One year wetland survey investigations from quad-pol RADARSAT-2 time-series SAR images

Remotely sensed data are widely used to identify, delineate, and characterize wetlands. Optical data provide interesting information to inventory vegetation and agricultural practices in wetlands but are limited to cloud-free periods. For this reason it is not possible to precisely delineate the extent of saturated areas as well as water cycles and water levels in these areas with passive remote sensing techniques. The objective of this article is to evaluate fully polarimetric RADARSAT-2 time-series datasets to identify and locate the seasonal dynamics of saturated areas in wetlands. To that end, the development and validation of a supervised PolSAR segmentation including multitemporal analysis of wetland evolution and polarimetric decomposition method is presented. The proposed methodology is based on the segmentation of a polarimetric descriptor, the Shannon Entropy, which has been shown to be a very sensitive parameter to the temporal variability of flooded areas. The results were validated using ground truth measurements in the field and a LiDAR image. They showed that it is possible to produce detailed water feature maps useful for delineating and monitoring the seasonal dynamics of saturated areas extent in wetlands. These products provide useful information to identify and delineate wetlands to support conservation and management in these ecosystems across large areas.