ABSTRACT

Small tidal creek estuaries provide important ecological habitats that are increasingly under pressure from urban expansion. In south-eastern North Carolina these coastal counties are among the fastest growing counties in the state. In New Hanover County alone, urbanized land use has increased by 100% between 1976 and 1999. This urbanization has led to an encroachment and loss of these valuable resources. To study the impacts of urbanization, five tidal creeks were analyzed for land use characteristics and phosphorus compounds in sediments. The goals of this study were: a) identify the land use characteristics of the five tidal creek watersheds within New Hanover County; b) compare and contrast these watershed land use characteristics with concentrations of phosphorus measured from sediment samples taken at various locations within these watersheds; and c) perform a spatial sensitivity analysis of the contributing area to these sample locations to determine the relationships between land use and concentrations of inorganic phosphorus. The tidal influences and minimal topographic relief within these watersheds made it impossible to accurately map the drainage area for each sampling site and therefore a spatial sensitivity analysis method was developed to analyze the land use adjacent to each sampling site. The land use potentially contributing to each sampling site was calculated using three radius measurements (0.25, 0.5, and 0.75 mile). Results indicate that the there is no significant statistical relationship between the various types of land use development (e.g. commercial, industrial, transportation, etc.) and the percentage of inorganic phosphorus in the tidal creeks. In comparing simply developed versus undeveloped land, there is a nonlinear relationship between the percentage of developed land and the percentage of inorganic phosphorus. In comparing the buffer sizes, the level of geographic analysis is most closely related to the percent inorganic phosphorus at the 0.25 and 0.5 mile radii and less at 0.75 mile radius. Results from this study illustrate the usefulness for careful geographic scrutiny and robust spatial analysis.

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