TEN YEAR STUDY ON RESTORATION PROJECTS AND THEIR EFFECTS ON FLUSHING TIMES, WATER QUALITY, WATER CHEMISTRY, AND WATER SOURCES IN THE COASTAL EVERGLADES

The Everglades, located in southern Florida, is a dominantly freshwater coastal wetland ecosystem that has experienced many alterations and changes led by urbanization and water management practices. The Comprehensive Everglades Restoration Plan has the final goal of restoring natural flow and clean water to the Everglades while also balancing flood control and water supply needs of the south Florida population. One way to assess the success of restoration projects is to observe long-term hydrological and geochemical changes as the projects undergo completion. The purpose of this research was to investigate the effects of restoration on the water balance, flushing time, and water chemistry of Taylor Slough; one of the main natural waterways located within the coastal Everglades. The major parameters for the water balance (precipitation, evapotranspiration (ET), surface water storage, inflow and outflow) were obtained from the U.S. Geological Survey and Everglades National Park databases. A water balance equation was used to solve for groundwater-surface water exchange. Watershed flushing times were estimated as the surface water volume divided by the total outputs from the watershed. Both the water balance equation and water flushing time were calculated on a monthly time step from 2001 – 2011. Water chemistry of major ions was analyzed on water samples, 3-day composites collected every 18 hours from 2008 – 2012, and correlated with water flushing times. Stable isotopes of oxygen and hydrogen of water samples were obtained to support the dominant inputs of water into Taylor Slough as identified by the water budget equation. Results show the highest water flushing times typically occurring in December with the lowest flushing times occurring in May throughout the ten-year period. Water flushing times were found to be negatively correlated with ET, indicating the major influence of ET on the water budget. Surface water ion concentrations were also found to be negatively correlated with water flushing times indicating the influence of precipitation and ET on surface water chemistry. Stable isotope and ion data corroborated the influence of precipitation in the freshwater portion of Taylor Slough. Downstream and closer to the coastline, stable isotope and ion data indicate a marine influence on the water chemistry.