Zeitschrift für Geographie und Naturkatastrophen
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Study on groundwater flow and salinity distribution cycling controlled by seawater/freshwater interaction in Woodville Karst Plain, Florida, USA

Bill X Hu, Zhongyuan Xu and Zexuan Xu

Seawater intrusion due to sea level rise and climate change could significantly damage coastal groundwater resources, in Florida, the flattest state in the US. Based on field observation and measurement, a three phase conceptual model was proposed for describing seawater and fresh water interaction at Woodville Karst Plain(WKP), Florida, a typical karst system in the Floridan aquifer. Then, a numerical model is developed to quantitatively investigate the groundwater flow cycling and seawater intrusion to the groundwater system. The karst conduit network in the aquifer acts as fast flow pathways for groundwater flow and solute transport, which allows seawater deeply intrude the aquifer. Wakulla Spring, an inland spring 11 miles from the coast and the coastal submarine spring, Spring Creek Spring Complex are connected through the conduit network. The flow direction between the two springs varies due to rainfall condition in the region, thus the discharges at two karst springs are used to estimate the location of seawater/freshwater mixing interface. The salinity distribution and seawater intrusion to the conduit system are very sensitive to precipitation variation. Furthermore, predictions are made for sea level rise and hurricane event with extreme precipitation scenarios. The results show that the seawater could intrude to the inland spring and contaminant the fresh water system if sea level rise 1.0 m. A large area of the aquifer would be contaminated in a long-term dry season.