TerraSAR-X을 이용한 동검도 갯벌 주변의 염생식물 모니터링

Abstract

Salt marsh is generally classified into high and low marshes according to exposure time. High marsh is located in high tidal area affected by land and continuously exposed more than 10 days in a month. Low marsh is inundated more than 360 days annually. Halophyte such as Suaeda Japonica, Phragmites Communis are widely spread around Donggum-do tidal flat. They can be an environmental proxy to study landization or succession of tidal flats. As demineralization of tidal flat proceeds, the colony of halophyte moves seawards where salinity content is relatively high. As morphology of tidal flat is changed, the location and dimension of halophyte patch and their primary species are altered. Precisely locating halophyte patch and identifying dominant species are important to understand the status of tidal flats. Although halophyte has their spectral peak, it is difficult to identify in multispectral images mainly because of relatively low spectral or spatial resolution. TerraSAR-X data are investigated in this study with ANOVA analysis. The relationships between the backscatter coefficient and halophyte/sediment were examined. Significant variations were found within sediment due to the varying saturation and moisture content throughout all images. HH-HV backscatter was better correlated with halophyte than VV-VH mode. Halophyte patch traced in TerraSAR-X image in 2008 were slightly different from lines observed by field trip in 2009. Disagreement of the traced lines could result from temporal difference because most examined halophyte is annual plants. According to sea level change in the tidal flat, the location of halophyte patch can be changed. Although we are not able to verify the accuracy of traced lines from TerraSAR-X image in 2009 due to the lack of dual mode, the results show that halophyte patch can be effectively identified by dual-polarization TerraSAR-X images.