The reconstruction a portion of the geomorphic past of Gamay Bay’s coastal plain in Northeast Samar, Philippines advances the understanding of past depositional and erosional events. Three separate sites in Gamay Bay were analyzed with ground penetrating radar (GPR). This study focalized on site two which displayed fluvial patterns. GPR reveals subsurface reflections interpreted as sediment layering. It sends electromagnetic (EM) radio wave pulses into the earth’s surface displaying subsurface images. GPR surveys were collected using a Sensors and Software® pulseEKKO GPR Pro with 100 MHz antennae. The transmitter and receiver antennae were placed 1m apart sending EM pulses at 0.25m intervals along a 400m transect. EM velocities calculated from GPR data ranged from 0.08-0.1m/ns which indicated moist sands. GPR data revealed a series of channel-like reflection patterns. Sediment cores reaching about 1m in depth were analyzed at areas noted from GPR data. Core analyses described subangular and well sorted sediments, a common indicator of a fluvial deposit. GPR and sediment core data in tandem provided support for the hypothesis that site two was a fluvial environment. The integration of GPR and sediment coring were successfully used in the identification of a buried fluvial channel system within Gamay Bay.
