Inland and Coastal Hydrographic Feature Identification in the Bahamas Using RADAR Data and Raster Processing in a GIS

Islands within the Caribbean region are frequented by heavy rains and strong winds, causing flooding and damage to infrastructure and the environment. The increasing availability of spaceborne RADAR data offers advantages over optical imagery for the mapping and mitigation of such hazards. RADAR data has the ability to penetrate cloud cover, making it capable of collecting data during virtually all weather conditions. In this study, the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture RADAR (PALSAR) was used to distinguish seasonally dynamic water bodies on New Providence Island in the Bahamas using an image thresholding technique. The threshold was determined by performing statistics on field-validated training sites. The accuracy of the RADAR data’s classification of water bodies was tested using a control dataset derived from GeoEye-1 imagery and GPS points collected during field work. The RADAR data was found to best classify large, static water bodies. It less accurately classified small, seasonally inundated water bodies and small ponds that are not spatially separated from vegetation. This study demonstrates a practical methodology which can be easily adapted by government and emergency management agencies within the Caribbean, as a preparation and mitigation tool. As such, it addresses the need for accessible data, techniques, and methods, designed to improve the understanding of dynamic natural phenomenon and assist government managers with decision making.