Example of Beach Monitoring GIS System
State public health agencies, in conjunction with local governments, routinely monitor the bacterial water quality of the Southeast’s ocean swimming beaches. These monitoring data are used to post swimming advisories, with the goal of allowing the public to make informed decisions concerning recreating in waters presenting a potential for adverse health effects. Per current EPA guidelines, agencies test for the bacterial indicator, Enterococcus, to determine bacterial water quality and issue water quality swimming advisories. The method used to determine Enterococcus concentrations requires a 24-hour incubation period before results can be assessed. Decision makers are therefore issuing and lifting advisories based on the previous day’s water quality. In partnership with the South Carolina Department of Health and Environmental Control (SCDHEC), a collaborative team including the University of South Carolina and University of Maryland, is enhancing a user application with new models and an automated, database driven tool for bacteria estimates and visualization of model results for enhanced prediction and analysis of this public health concern.
The project builds on previous efforts and incorporates new models that provide rainfall estimates using radar-based data which can be averaged over a watershed area. These radar data provide improvements to existing tools by allowing spatial estimates to be averaged over the relevant watershed area instead of applying point estimates and allowing for automated integration of remotely sensed data, eliminating the need for SCDHEC’s costly and time consuming maintenance of the rain gauge network.
A dynamic database is being developed that integrates the real and near-real time ocean observing data (including air temperature, water temperature, wind direction) and predictive models and executes the equations and decision tools specified in the models. GIS-based tools allow direct access to monitoring data, the models, and user-friendly presentations to provide processed information required for making swimming advisory decisions.
SCDHEC has implemented the initial suite of pre-emptive beach swimming advisory models as a tool in determining the issuance of beach swimming advisories in Horry County, SC on an operational basis from May 15 through October 15 (beach swimming season). Benefits to SCDHEC include eliminating the need for updates and maintenance of the rain gauge network; improved timeliness by providing robust decision support well in advance of verification by biological sample cultures; and improved accuracy by providing reliable forecasts of beach hazards meriting closures, with reduced false positives. These tools are also eliminating unwarranted advisories that negatively impact coastal economic and tourist activity.
"This model has reduced the sampling burden for our Regional staff; but the major benefit has been the Department's quicker response time for posting beach advisories and subsequent enhancement of our agency's primary mission of protecting the public health."
David E. Wilson, PE
Chief, Bureau of Water, SCDHEC
While the specific geographic focus of this effort is on swimming beaches in SC, the techniques implemented and tools developed are transferrable to other swimming beaches in the Southeast. Scientists would also like to increase observing asset (i.e., buoys and radar) coverage for improved spatial resolution of data; assess utility of modeled output for salinity and currents; and understand beachgoer data (i.e., who is using the beach).