PATHWAY CONNECTIVITY IN AN EPIGENETIC FLUVIOKARST SYSTEM: INSIGHT FROM A NUMERICAL MODELLING STUDY IN KENTUCKY USA

• Main Author: Adams, Ethan
• Format: Others
• Published: UKnowledge 2019
• Subjects: karst SWAT; combined discrete-continuum; karst hydrology; swallet; estevelle; Civil Engineering; Environmental Engineering; Hydraulic Engineering
• Online Access: https://uknowledge.uky.edu/ce_etds/88; https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1091&context=ce_etds

Fluviokarst landscapes are dominated by both fluvial and karst features. Interpreting hydrologic pathways of fluviokarst can be confounded by the unknown connectivity of the various flow regimes. A combined discrete-continuum (CDC) hybrid numeric model for simulating the surface and subsurface hydrology and hydraulics in fluviokarst basins was formulated to investigate fluviokarst pathways. This model was applied to the Cane Run Royal Springs basin in Kentucky USA. A priori constraints on parameterization were avoided via multi-stage optimization utilizing Sobol sequencing and high performance computing. Modelling results provide evidence of hydrologic pathways dominated by fracture flow, epikarst transfer and runoff. Fractures in karst basins with high fracture-matrix permeability ratios may influence both springflow and streamflow. Swallet features can be as important as spring features as they are sink features in streamflow during hydrologic events. Inflections in spring hydrographs represent shifts in the surface-subsurface connectivity via the fractures, as opposed to shifts in dominant storage zones. Existing methods of dual- and triunal hydrograph separation of karst springflow may not be directly transferrable to fluviokarst springs. The numerical model herein has advantages of suggesting dominant pathways in complex terrane and highlighting unforeseen surface-subsurface connectivity. However, disadvantages include computational expense and previous site studies.