2006 BES Annual Meeting Presentation and Poster Abstracts
Pre-Restoration Geomorphic and Sediment Conditions of Minebank Run, Baltimore County, Maryland
Co-Authors: Edward J. Doheny, U.S. Geological Survey, and Paul M. Mayer, U.S. Environmental Protection Agency
Abstract: Urban streams frequently undergo severe incision and erosion due to flashy streamflows caused by impervious surfaces in the watershed. Such streamflows can lead to unstable sediment dynamics that can limit options for stream restoration. The U.S. Environmental Protection Agency, U.S. Geological Survey, and Baltimore County Department of Environmental Protection and Resource Management are collaborating to study the effects of restoration on sediment processes in a selected study reach of Minebank Run, a small urban stream in Baltimore County that is currently being restored. The pre-restoration dimension, pattern, and profile of the stream channel at Minebank Run were quantified, and changes over time caused by storms and flooding were assessed. Changes in cross- sectional area, bed elevation, lateral migration of the stream channel, rate of bank retreat, and grain- size distribution were measured throughout the study reach. Pre-restoration longitudinal-profile surveys indicated rapid and significant changes in the distribution of riffles, pools, and runs within the study reach, indicating continuous alteration of benthic habitat. Changes in channel-bed elevation indicated alternating periods of degradation and aggradation in different locations of the study reach. Boundary shear-stress computations showed erosive power nearly an order of magnitude larger than that of similar non-urban streams, suggesting that restoration of urban streams must address highly variable flow regimes to be successful. The Minebank Run stream channel was restored during 2004 and early 2005. Post-restoration characterization of sediment dynamics is planned to determine whether specific restoration techniques enhamce the stability of the dimension, pattern, and profile of the stream channel.