Effects of Urbanization on a Small Rural Watershed
Rasmussen, Walter L.
University of Wisconsin-Stevens Point, College of Natural Resources
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The Moses Creek Watershed, northeast of Stevens Point, Wisconsin, although quite small, has the potential for substantial downstream impact. The creek drains directly into the storm sewer system for the City of Stevens Point. The storm sewers are unable to handle the increased flow when flood potential is reached in the spring, and after heavy summer rains. At this time there are few buffers to ease the threat of flooding caused by Moses Creek; first, as it enters Stevens Point and second, as it enters the storm sewer system. Possible solutions to abate flooding within Stevens Point would be protection of the headwaters of Moses Creek and restoration of wetlands within the watershed. This study of Moses Creek will; gather stream flow and precipitation data for the watershed, generate a database using appropriate software, evaluate hydrologic modeling programs to determine the one best suited for Moses Creek, calibrate that model to provide a realistic representation of the watershed, and use the model to simulate potential future effects on the Moses Creek Watershed. Precipitation and stream flow data were analyzed to determine the hydrologic characteristics of the Moses Creek Watershed. These data were used to calibrate a runoff model, the United States Army Corps of Engineers, Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS). Environmental Systems Research Institute (ESRI) Arc View®, a software mapping tool using landuse, elevation, roads, soils, and property boundaries, facilitates definition of watershed hydrologic parameters and allows these parameters to be incorporated into HEC-HMS. The HEC-HMS model has shown a high degree of correlation between measured and modeled runoff. Agreement between measured and modeled data make it possible to manipulate parameters of the modeled watershed to evaluate the impact of land use changes in the actual watershed. Model runs reveal that the Moses Creek Watershed is sensitive and variable to subtle changes in characteristics of the watershed including precipitation, vegetation, soil saturation, pervious cover or lack of it. Subtle character changes have dramatic influence on downstream discharge volumes, duration of peak discharge and lag time between rainfall event and flood event.