309 - Coupling the Modelling of Continuity with Fingerprinting to Quantify Sediment Transport for Karst Streams and Caves

Predictive sediment transport modeling in karst streams and caves remains under-developed. Karst systems are typically highly connected and quickly transport sediment from streams to caves to springs. Resuspension times of previously deposited sediment are unknown and make predicting the sediment flux in karst systems difficult. The use of organic matter tracers, such as carbon and nitrogen stable isotopes, provides a potential tool to assist with resuspension estimates, so long as any non-conservativeness from degradation processes at deposition sites can be accounted for, as needed. Numerical modelling of sediment continuity and data-driven sediment fingerprinting methods were applied independently, in prior research, to gain knowledge of sediment flux and source. In this model formulation, the two methods are coupled to a system of equations that can be optimized using sediment transport modelling methods. We provide new results of this modelling advancement for a highly interconnected karstic stream and cave system located in the inner bluegrass karst region of central Kentucky, United States. Data were collected using high-resolution sensors, flow measuring devices, and several in situ sediment samplers to collect fluvial sediment for analyses of carbon and nitrogen elemental and isotopic composition. Results presented will include: (1) high resolution sensor measurements and stable isotope data of sediment that provides a multi-objective function for optimizing the modelling framework; (2) results of sediment resuspension rates for externally sourced sediment that is deposited in karst caves, including estimates of hydrologic and biogeochemical controls on residence time; (3) results of degradation rates for non-conservative tracers; and (4) results of sediment transport rates from the new numerical model that couples sediment continuity with sediment fingerprinting.