ABSTRACT: Integrating GPR, GPS and GIS to build subsurface terrain models and constrain hydrological models.

CGRG Bibliography of Canadian Geomorphology
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Abstract

We developed the GPR Construction Kit (GCK) to allow easy integration of Ground-Penetrating Radar (GPR) data with Global Positioning System (GPS) data and export to Geographic Information Systems (GIS). The prototype system provides basic tools for project management, data integration, and feature identification. It provides simple analysis tools to accurately position identified features in three dimensions, even in complex and heterogeneous subsurface environments. GCK is designed to follow an iterative, interactive workflow. First, GPR and GPS data files are assigned to a project. Second, the ground surface position of each individual GPR trace is automatically located in 3 dimensions using logged GPS data (accurate to 1cm with a survey-grade receiver). Clusters of GPS readings are assigned to each GPR trace and aggregated or interpolated based on a time-stamp matching algorithm, followed by manual editing as desired. Time-consuming conventional survey layouts may often be avoided, saving time and opening the possibility of surveys in more difficult environments. ESRI shapefiles may be generated for each section or trace, containing all sample data. Synthetic sections may be constructed from selected traces. Third, boundaries between layers of homogeneous subsurface material can be digitized and labelled, with a propagation velocity for each layer. All layers and boundaries are topologically linked dynamically. Fourth, the the GPR’s time domain is converted to a linear depth below surface using multiple propagation velocities. These steps may be revisited in any order and as many times as desired to refine the subsurface model. Finally, once the subsurface model has been developed to a satisfactory degree, a layer boundary can be selected by name (e.g. 'water table'). All digitized lines with the same name are collected from all sections, and their locations and attributes exported into a shapefile for use in GIS or other subsurface modelling software. The GCK software and workflow will be demonstrated via several case studies.

Bibliography of Canadian Geomorphology