the spectral and textural differences which are represented in the image, thus an achievement ofmore accurate mapping is possible. In this study, mapping of the surface sediment distribution in a tidal flat wascarried out based on field observations and an adjustment of the map using an aerial photo image was attempted.Tidal channel networks were extracted from the aerial photograph and its spatial relations with the sedimentaryfacies were estimated for the adjustment. Test was carried out in Geunso Bay, Korea, which is characterized by70 % of its tidal flat being exposed at ebb tide and the shallow water depth of about 2 - 4 m at flood tide. Fortyfivesediment samples were obtained by a shipboard grab sampler at flood tide on February, 2009. The sampleswere classified into three types of facies according to the percentages of grains that are larger than very fine sand(0.0625 mm) after Folk (1968); sand flat (above 70%), mixed flat (30 - 70 %), and mud flat (0 - 30 %). These insitu data were used to generate a sediment distribution map using a krigging method. Tidal channels were extractedfrom an aerial photo image with 50 cm resolution which was acquired on February, 2008, and the spatial relationshipof the tidal channels with the surface sediments was estimated using a fractal and GIS analysis. Thespecific spatial characteristics of tidal channel networks for each sedimentary facies were identified, based uponwhich the interpolated map of sediment distribution was adjusted. Mixed