Long-term (11 years) study of water balance, flushing times and water chemistry of a coastal wetland undergoing restoration, Everglades, Florida, USA

Abstract

Upstream water diversions have significantly reduced freshwater flow to coastal wetlands of the Everglades. The purpose of this research was to investigate the water balance, flushing time, and water chemistry of Taylor Slough; one of the main natural waterways of the coastal Everglades, during its early stages of restoration. Both the water balance and flushing times were calculated on a monthly basis from 2001 to 2011. Surface water chemistry was analyzed using 3-day composite samples collected every 18h. Current restoration efforts have been able to increase surface water inputs to southern Taylor Slough, but rainfall was still the dominant water input. Flushing times varied between 3 and 78days, with the highest values occurring in December and the lowest in May. Flushing times were negatively correlated with evapotranspiration (ET), but were longer when surface water volume exceeded ET and shorter when ET exceeded water volume. Surface water concentrations of calcium and chloride along with total nitrogen and total phosphorus were negatively correlated with flushing times. The results herein suggest that in coastal wetlands with low quantities of surface water inputs, ET and surface water volume influenced by rainfall are the most dominant factors influencing flushing times and water chemistry. Increased surface water inflows with additional restoration efforts would be expected to increase surface water volumes into southern Taylor Slough, thereby increasing flushing times and decreasing ion and nutrient concentrations.