PROJECT LEADER:
John C. Hayes
COOPERATORS:
D. E. Linvill - Agricultural and Biological Engineering Department
FUNDING AGENCY:
USDI/National Park Service
DESCRIPTION
The Congaree Swamp National Monument (COSW) represents a unique ecosystem that combines near-virgin hardwood forest with a portion of the Congaree River floodplain. The Monument provides a vivid example of natural interaction between hydrologic events and vegetative communities. Unfortunately, the uniqueness of the Monument also makes it difficult to manage. Since it is nearly flat, slight differences in water elevation result in substantially different areas being inundated and may substantially impact the plant and animal life.
The methods used in the project are to apply various computer models for hydrologic analysis. They will be modified for this application because of the almost flat topography in the Monument and because of the complex combination of numerous creeks and three major rivers that contribute to flood events. A major creek which enters the Monument from the north has been modeled for single event storms and compared with data from several storm events. It became clear through this study that the available data of storm event and streamflow reaction were not sufficient to perform a valid calibration of the models. The continued operation of the gaging stations will hopefully provide necessary data and improve the modeling. Additional continuously recording gages have been added within the Monument in order to better characterize the flood levels as a function of time.
The stage-storage relationship in a swamp is much more difficult to define than in a typical channel or reservoir. Major influences from groundwater and local rainfall occur. Hydraulic information from an upstream location near Columbia, South Carolina was modified using statistically derived relationships to predict the lag time and flood peaks at a gage within the Monument. Initial results showed an excellent predictive relationship between flood peaks between two stations, but the lag time showed little correlation. Future results will be provided in tabular and graphical forms so that Monument personnel can utilize them in making decisions about park utilization and in responding to visitor questions. As hydrologic modeling improves, the results will provide inputs for use in geographical information systems that may show flood levels on a real time basis.
SIGNIFICANCE
The Monument, part of the National Park system, provides educational opportunities for visitors and necessitates concern and provision for visitor safety. Of particular interest is information about the timing, extent, and duration of flood inundation. The project seeks to define this information for a number of locations so that Monument personnel can make informed decisions about park usage before and after flood events.