Accounting for Environmental and Anthropogenic Factors: Approaches to enhancing horizontal resolution and interpretability in geophysical surveys

Authors: Green and Holmes, R.

Common hindrances in geophysical survey, whether small-scale or landscape, are modern rubbish, rubble, ferrous objects, groundwater, and/or high attenuation materials. Groundwater and high attenuation materials greatly reduce the maximum potential depth of investigation. In an attempt to overcome these obstacles, surveys were conducted at the Dominican Friary in Trim, Ireland, which aimed to refine standard survey protocols for achieving high-resolution data from single channel ground-penetrating radar (GPR) surveys of small areas (<1ha). Based on the surveys’ results, it was determined that, for single channel GPR surveys utilising a central antenna frequency between 250MHz and 500MHz, a 0.1m traverse interval will maximise the potential to delineate targets smaller than 2.5m2, though for time efficient surveys, a traverse interval less than 25% the size of a discrete target (where the target is at least 1.5m2) provides adequate raw data to delineate significant anomalies. It is hoped that these parameters can also be applied to multichannel systems in due course.

Subsequent trials of these survey parameters were conducted at the TrĂ ng An Landscape Complex (Ninh Binh, Vietnam) as part of the SUNDASIA Project, where stratigraphic changes and discrete areas of anthropogenic activity in response to climate change were investigated. Applications of high resolution data acquisition methods proved successful within this environment, as GPR delineated discrete changes in high attenuation soil. Ultimately, these case studies demonstrate the success of small area surveys which face environmental challenges. Further analysis of the success rate of these parameters is to be expected at sites throughout southwest England and Ireland.

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