Document Type

Thesis

Abstract

Development alters runoff from the land surface and changes stream flow and stream water chemistry. Documenting and quantifying these impacts and their causes can aid in making decisions regarding the extent of development and the reduction of its impacts. Previous studies have shown that peak flow and runoff coefficients increase and lag time decreases as the area of impervious land increases. Increases in phosphates, nitrates, and conductivity are also associated with increased development. In this study we investigate how the extent of development influences stream hydrology in Williamsburg, VA. We focus on analyzing peak flow and lag time in response to storms, changes in baseflow during low-flow periods, and changes in water chemistry brought on by development. Gaging stations were installed on three streams with the extent of basin development varying from ~15% to ~65% and basin area ranging from ~1km* to ~1.5 km’. Lag time is ~2 hours longer in the less developed basin where decreased impervious ground results in slower runoff pathways. Peak discharge was greater by up to an order of magnitude in the developed streams mainly in larger storms. It is not clear why this relationship is not applicable for storms of all sizes. While it has been hypothesized that differences in baseflow might be a contributing factor, the data does not consistently support this hypothesis. Nitrate, ammonium, phosphate, and conductivity concentrations are highest in the developed basins and lowest in the undeveloped basin. The results of this work indicate that development is having an effect on stream flow and water chemistry in Williamsburg.

Date Awarded

2002

Department

Geology

Advisor 1

Gregory S. Hancock

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