As a component of the Suwannee River Water Management District-funded Middle Suwannee Basin Springshed Interpretation project, FGS researchers have recently initiated two dye trace studies aiming to refine Troy Spring’s springshed and determine Falmouth Spring’s interconnectivity with various other springs. Environmentally safe fluorescent dyes are a proven method for confirming groundwater flow connection in karst terrain.

Rhodamine dye was introduced into Falmouth Spring (which is actually a karst window) in Suwannee County in early September. Over the next 12 days, the dye was detected in Lime Spring (Little Gem), Lime Sink Run, Ellaville Springs, and Suwannacoochee Springs, confirming a groundwater connection. Automated water samplers, backed up by charcoal packets, were deployed at the springs to capture the dye as it arrived. Since the dye is not typically detectable to the naked eye downstream, samples were sent to a specialized laboratory for analysis.

The second dye trace was initiated in the Little River Trace (Suwannee County) in early October. Rhodamine dye was released into a karst window and fluorescein dye was released into a swallet. Both dye introduction sites were located using LiDAR imagery and field reconnaissance. Automated water samplers and charcoal packets were installed at Mearson, Troy and Little River Springs. None of the water samples for this trace have been analyzed at present, however, analysis of the first few sets of charcoal packets indicate both rhodamine and fluorescein dye emerged at Little River and Troy Springs with only fluorescein dye being detected at Mearson Spring. The results of these traces will be used in conjunction with other data in the interpretation of land areas contributing flow to some of the springs within the basin.

Contact person/info: Tom Greenhalgh  

The National Geologic Map Database (NGMDB) is a congressionally mandated project jointly led by the Association of American State Geologists (AASG) and the U.S. Geological Survey (USGS). The database is a compilation of over 88,000 geologic reports, maps and other geologic information, some of which date back to the 1800s. The database is searchable and also provides references for each geologic product found in the database.

The data in the NGMDB are served through a web-based viewer called MapView. This interactive and scalable viewer allows the user to scale up and down (zoom in and out) as needed, in areas where geologic map data exist. Users can see geologic map data from different time periods, map scales, and projects all by the click of a mouse. Instead of aerial imagery as used in databases like Google Earth, the viewer displays geologic data. For the first time, this project allows access to a large and searchable archive of geoscience information by selecting a geographic region of interest on an interactive map.

The FGS has been producing surficial and bedrock geologic maps since 1907. The latest geologic maps covering parts of Florida have been produced under the STATEMAP program. This program, which has been ongoing for the past 20 years in Florida, is jointly funded by the USGS and FGS. The maps, along with other FGS map products, have been incorporated into the NGMDB.  To view the NGMDB data, visit http://ngmdb.usgs.gov/maps/mapview/

Contact person/info: Harley Means 

The FGS Applied Geoscience Services Section is actively engaged in the production of statewide potentiometric surface maps of the upper Floridan aquifer system. Potentiometric surface maps illustrate the elevation to which groundwater rises in cased wells, and can serve as one barometer of aquifer health. The mapping is being conducted in cooperation with the state’s five water management districts. The districts provide water-level measurements obtained from monitor wells twice a year in May and September. The data are converted using geo-statistical methods to 10 foot contour lines on the map representing the water-level surface of the aquifer. Maps are anticipated to be updated in December and July of each year.

Potentiometric surface maps represent a snap shot in time and do not represent the dynamic changes of water levels within the aquifer. They can, however, be compared with historic maps to determine regional water level changes over time. Such changes may also be correlated to both natural influences, such as seasonal rainfall or drought as well as anthropogenic influences.

Similar to the effort undertaken by the NGMDB, the FGS has recently produced an ArcGIS Online interactive map that depicts historic statewide upper Floridan aquifer potentiometric surface maps. Individual contour maps can be viewed by selecting the map of interest. These maps range from a pre-development upper Floridan aquifer potentiometric surface map to an upper Floridan aquifer map for September 2012. The map has colored contour lines and well points and can be viewed at different scales using a map viewer that is similar to MapView. It allows users to navigate various data layers, including the potentiometric surface layer.

Historic and current statewide potentiometric maps can be viewed on FDEP’s ArcGIS Online site at fdep.maps.arcgis.com

GIS data for historic and current statewide potentiometric surface maps can be downloaded at www.dep.state.fl.us/gis/datadir.htm

Contact person/info: Jim Cichon