HR: 0800h
AN: H41A-0129    [Abstracts]
TI: Using Two-Year Recurrence-Period Discharge to Develop Regional Hydraulic Geometry Curves
AU: * Wilkerson, G V
EM: gw1@uiuc.edu
AF: University of Illinois at Urbana-Champaign Dept. Civil and Enviro. Engr., 2524 Hydrosystems Laboratory, MC-250, 205 N. Matthews Ave., Champaign, IL 61801, United States
AB: Knowledge of bankfull discharge, Q_bf, and channel characteristics (i.e., width, W_bf, depth, D_bf, and cross-section area, A_bf) is essential for planners, engineers, geomorphologists, environmentalists, agricultural interests, developments situated on flood prone lands, surface mining and reclamation activities, and others interested in floods and flooding. In conjunction with estimating Q_bf, W_bf, D_bf, and A_bf, regionalized hydraulic geometry relationships, which relate Q_bf, W_bf, D_bf, and A_bf to drainage basin area ( A_da), are often used. The utility of regional curves is due to the ease with which A_da can be obtained for any geographic location. Among other things, regional curves are useful for identifying and confirming field indicators of bankfull discharge and channel characteristics, stream assessments, and planning studies. This study seeks to improve upon the common practice of predicting Q_bf, W_bf, D_bf, and A_bf using A_da exclusively. Specifically, we hypothesize that predictions of Q_bf, W_bf, D_bf, and A_bf can be improved by including estimates of the two-year recurrence-period discharge ( Q₂) in regression models for predicting Q_bf, W_bf, D_bf, and A_bf. For testing this hypothesis, we use Q_bf, W_bf, D_bf, and A_bf measurements from 30 reports containing data for streams that span 34 hydrologically homogeneous regions in 16 states. Corresponding values of Q₂ were compiled from flood-frequency reports prepared in accordance with guidelines for conducting flood-frequency studies developed by the Interagency Advisory Committee on Water Data. By comparing statistical measures (i.e., root mean squared error, coefficient of determination, and Akaike's information criterion) we determined that predicting Q_bf from Q₂ rather than A_da yields consistently better estimates of Q_bf. Also, preliminary analyses to determine if using Q₂ improves predictions of W_bf, D_bf, and A_bf are promising. Other principal findings are (1) data are needed for at least 12 sites in a region for reliable hydraulic geometry model selection and (2) an approximate range of values for Q₂/ Q_bf is 0.10-3.0.
DE: 1821 Floods
DE: 1825 Geomorphology: fluvial (1625)
DE: 1856 River channels (0483, 0744)
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting