Hydrologic characterization of 56 geographically isolated wetlands in west-central Florida using a probabilistic method

摘要

Wetlands are important hydrological elements of watersheds that influence water storage, surface water runoff, groundwater recharge/discharge processes, and evapotranspiration. Understanding the cumulative effect wetlands have on a watershed requires a good understanding of representative water-level fluctuations and storage characteristics associated with multiple wetlands across a region. We introduce a probabilistic approach based on frequency analysis of water levels in numerous geographically isolated wetlands across the mantled karst terrain of west-central Florida, in the Tampa Bay region. This approach estimates the probabilities, or percentage of time, that water levels in a wetland or upland groundwater wells are at or below a specific elevation. We applied this hydrologic characterization to 56 wetlands in west-central Florida, and documented that standing water was present in the wetlands 61 % of the time and that these wetlands were groundwater recharge zones at least 50 % of the time over the 7 year study. Additionally, we demonstrated that various wetland types, classified according to vegetation community composition and structure, exhibit similar means, extremes and ranges in water-level behavior. We believe that this is the first paper to robustly quantify inundation frequency and recharge status in seasonally flooded wetlands at a regional scale. The analytical tool introduced in this manuscript could be used to detect, through changes in water-level frequency distribution, wetland hydrological response to different climatological or anthropogenic stressors. This tool is timely as changes in frequency distribution shape may provide early warnings of ecosystem regime change.