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Water Resources Research
Transport rates and residence time in the subsurface are critical parameters for understanding water‐rock interactions for efficient contaminant remediation. This paper presents a methodology for assessing flow and transit time of water through hydrological systems, with specific applications to karst systems and implication for hydraulics of a conduit system surrounded by a porous and permeable intergranular matrix. A time variant cross‐correlation function analysis is applied to bivariate time series that characterize mass transfer, assuming a stationary system using sliding windows of various sizes. We apply the method to 1 year long temperature records in the Santa Fe River (north central Florida) measured at (1) the River Sink, where all the incoming surface water drains into a sinkhole, (2) Sweetwater Lake, where the river resurges into a 500 m long karst window, and (3) the River Rise, where the water discharges from a first‐magnitude karst spring. Results are compared with those obtained using specific conductivity. Estimated residence time ranges from less than 1 day during floods to more than 15 days during base flow within the 8000 m flow path between the River Sink and the River Rise. Results are used to characterize geometric, hydraulic, and hydrodynamic properties of this sink‐rise system with strong matrix‐conduit interactions. These properties are critical to the chemical and physical behavior of surface water–groundwater mixing. Our results also have direct implications for sampling strategies and hydrograph separation of many karst systems with different degrees and types of matrix porosity and permeability.
Time series analysis; Cross‐correlation; Natural tracer; Karst; Allogenic recharge; Santa Fe River
Digital Object Identifier (DOI)
Bailly-Comte, V.; Martin, Jonathan B.; and Screaton, E. J., "Time variant cross correlation to assess residence time of water and implication for hydraulics of a sink‐rise karst system" (2011). KIP Articles. 6782.