Sinkhole structure imaging in covered Karst terrain

• Published in: Geophysical research letters Vol. 33; no. 16; pp. L16405 - n/a
• Main Authors: Kruse, S., Grasmueck, M., Weiss, M., Viggiano, D.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.08.2006; Blackwell Publishing Ltd
• Subjects: Earth sciences; Earth, ocean, space; Electromagnetics; Exact sciences and technology; Hydrogeophysics; Hydrology; Instruments and techniques; monitoring; Central Florida; Florida; United States; Spain, Guipuzcoa, Pyrenees Mts., Central Depression; USA, Florida; maps; terrains; Resistivity; ground water; surveys; sinkholes; indicators; karst; North America; ground-penetrating radar; depressions; aquifers; three-dimensional models; Mapping manifolds; two-dimensional models; Diameter
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2006GL026975

Ground penetrating radar (GPR) and resistivity techniques have been widely used to map the locations of sinkholes in covered karst terrain. To determine whether a sinkhole is a likely preferential conduit for groundwater flow, however, requires higher‐resolution imaging than that used in conventional sinkhole mapping surveys. Field observations combined with simulated surveys for a 15‐m diameter 3‐m deep sinkhole in west‐central Florida are used to assess the resolution of GPR and resistivity surveys targeting the semiconfining unit that floors the sinkhole depression. 2D resistivity surveys clearly show the central depression as well as resistivity contrasts between the cover sediments within and outside of the sinkhole, but are inadequate for resolving breaches in the semiconfining unit or underlying conduits. A 3D GPR survey resolves vertical structure on the order of tens of centimeters within the semiconfining unit, as well as indicators of conduits that extend several meters beneath the central depression. 3D GPR thus holds promise for imaging hydrologically significant features of sinkholes.