|Abstract||This study investigated the effect of the RADARSAT-1 incidence angle on the discrimination of the wetlands, including open bog, treed bog, and marsh, in the Mer Bleue bog conservation area in Ontario,
Canada. The results demonstrated that RADARSAT-1 can penetrate tall herbaceous vegetation in marsh at all incidence angles and short shrub vegetation in open bog with standing water at low incidence angles only, which reveals that RADARSAT-1
backscatter double bounce from open wetlands (marsh and bog) with standing water is related to the vegetation types. The analysis of the RADARSAT-1 synthetic aperture radar (SAR) backscatter of wetland and non-wetland land cover types confirmed that
the backscatter return of each land cover type decreases as the incidence angle increases. It was also found that the separations of marsh, treed bog, and open bog without standing water do not vary significantly with increasing incidence angles.
However, the incidence angle does affect the discrimination of open bog with standing water. The results from separability measures of land cover classes demonstrate that the combination of a low incidence angle (<31°) RADARSAT-1 standard beam mode
image with Landsat-7 data can provide good separation for all class pairs in the study area. The combination of RADARSAT-1 standard beam mode 1 (S1) and Landsat-7 images gave better classification results than the combination of RADARSAT-1 standard
beam mode 5 (S5) and Landsat-7 images: the classification accuracies (kappa indices) of various wetlands increased in the range 0.02-0.13. For optimal spatial detail, fine beam mode data are desirable because of the higher spatial resolution (-9 m).
However, in terms of the discrimination and classification accuracy of wetlands, fine beam mode data are not suggested because of the high incidence angle. Therefore, it is concluded that a lower incidence angle RADARSAT-1 image (e.g., S1) is the
optimal beam mode when combining with Landsat images for the discrimination and classification of wetlands. |