HR: 1340h
AN: H43D-1613    [Abstracts]
TI: A Case Study of Differing Effects of Urbanization on Streamflow From Two Proximate Watersheds
AU: * Brandes, D
EM: brandesd@lafayette.edu
AF: Dept of Civil & Environmental Engineering, Acopian Engineering Center Lafayette College, Easton, PA 18042, United States
AU: Lott, F
EM: lottf@u.washington.edu
AF: Civil & Environmental Engineering, University of Washington, Seattle, WA 98195, United States
AB: The effects of urbanization on streamflow from two proximate watersheds (Little Lehigh Creek (LLC) and Monocacy Creek (MC)) are investigated. Despite close similarities in rainfall, population growth, land use, imperviousness, and geology of the watersheds, streamflows at the LLC gage have changed markedly over the past 50 years, while those at the MC gage have not. In LLC, there are significant increasing trends in annual stormflow volume, annual maximum flow, and flashiness, but there are no significant trends in these measures in MC. Neither stream shows significant trends in annual baseflow volume or low flow. It appears that the distinct difference in response to urbanization of these two streams can be ascribed to differences in 1) watershed geomorphology, 2) spatial distribution, composition, and infiltration characteristics of carbonate bedrock, and 3) the spatial pattern of land development in each watershed with respect to the gage location. In regards to geomorphology, there is a steeper main channel and narrower floodplains in LLC than in MC. Carbonate soil and bedrock (primarily dolostone) are distributed throughout much of LLC watershed but only in the lower half of MC watershed; however the lower MC watershed (primarily limestone) has much more abundant sinkholes and karst features than in the LLC watershed. Finally, residential and commercial development is concentrated in the upper two thirds of the LLC watershed, where travel times are such that these areas contribute to the peak flows measured at the gage. Development is concentrated in the lower third of the MC watershed, where it has had less effect on peak flows at the gage. Overall, the study indicates that relatively subtle differences between watershed characteristics and development patterns can result in significant differences in runoff and in how streamflow regimes may change in response to urbanization.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1819 Geographic Information Systems (GIS)
DE: 1872 Time series analysis (3270, 4277, 4475)
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting