SURVEYING PERCHED WATER ON ANTHROPOGENIC SOILS USING NON-INTRUSIVE IMAGERY

Wetland soils of anthropogenic origin are difficult to map using conventional soil surveying methods. While traditional soil profile classifications are highly accurate at the borehole, beyond the sampling point the soil-unit boundaries must be visually extrapolated from the surrounding natural terrain. Anthropogenic soils are often erratic, many possessing unpredictable morphologies. Mapping precision is limited by additional sampling expense and site restrictions to excessive borings. In order to increase mapping precision, this project compared measurements of shallow water table depth in copper-mine tailings as determined by (1) intensive conventional soil morphology classification, (2) ground-penetrating radar (GPR), and (3) electromagnetic induction (EMI). Ground-penetrating radar and EMI results were in agreement with water table depths as determined by soil morphology. Wherever a well-formed densic contact was present, GPR and EMI interpretations of water table depths when used alone were inconclusive. The combined technologies, employed in tandem, detected the densic contact layer. Non-intrusive technologies improved mapping precision when combined and supplemented with conventional soil mapping techniques.