HR: 14:10h
AN: H53D-03    [Abstracts]
TI: Bed Mobility and Channel Morphology Complexity in Urban and Rural Stream Channels
AU: * Prestegaard, K L
EM: kpresto@geol.umd.edu
AF: Dept. of Geology, University of Maryland, College Park, MD 20742 United States
AU: Boyle, P
AF: Dept. of Geology, University of Maryland, College Park, MD 20742 United States
AB: Stream morphology, which includes channel width, depth, grain size,grain arrangement, bank morphology, etc. varies over short distances along a stream. Many natural channels are quite complex and exhibit significant variability in channel characteristics. An effect of increased runoff in urbanized areas is to enhance stream bank and bed erosion, which may decrease channel morphological variability. The purpose of this study is to determine whether urban stream channel morphology is significantly less complex than non-urbanized streams in the same region. Stream reaches were chosen in 20 urbanized and 40 non-urbanized watersheds in Maryland, Wisconsin, and Washington. Watershed areas ranged from 2 to 30 km2. Channel morphological characteristics were measured at intervals spaced 1 channel width along the channel over reaches that 14-20 channel widths in length. Bankfull channel and grain size characteristics were used to determine local bed mobility at each site within each reach. The non-urbanized watershed data were used to determine: a) variations in channel morphology complexity with stream size (watershed area), b) variations in channel morphology complexity with bed mobility, and c) how to characterize channel morphological complexity over a reach. Channel morphological complexity showed an inverse correlation with bed mobility in both urban and non-urban channels. Channel morphology complexity did decrease with the amount of urbanization in the watershed if the critical dimensionless shear stress was significantly exceeded at bankfull stage.
DE: 1803 Anthropogenic effects
DE: 1824 Geomorphology (1625)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting