| Remote sensing and advanced digital image processing techniques were developed and tested for delineating karst features important for the subterranean hydrology in the Tanama River and Rio Grande de Arecibo catchments located in the North Coast Tertiary Basin of Puerto Rico, where groundwater contributes to base flow for surface water bodies which in itself is the main supply of drinking water. This aquifer region is a karst platform of carbonate rocks and clastic beds, thought to comprise a confined aquifer beneath and an unconfined aquifer. Products derived from ASTER, Landsat (ETM+ and TM), a NED DEM (30 m), and a LiDAR DEM (2 m) were analyzed in the interpretations of the karst flow system. In addition, field verification, VLF-EM, and previously published hydrologic data were analyzed to characterize fracturing and dissolution features on groundwater hydrology in the region. Remote sensing assessments show that Landsat PCA (incorporating thermal band), ASTER PCA, LiDAR Hillshade were best at detecting "true" lineaments in this type of terrain. NDMI proved to be helpful in detecting moisture changes attributed to lineaments influencing the shallow hydrology in the karst. Geomorphic data agrees with lineaments as faulting and fracturing in addition to linear bedding control features. Sinkholes, springs and geotectonic evidence locations occur along and at the end of lineaments. Lineaments interpreted from LiDAR DEM data (Aspect, Hillshade) show regional geomorphotectonic evidence correlated to sharp river bends, hill alignment, and aspect trends. |
