Ground Penetrating Radar

GPR is extremely useful for obtaining a non-invasive image of the shallow sub-surface particularly when detailed positioning of artifacts is the objective. Responding to variations of electrical properties (dialectric constant) GPR measures radar impulses which are triggered by variations of rock properties or the introduction of a foreign object within a homogeneous medium. The stronger the reflection, the greater the difference in the dialectric constant. GPR uses high frequency radio-waves in the range of 10MHz to 2.6GHz. An electromagnetic energy wave is transmitted into sub-surface materials and reflected/refracted and scattered differently, depending on the material’s permittivity.

Ground penetrating radar is a technique capable of mapping interfaces in a cross-sectional format. Typically, radar reflections occur with abrupt changes in moisture content, grain size, porosity, or soil texture. It is a cost-effective, high-resolution method to fully define soil stratigraphy, bedrock interfaces, fracture zones and groundwater surfaces. GPR can be used to study underwater depth, estimate water volumes and reveal sub-bottom stratigraphy. It is the most suitable method to use under frozen conditions. In addition, GPR surveys are often used to locate objects such as buried tanks, fibreglass or plastic lines, and utility corridors. It is also used for forensic and archeology applications to locate buried structures and features.