Abstract:

The land cover around in the Tonle Sap floodplain, Cambodia is strongly influenced by varying water levels. The lacustrine landforms and vegetated areas are partly inundated due to increases in the water level. Conversely, they are gradually emerged when the flooding recedes during the dry season. The backscattering coefficients of ALOS PALSAR data can be used to monitor the landcover variation for all weather condition during flooding period. Therefore, a backscattering coefficients variation model with respect to water level was constructed in the annual flooding. In this model, the backscattering coefficients corresponding six landcover classes depics the effects of flooding using interaction between radar signals and land cover classes at different times in the annual flood pulse. The HH and HV polarization of radar signal also permits to improve the distinction between the statuses of landcover classes due to flooding effect. With a backscattering coefficient change from -8.4 dB to -20.6 dB for lowland shrubs in the flood developing stage, the model result corresponded to a water level change from 3.83m to 8.06 m.