The Everglades Mitigation Bank (EMB) is a private mitigation bank owned by Florida Power & Light (FPL) covering 13,249 acres of wetland in southern Miami-Dade County. The area was characterized by hyper-saline conditions until remediation work began in 1996 to restore the area to its natural state. The reconnection of freshwater sheet flow from the north through installation of culverts is expected to facilitate the restoration of vegetation zones.
As part of the Mitigation Monitoring Plan (MMP), FPL commissioned Normandeau Ltd and APEM Ltd to undertake high resolution aerial (HRA) surveys of the site. The first HRA survey was flown in December 2013 with multispectral imagery captured at 5cm resolution. Specialist photogrammetric software was used to generate a number of outputs including RGBN and NDVI mosaics and an extracted tree height layer for each assessment area (AA). The datasets were pulled together in an Expert System to classify each AA into a set of pre-defined vegetation cover types. High-resolution 3D technology was used in the AA’s to divide the habitat into three further zones (sawgrass, Juncus/ Distichlis, and coastal mangrove). This was undertaken for two surveys (2013 and 2014), with a third project currently underway.
Results/Conclusions
The analyses carried out were used to calculate the percentage cover of each vegetation type in each zone and provide a robust, quantifiable measure of the impacts that the restoration work is having on the environment through this innovative aerial based technique. Statistics on vegetation height were also provided to help assess the success of vegetation plantings in area.
A comparison of the datasets showed the main freshwater habitat zones remained relatively similar between the 2013 and 2014 aerial surveys with minimal change recorded in habitat coverage. In the area to the south of the levee, inspections of the boundaries in GIS show the 2013 habitat zones broadly match those of 2005. There is, however, evidence of a southern advance of Juncus/Distichlis in areas along the boundary between 2005 and 2014 (+0.211km2). Visual inspection of the imagery indicated increased growth in the new planting areas. This information has provided invaluable information for the ongoing management of the restoration project.