Historical Approach to Determining Wetland Impacts from Groundwater Drawdowns through Aerial Photo Interpretation

Chapter 373, Florida Statutes, requires the Water Management Districts to preserve natural resources, fish and wildlife in addition to providing water for all reasonable, beneficial uses. The wetland hydroperiod, and the flora and fauna that inhibit these areas, are affected by substantial groundwater withdrawals. Regulatory agencies face a complex assignment in developing a scientific rationale to quantify the effects of drawdown on wetland systems. Numerous inter-related factors control the hydro-biologic responses in a given area. The goal of this project was to develop a methodology to compare water table declines with plant community changes (loss of wetland acreage) at various distances from the center of pumping. Results of the study could be used in developing regulatory guidelines for the protection of wetlands identifying data collection requirements and for determining appropriate mitigation efforts.

BFA provided hydrologic support to Geonex Martel, Inc. for this project. Data was obtained from numerous sources and BFA complied and evaluated rainfall, pumpage and water levels data for five study areas. A methodology was developed to correlate results with wetland vegetative changes observed on historical aerial photography. The hydrologic records (duration, frequency, location) for these selected study areas were determined to be inadequate to correlate the hydrologic stresses with wetland vegetative changes observed on historical aerial photography. However, a methodology was developed and data requirements were identified to satisfy the goals of this project.