LONG-TERM WETLAND IMPACTS EXPLAINED BY PREVIOUS HISTORIC GROUND WATER WITHDRAWALS

During a recent enviro-hydrologic assessment in a portion of central Florida's Green Swamp, an area of distressed forested wetlands was found. The evaluation of these wetlands concluded that they were impaired by a reduction in the water table that had occurred many years prior. This impairment was puzzling in that it appeared to be long-standing in nature, likely decades-old, but there were not any obvious indications of sufficient land alterations for drainage that might have caused the impacts. The hydrogeologic setting of the area is that of leaky-confinement. However, there did not currently seem to be any large-scale ground water withdrawals in the area that might explain the impacts. Based on this information, the question arose as to whether the impacts could have been caused by historical ground water withdrawals that no longer are taking place. An analysis of land alteration effects and historical ground water withdrawals in the area was undertaken utilizing a literature search, review of historical aerial photos, hydrographs analysis, and ground water flow modeling. Analysis of the hydro-ecology of the wetlands was also performed. The result of this analysis indicates that nearby historical ground water withdrawals that have since ceased to occur are the primary reason for the wetlands degradation.