SIMULATING SOLUTE TRANSPORT WITHIN KARST USING THE CONDUIT FLOW PROCESS FOR MODFLOW-2005

Karst aquifers differ from porous media as they exhibit channeled preferential flow paths, and rapid hydraulic responses with laminar and non-laminar groundwater flow. The Conduit Flow Process (CFP) was developed to simulate non-laminar groundwater flow within karst environments. CFP Mode 1 simulates karst aquifers as a pipe network, and transport may be estimated using pipe residence-time calculations. CFP Mode 2 simulates non-laminar flow within preferential flow layers. Combined application of CFP Mode 2 with existing MODFLOW solute-transport simulators may be useful for simulating both advective and dispersive solute transport within karst preferential flow layers. Technical limitations include (1) additional programming required to increase CFP transport compatibility with other MODFLOW packages and processes, and (2) incorporating spatial variability in non-laminar flow model parameters such as mean void diameters and critical Reynolds numbers. Removing these limitations could create a straightforward and versatile tool for simulating non-laminar flow and transport within karst environments.