Florida Aquifer Vulnerability Assessment (FAVA)
Contact: Alan Baker
In ground-breaking research on aquifer protection in Florida, a GIS modeling technique has been applied to predict the vulnerability of Florida’s aquifer systems to surface sources of contamination. This technique is adapted from GIS-based mineral-potential mapping and is known as Weights of Evidence (WofE). The WofE method combines evidence from known occurrences (training points) with spatial data (i.e., maps) to calculate a statistical prediction based on Bayesian theory.
The Florida Aquifer Vulnerability Assessment (FAVA) applies the WofE method to the three principal aquifer systems in Florida through the use of the Arc Spatial Data Modeler (ArcSDM) within the ArcView and ArcMap platforms. The ArcSDM extension facilitates assessment of spatial datasets, conditional independence, prediction uncertainty and validation, and provides other modeling techniques and statistical tools.
In FAVA models, training points consist of data from wells reflecting background water quality. Parameters used in the models to reflect known occurrences of aquifer vulnerability in the natural hydrogeologic system include dissolved oxygen and total dissolved nitrogen. Input spatial data, also known in WofE as “evidential themes” include combinations of several improved or
statewide GIS coverages such as:
|Depth to water table
|Hydraulic head difference
|Thickness of confinement
|Distance to karst features
|Aquifer system overburden
To maximize scientific defensibility of the relative vulnerability maps (WofE response themes), models are validated using independent training data sets, training-point subsets and by demonstrating lack of correlation between land use and posterior probability.
Aquifer vulnerability maps are an important resource for planners, developers, resource-management professionals and policy makers to facilitate protection of Florida’s ground-water resources.
For more information see:
Arthur, J.D., Wood, H.A.R., Baker, A.E., Cichon, J.R., Raines, G.L., 2007, Development and Implementation of a Bayesian-based Aquifer Vulnerability Assessment in Florida: Natural Resources Research, Vol. 16, No. 2, p. 93 - 107.
Arc News January 09 Article
Geological Society of America FAVA Abstract October 2008