Thesis for Master of Science (Civil Engineering), 1996


Quantification of Surface Hydrology Effects for Eastern North Carolina Forested Wetlands

Ellen Kay Stone

(under the direction of H. Rooney Malcom, Civil Engineering)


Abstract

An important factor in creating or restoring wetlands is hydrology. The primary focus of this study is to quantify surface hydrology effects for specific plant communities as defined by the North Carolina Heritage Program in order to develop reference wetlands for wetland mitigation projects. Average maximum stage of inundation events, percentage of inundation, and consecutive submerged and unsubmerged days were examined to determine their relationship to each community type and specific tree species. A secondary focus of this study is to determine a reliable way to estimate average daily stage.

Consecutive submerged events greater than eight days were more similar within community groups than submerged events less than eight days and average maximum depths of submerged events. This applied to both growing and dormant seasons. The tree species Acer rubrum, Liquidambar styraciflua, Fraxinus pennsylvanica, and Quercus 1aurifolia were predominately correlated with submerged events between five and eight days and average maximum depths of submerged events occurring in the growing and dormant seasons. Drainage area is correlated with the presence of Liquidambar styraciflua and Fraxinus pennsylvanica.

The average daily stage at a study site may be estimated using USGS gaging station data, Manning equation, and regression analysis between a short-term recorder and a long-term gaging station. Regression analysis is the most reliable in any situation. USGS gaging station data is more effective for sites within 500 feet of the gaging station, but can be used less effectively for longer distances. Manning equation is fairly reliable if a roughness coefficient greater than 0.09 is used.