NONINTRUSIVE MAPPING OF NEAR-SURFACE PREFERENTIAL FLOW

A unique survey protocol has been developed that maps near-subsurface preferential flow using integrated ground-penetrating radar (GPR) and a differential geographical positioning system (DGPS). The survey protocol consists of a mobile GPR system that spirals outward along a prescribed course, continuously gathering subsurface data for an extended period. Metered water is applied to a centrally located water-ponding ring, after first capturing the initial dry-state pattern signatures. The water radiates outward beneath the surface as it follows preferential flow pathways, which the GPR instrumentation spiraling above highlights. After data are collected, pre- and post-water time-elapsed images profiles are segmented by pattern dissimilarities. The specific locales that exhibit pattern shifts from the initial dry state are identified as dynamic water movement. Locales that exhibit pattern shifts are mapped to indicate the rate and direction of preferential flow about the near surface.