American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 395434 bytes)    Cited by

WATER RESOURCES RESEARCH, VOL. 41, W07009, doi:10.1029/2005WR004097, 2005

Effects of urban development in the Puget Lowland, Washington, on interannual streamflow patterns: Consequences for channel form and streambed disturbance

Christopher P. Konrad

U.S. Geological Survey, Tacoma, Washington, USA


Derek B. Booth

Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA


Stephen J. Burges

Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA


Abstract

Recovery and protection of streams in urban areas depend on a comprehensive understanding of how human activities affect stream ecosystems. The hydrologic effects of urban development and the consequences for stream channel form and streambed stability were examined in 16 streams in the Puget Lowland, Washington, using three streamflow metrics that integrate storm-scale effects of urban development over annual to decadal timescales: the fraction of time that streamflow exceeds the mean streamflow (TQmean), the coefficient of variation of annual maximum streamflow (CVAMF), and the fraction of time that streamflow exceeds the 0.5-year flood (T0.5). Urban streams had low interannual variability in annual maximum streamflow and brief duration of frequent high flows, as indicated by significant correlations between road density and both CVAMF and T0.5. The broader distribution of streamflow indicated by TQmean may be affected by urban development, but differences in TQmean between streams are also likely a result of other physiographic factors. The increase in the magnitude of frequent high flows due to urban development but not their cumulative duration has important consequences for channel form and bed stability in gravel bed streams because geomorphic equilibrium depends on moderate duration streamflow (e.g., exceeded 10% of the time). Streams with low values of TQmean and T0.5 are narrower than expected from hydraulic geometry. Dimensionless boundary shear stress (τ*) for the 0.5-year flood was inversely related to T0.5 among the streams, indicating frequent and extensive bed disturbance in streams with low values of T0.5. Although stream channels expand and the size of bed material increases in response to urban streamflow patterns, these adjustments may be insufficient to reestablish the disturbance regime in urban streams because of the differential increase in the magnitude of frequent high flows causing disturbance relative to any changes in longer duration, moderate flows that establish a stable channel.

Received 7 March 2005; accepted 13 April 2005; published 13 July 2005.

Keywords: streamflow statistics; fluvial geomorphology; hydraulic geometry; disturbance; urban streams; Washington.

Index Terms: 1860 Hydrology: Streamflow; 1825 Hydrology: Geomorphology: fluvial (1625); 1803 Hydrology: Anthropogenic effects (4802, 4902).

Read Full Article (file size: 395434 bytes)    Cited by

Citation: Konrad, C. P., D. B. Booth, and S. J. Burges (2005), Effects of urban development in the Puget Lowland, Washington, on interannual streamflow patterns: Consequences for channel form and streambed disturbance, Water Resour. Res., 41, W07009, doi:10.1029/2005WR004097.