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Evaporation From the Interior of Lake Okeechobee—A Large Freshwater Lake in Florida, 2013–16

Scientific Investigations Report 2024-5040
Prepared in cooperation with the South Florida Water Management District
By:  and 
https://doi.org/10.3133/sir20245040

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Abstract

In 2012, a platform at the approximate center of Lake Okeechobee in central Florida was instrumented to continuously measure evaporation with the Bowen-ratio energy-budget method as part of a long-term partnership between the South Florida Water Management District and the U.S. Geological Survey. The primary goal for the study was to quantify daily rates of open-water evaporation. A secondary goal was to assess differences in evaporation rates among alternate methods and determine if instrumentation and operational expenses associated with the Bowen-ratio method could be reduced.

Mean annual evaporation from Lake Okeechobee for 2013–16 was about 1,825 millimeters per year. Annual evaporation from 2013 to 2016 was 1,760, 1,840, 1,810, and 1,890 millimeters per year, respectively. These evaporation rates are among the highest rates observed in Florida based on scientifically vetted methods such as evaporation pans, lysimeters, eddy-covariance, or Bowen-ratio methods. The high evaporation rates are largely a result of frequent clear-sky conditions over the interior of Lake Okeechobee, which allows solar radiation to reach the water surface and drive open-water evaporation. Cloud formation over the interior of Lake Okeechobee is suppressed because of a relatively large heat capacity for water that buffers convective fluxes of air that form clouds while rising and cooling.

Estimated evaporation rates obtained using five alternative methods were compared to measured Bowen-ratio energy-budget daily, monthly, and annual evaporation: the Penman, Priestly-Taylor, Mass-Transfer, Simple, and Turc equations. All five methods performed relatively well (within 10 percent of the Bowen ratio annual totals). The Penman, Priestley-Taylor, and Mass-Transfer methods captured relatively large evaporation rates that occurred in the winter due to cold fronts, because these methods account for large wind speeds and vapor pressure deficits associated with the regional cold fronts. For operational implementation, the Simple, Mass-Transfer, or Turc methods are likely preferable because of their simplicity, limited data requirements, and improved accuracy for computing monthly and annual evaporation totals. The Turc equation computed monthly evaporation within 8 percent of the Bowen-ratio method, while requiring only air temperature and solar radiation data. The Simple equation achieved similar accuracy while requiring only solar radiation data.

Suggested Citation

Shoemaker, W.B., and Wu, Q., 2024, Evaporation from the interior of Lake Okeechobee—A large freshwater lake in Florida, 2013–16: U.S. Geological Survey Scientific Investigations Report 2024–5040, 17 p., https://doi.org/10.3133/sir20245040.

ISSN: 2328-0328 (online)

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Table of Contents

  • Abstract
  • Introduction
  • Methods for Computing Lake Evaporation
  • Results and Discussion
  • Summary
  • Acknowledgments
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Evaporation from the interior of Lake Okeechobee—A large freshwater lake in Florida, 2013–16
Series title Scientific Investigations Report
Series number 2024-5040
DOI 10.3133/sir20245040
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Caribbean-Florida Water Science Center
Description Report: vi, 17 p., 3 Data Releases
Country United States
State Florida
Other Geospatial Lake Okeechobee
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details