Flow Characterization in the Santee Cave System in the Chapel Branch Creek Watershed, Upper Coastal Plain of South Carolina, USA

Abstract

Karst watersheds possess both diffuse and conduit flow and varying degrees of connectivity between surface and groundwater over spatial scales that result in complex hydrology and contaminant transport processes. The flow regime and surfacegroundwater connection must be properly identified and characterized to improve management in karst watersheds with impaired water bodies, such as the Chapel Branch Creek (CBC), South Carolina watershed, which has a long-term sampling station presently listed on an EPA 303(d) list for phosphorous, pH, and nitrogen. Water from the carbonate limestone aquifer of the Santee Cave system and spring seeps in the CBC watershed were monitored to characterize dominant flow type and surface-groundwater connection by measuring dissolved calcium and magnesium, total suspended solids, volatile suspended solids, alkalinity, pH, specific conductance, and stable isotopes (d 18 O, d 2 H). These measurements indicated that the conduit flow to Santee Cave spring was recharged predominantly from diffuse flow, with a slow response of surface water infiltration to the conduit. Qualitative dye traces and stage elevation at Santee Cave spring and the adjacent Lake Marion (equal to the elevation of the flooded portion of CBC) also indicated a relation between fluctuating base level of the CBC reservoir-like embayment and elevation of the Santee Limestone karst aquifer at the spring. Methods described herein to characterize the flow type and surface-groundwater connection in the Santee Cave system can be applied not only to watershed management in the Chapel Branch Creek watershed, but also to the greater region where this carbonate limestone aquifer exists.

Integrated Use of Geological, Geophysical, Radiocarbon and Stable Isotopes Data for Tracing the Conduit Flow Paths in a Small Karstic Aquifer: Poocher Swamp Freshwater Lens, South Australia

“…This is particularly important in arid and semi-arid countries as the demand for water is ever increasing for agriculture, industry and community water supplies (WWRD, 2015). Karst aquifers possess both diffuse and conduit flow and varying degrees of connectivity between surface and groundwater over spatial scales that results in complex hydrology (Edwards et al, 2013). The surface-groundwater connection and flow regime must be properly identified and characterized to improve management of karst aquifers.…”

“…Geochemical and isotopic data have been used in numerous studies in different karst regions to characterize the flow in carbonate aquifers and degree of surface-groundwater connections (Edwards et al, 2013). Knierim et al (2015) show that stable isotope analyses are valuable in karst settings.…”

SWAT Model Prediction of Phosphorus Loading in a South Carolina Karst Watershed with a Downstream Embayment

“…Both the monitoring and modeling approaches provided a better understanding of the hydrologic and nutrient cycling and transport (flow pathways) processes on the watershed of interest. Potential effects of karst features and interactions with Lake Marion level on hydrology and potential flow paths of the CBC watershed have been recently discussed by [8,9].…”

“…Accordingly, in the Opequon Creek watershed study, [26] found that a SWAT-Karst model that used the HRU to represent sinkholes had a more notable impact in the watershed hydrology than SWAT-B&B using a pond to represent sinkholes; the author reported that the SWAT-karst and the SWAT-B&B version performed better than the SWAT alone for predicting streamflow in a karst-influenced watershed. Most recently, [27] used the SWAT model to simulate the monthly streamflow pattern and dynamics of the karst affected CBC watershed tributaries and its embayment adjacent to Lake Marion, water levels of which dynamically influence the hydrology and water quality of the CBC system [8,9]. Results demonstrated the substantial influence on the water balance of the karst features with conduit and diffuse flow as an explanation [9] for the missing upstream flows appearing via subsurface conveyance to the downstream cave spring [8] providing a more accurate simulation at the embayment outlet [27].…”

“…Most recently, [27] used the SWAT model to simulate the monthly streamflow pattern and dynamics of the karst affected CBC watershed tributaries and its embayment adjacent to Lake Marion, water levels of which dynamically influence the hydrology and water quality of the CBC system [8,9]. Results demonstrated the substantial influence on the water balance of the karst features with conduit and diffuse flow as an explanation [9] for the missing upstream flows appearing via subsurface conveyance to the downstream cave spring [8] providing a more accurate simulation at the embayment outlet [27]. Results also highlighted influences of downstream lake levels and karst voids/conduits on the watershed hydrologic balance [9].…”