Control factors of spectral reflectance in tidal flat: a case study in the Gomso Bay, Korea

The objective of this study is to investigate the control factors of spectral reflectance and microwave scattering in tidal flat. The control factors are generally considered as grain size, soil moisture content, local slope, and creeks. We have carried out field data sampling in the Gomso Bay, Korea, including grain size, soil moisture content and its variation with time, surface roughness, ground levelling, and field spectral reflectance measurement. We have analyzed Landsat TM, EOS-Terra ASTER, RADARSAT, ERS-1/2, and JERS-1 SAR data. L- and C-band radar scattering modelling was also conducted. The results show that tidal condition and remnant surface water are important additional parameters. SWIR is shown to be correlated most with sediment grain size. The grain size of 0.0625 mm has normally been considered as a critical size of mud and sand discrimination. But we propose here that 0.25 mm is more practical grain size criterion in optic remote sensing. The radar scattering modelling show variation of less than 15 dB within the tidal flat, and L-band HV-polarization is turned out to be the best for tidal flat observation. The SAR data is also sensitive to the effective exposed area (EEA) effect.