Download and rasterize FDEP Upper Floridan Aquifer potentiometric surface

Usage

util_gw_getcontour(
  season = c("dry", "wet"),
  yr,
  max_records = 1000,
  verbose = TRUE
)

Arguments

season: character, "dry" or "wet".
yr: integer, year for which to retrieve data. Biannual (May/September) observations are available from approximately 2010 onward.
max_records: integer, maximum records per paginated API request. Default 1000.
verbose: logical, print download and interpolation progress. Default TRUE.

Value

A SpatRaster of potentiometric head (ft above MSL) at 1-mile resolution in the CRS of tbfullshed (EPSG 6443). Returns NULL with a warning if no features are found for the requested season/year.

Details

Downloads Upper Floridan Aquifer potentiometric surface contour lines from the FDEP / Florida Geological Survey ArcGIS REST service (https://ca.dep.state.fl.us/arcgis/rest/services/OpenData/FGS_PUBLIC/MapServer/8) and interpolates them to a 1-mile SpatRaster using inverse distance weighting (IDW).

Spatial extent: The API query covers the Tampa Bay watershed (tbfullshed) buffered outward by 40 miles (211,200 US Survey Feet), converted to WGS84. This wider extent captures high potentiometric values outside of the surficial subwatersheds that drive groundwater flow.

Interpolation: Contour line vertices are used as elevation observations and interpolated to a 1-mile grid via IDW (5-mile radius, power = 2). Cells more than 5 miles from any contour vertex are left NA to avoid extrapolation into data-sparse regions. Five passes of a 3x3 focal mean then fill small gaps. The 5-mile radius was chosen to bridge typical contour spacing in the Tampa Bay region without extrapolating into the panhandle or coastal areas.

Season mapping:

"dry" maps to May of yr
"wet" maps to September of yr

Examples

if (FALSE) { # \dontrun{
pot_dry <- util_gw_getcontour("dry", 2022)
pot_wet <- util_gw_getcontour("wet", 2022)
} # }