Ground-penetrating radar investigation of preferential flowpaths on a hillslope

Abstract

A hillslope investigation took place for the purpose of confirming correlation between ground-penetrating radar returns and stormflow. A sprinkler system was operated over a 280 by 200 cm area of the slope in order to generate subsurface flow. Through previous investigations a kinematic response had been shown to rapidly mobilize high rates of runoff. It had been found that a threshold condition occurred near saturation which activated the kinematic pressure wave. For our experiment this process drove delivery through preferential flowpaths into a runoff gutter collection system. Temperature changes and rainfall rates were monitored as well as volumetric rates of response. Radar returns were processed and examined afterward. A separate soil core experiment was also conducted under laboratory conditions. This was done to characterize the retentivity of the soil since antecedent soil moisture makes up the majority of the water that becomes mobilized. Comparisons between hydrological and radar data were made utilizing the gathered information.