FORWARD MODELING OF SP RESPONSE OVER SINKHOLES IN COVERED KARST TERRAIN

Forward modeling of SP response over sinkholes in covered karst terrain

Numerous factors can contribute to self-potential (SP) anomalies over sinkholes in covered karst terrain. These include (a) groundwater flow through sinkholes that function as zones of connection between surficial and intermediate aquifers, (b) unsaturated zone flow that can serve as recharge following rainfall events or be lost as evapotranspiration, and (c) variations in streaming potential coupling coefficients at lithologic boundaries, particularly in association with the clay layer that forms as a weathering horizon on the top of limestone. Here we attempt to understand the potential relative significance of these various factors as contributors to SP signals over sinkholes. To do this a suite of forward models are run using the Comsol finite elements modeling package, following recent developments in the theoretical understanding of SP signals.