Design of real-time and long-term hydrologic and water quality wetland monitoring stations in South Florida, USA

Abstract

Hydrologic regimes in tropical and subtropical regions (e.g. hurricanes, tropical storms, and droughts) impact biogeochemical processes in created and restored wetlands with variability of wet/dry seasons and extreme weather events. Our South Florida Wetland Monitoring Network (SFWMN) with three real-time hydrologic, water quality, and meteorological field stations was established by the Everglades Wetland Research Park of Florida Gulf Coast University in the subtropical Southwest Florida, USA, beginning in 2012. The stations include a restored freshwater marsh (RFM) and adjacent meteorological field station; a restored brackish water marsh (RBM); and a created freshwater treatment wetland system and adjacent meterological station (CFTW). Continuous observations of water depth, temperature, salinity, and pH for the period of January 2012 to January 2016 indicate significant differences among the restored freshwater marsh, the restored brackish marsh, and the created freshwater treatment wetlands for water temperature and pH for wet and dry seasons. The brackish wetland salinity fluctuated between 26.16 (in the dry season) to 1.03ppt (in the wet season).The real-time dataset allowed up-to-date information of the frequency and duration of severe weather events illustrating, for example, that 70% of the 2012 annual rainfall (1129mm) occurring in July and August with a 75.4mm precipitation during one event—tropical storm Isaac on August 26–28, 2012. This storm led to a water stage peak in the brackish wetland due to excessive watershed runoff, not tidal surges, and salinity decreased from 22.3 to 5.5ppt.The coefficient of variation (CV) for water depth and water quality from all wetland monitoring stations exhibited similar variations during all seasons, except when the salinity for the brackish marsh (RBM) had the highest CV values (1.02) in the wet season. Principal component analysis (PCA) at each station identified the variance in water depth and water quality parameters as due to seasonal changes of precipitation in distinct wet and dry seasons. The data from these monitoring stations are also used for research by scholars and students as well as for teaching a better understanding of wetlands dynamics and function in the classroom. As a whole, these stations are being used to bring awareness about the fragile and unique hydrological conditions of wetlands in subtropical Southwest Florida, especially for long-term conditions related to sea level changes and more frequent tropical storms.