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EDEN and EVE—Getting the Water Right in Paradise
In the winter months, it’s easy to understand why people flock to the vibrant paradise that is south Florida. At the heart of that paradise is a vast landscape of endless marshes, dense mangroves, towering palms, and tropical fauna—the Everglades. This watery wonder, however, has been altered over the past 100 years by the development of canals and levees, built to provide flood control and water management. The Everglades’ natural flow of freshwater has been disrupted and drained off to the coasts, degrading the wetlands that so much wildlife depended upon. The current Everglades are still a paradise to many, but the Everglades of the past no longer exist. The need to preserve south Florida’s natural ecosystems, combined with managing water supply and flood controls, pushed agencies and organizations in the late 1990s to come together and develop a plan to restore the Everglades. In 2000, the Comprehensive Everglades Restoration Plan (CERP) was approved.
Successful restoration of the Everglades depends on restoring or approximating the former natural volume, timing, and distribution of wetland sheetflow—the downslope movement of water as a continuous film over the land surface—and the corresponding response of the ecosystem. Critical to this process is the Everglades Depth Estimation Network (EDEN), which provides online water-depth information for the entire freshwater portion of the Greater Everglades. Water depth is the difference between the ground-surface elevation and the water-surface elevation, or water level. Water levels in the Everglades vary in response to such factors as rainfall and releases of water from canals and levees. They greatly affect the ecology and biology of the region: too much or too little water will determine whether alligators can lay their eggs, whether wading birds can nest—in general, whether the conditions are right to support the ecosystem.
Real-time water-level measurements are provided to EDEN from a network of more than 280 gages maintained by multiple State and Federal agencies, including the South Florida Water Management District, the U.S. Geological Survey (USGS), Everglades National Park, and Big Cypress National Preserve. To estimate water depths, EDEN integrates the real-time water-level data with ground-elevation and real-time water-surface modeling. (Learn more from the Sound Waves story "EDEN—A Paradise for Water Managers?" and this USGS EDEN Fact Sheet .) This integration provides scientists and managers with carefully estimated water depths from 1991 to the present for the entire freshwater portion of the greater Everglades, all available online. Presenting the integrated data on a 400-meter grid spacing, EDEN offers a consistent and documented dataset that can be applied by scientists and managers to guide large-scale field operations, to integrate data on hydrologic (water-related) and ecological responses, and to support biological and ecological assessments. Data from EDEN assist the measurement of ecosystem response for the implementation of CERP.
Two recent additions to EDEN, described here, showcase the value of hydrologic information and how it can be used.
Explore and View EDEN (EVE)
One of the main components of EDEN is its distributed gage network. Water-level (gage) data are collected from multiple agencies and provided on the EDEN website to serve scientists, managers, and the public. The ability to view historical as well as recent hydrologic data allows users to observe trends as well as current conditions. The EDEN team, led by Bryan McCloskey of the USGS St. Petersburg Coastal and Marine Science Center in St. Petersburg, Florida, recently developed the Explore and View EDEN (EVE) web application to allow users to visualize this hydrologic information alongside supplemental information. At the center of a typical EVE webpage is a hydrograph (a graph showing change in a hydrologic variable over time) that displays daily mean water levels. (See example below.) Ground elevation is plotted on the hydrograph to allow users to see when a gage is dry. Rainfall and evapotranspiration data can also be displayed, presenting a more complete picture of the water cycle.
Users of EVE specify a date range, select a gage or a group of gages (useful when viewing regional hydrology), select the parameters that interest them, and then choose whether to view the data graphically, in a table, or both. The data are also available for download. Provisional data and real-time data are color-coded to bring attention to the status of the gage data. (Real-time data have received little or no review; provisional data have received some review. Both data types may undergo substantial revision before they are considered final; see What are the differences between real-time, provisional, and final surfaces?) The hydrograph view is also interactive, allowing the user to move the mouse over the hydrograph to obtain readings for specific days. Clicking and dragging the hydrograph zooms in or out of the hydrograph. There is also a smaller hydrograph that lets users zoom in to a narrower range of dates.
Monitoring Water Levels at Tree Islands
When a new water-control plan was instituted in 2012 as a part of CERP, State and Federal agencies needed a real-time reporting tool for monitoring water levels at tree islands—areas formed by a slight rise in elevation that results in less frequent flooding and allows woody shrubs and trees to take hold. Local Native American tribes have used tree islands in the Everglades as burial sites for human remains and funerary objects and have expressed strong objection to the unnatural inundation of tree islands under current or future Everglades ecosystem restoration. At the request of local tribes, the USGS recently developed an EDEN application (Monitoring Water Levels Under the Everglades Restoration Transition Plan (ERTP) Using EDEN) that reports near-real-time inundation at about 400 tree islands in two Water Conservation Areas and Everglades National Park. The maximum ground elevation at each tree island is compared with the daily water level modeled by EDEN to determine if the tree island has been inundated. An automated email is sent to stakeholders to report tree islands that have been inundated each day. In addition, the EDEN website provides users with access to a map of the impact area where tree islands are color-coded for the status of inundation on a daily basis.
To learn more about USGS research in the Everglades, read “Science in Support of Everglades Restoration—Some Contributions from the USGS in Florida” and visit the South Florida Information Access (SOFIA) Integrated Science for the Greater Everglades and EDEN websites.
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