Detection of coastal and submarine discharge on the Florida Gulf Coast with an airborne thermal-infrared mapping system

Professional Geologist
By: , and 



Along the Gulf Coast of Florida north of Tampa Bay lies a region characterized by an open marsh coast, low topographic gradient, water-bearing limestone, and scattered springs. The Floridan aquifer system is at or near land surface in this region, discharging water at a consistent 70-72°F. The thermal contrast between ambient water and aquifer discharge during winter months can be distinguished using airborne thermal-infrared imagery. An airborne thermal-infrared mapping system was used to collect imagery along 126 miles of the Gulf Coast from Jefferson to Levy County, FL, in March 2009. The imagery depicts a large number of discharge locations and associated warm-water plumes in ponds, creeks, rivers, and nearshore waters. A thermal contrast of 6°F or more was set as a conservative threshold for identifying sites, statistically significant at the 99% confidence interval. Almost 900 such coastal and submarine-discharge locations were detected, averaging seven to nine per mile along this section of coast. This represents approximately one hundred times the number of previously known discharge sites in the same area. Several known coastal springs in Taylor and Levy Counties were positively identified with the imagery and were used to estimate regional discharge equivalent to one 1st-order spring, discharging 100 cubic feet per second or more, for every two miles of coastline. The number of identified discharge sites is a conservative estimate and may represent two-thirds of existing features due to low groundwater levels at time of overflight. The role of aquifer discharge in coastal and estuarine health is indisputable; however, mapping and quantifying discharge in a complex karst environment can be an elusive goal. The results of this effort illustrate the effectiveness of the instrument and underscore the influence of coastal springs along this stretch of the Florida coast.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Detection of coastal and submarine discharge on the Florida Gulf Coast with an airborne thermal-infrared mapping system
Series title Professional Geologist
Volume 48
Issue September/October
Year Published 2011
Language English
Publisher AIPG
Publisher location Thornton, CO
Contributing office(s) St. Petersburg Coastal and Marine Science Center
Description 8 p.; maps (col.)
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Professional Geologist
First page 42
Last page 49
Country United States
State Florida
Other Geospatial Gulf Coast