South Florida Water Management District the Lake Okeechobee Stage-Area-Capacity Lookup Application (2004-Single Process)

Article excerpt

System Summary

The Lake Okeechobee Stage-Area-Capacity (LOSAC) Lookup Application is an intuitive, interactive, and dynamic Web application based on HyperGIS. It displays the current, historical, or hypothetical Lake Okeechobee conditions that include lake stage, area, capacity, and depth information as well as their trends.

LOSAC displays the most current Lake Okeechobee conditions obtained from the real-time lake-stage (water-level) reports on the external Web sites operated by the U.S. Army Corps of Engineers (USACE) and the Operations and Maintenance Department at the South Florida Water Management District (SFWMD). The corresponding lake area and capacity are calculated with both geographical information system (GIS) and a mathematical method based on a polynomial stage-storage function. The results are converted to various units to satisfy most users' needs. Based on a digital elevation model (DEM), a bathymetry map illustrates the related depths in the lake at the given stage; while a stage-area-capacity chart presents stage-area and stage-capacity curves that reveal the changing area and capacity along with the corresponding stages. Precise readings to the lake conditions are included in a table. In addition, LOSAC features a dynamic playback of time series of archived data of the lake, and direct retrieval of historical data with a calendar. Using animated buttons, users can browse back and forth through the stage data in the archive and display associated stage, lake-area, capacity, and bathymetry data. A rapid-mode playback shows the changes of the lake over time. The archive is updated regularly. The interactive Web interface of LOSAC also allows users to look up the lake-area and capacity data by entering a hypothetical lake stage or dragging a slider bar.

Prior to its development, the current and historical water-level data were available only in static text format on separate sites. Users had to use half a dozen individual GIS and mathematical tools to build lake-area and capacity information, and manually assemble them from different departments and agencies. LOSAC automates the whole process by integrating Active Server Page (ASP), MS SQL Database, and GIS with a front end built in Dynamic HTML (DHTML), JavaScript, and Visual Basic script, serving as a one-stop source for the current, historical, and hypothetical lake conditions with dynamic contents by an interactive and fun-to-use graphical user interface (GUI) (see Figure 1).

The core of LOSAC is an agent capable of collecting real-time data from partners' Web sites without interfering or burdening the information providers, resulting in a more efficient information flow. It supports multiple modeling methods to calculate the lake conditions in various formats, which is valuable both to the researchers for better understanding of the real-world situation and to the managers for better decision-making processes. LOSAC employs reusable modules, which allow easier function expansion, better background data upgrade, and easier switching between external information providers in case of system downtime or a network outage. Such an object-oriented approach can save time and money in developing, maintaining, and upgrading the system, and in improving the system's reliability. It is also easy to customize information for different users, enrich static contents with multimedia or animation, and expand contents into other formats for mobile devices for more effective communications. The browser-detection technique can serve customized contents tailored for a particular browser. The result is an integrated system that can provide an intuitive, dynamic, and interactive visualization tool for restoration scientists, water-supply planners, emergency managers, and anyone else who needs to access the current, historical, or hypothetical Lake Okeechobee conditions.

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Motivation for System Development

LOSAC grew out of popular demand for water-level, lake-area, and potential water-supply-capacity information in Lake Okeechobee during the unusual water shortage period in 2000--2001. …