Scientific Investigations Report 2009–5133
Regional hydraulic geometry curves are power-function equations that relate riffle dimensions and bankfull discharge
to drainage-basin size. They are defined by data collected through surveys conducted at stable stream reaches and can be
used to aid watershed managers, design engineers, and others involved in determination of the best course of action for an
unstable stream. Hydraulic geometry curves provide a mechanism through which comparisons can be made between riffle
dimensions collected at an unstable stream to those collected at stable streams within the same region. In 2005, a study
was initiated to delineate regional hydraulic geometry curves for Michigan. After
Regional hydraulic geometry curves were developed rather than statewide curves owing to large differences in factors that control channel geometry across the State. However, after the data were subdivided according to ecoregions, it was determined that there were enough data to delineate regional hydraulic geometry curves only for the Southern Lower Michigan Ecoregion. For this ecoregion, geometry curve equations and their coefficients of determination are:
Width = 8.19 x DA0.44; R2 = 0.69,
DA is the drainage area and
By use of discharge estimates for the Southern Lower Michigan Ecoregion, a bankfull discharge curve was delineated. The corresponding equation and its coefficient of determination are:
Discharge = 4.05 x DA0.95; R2 = 0.60.
Posted October 16, 2009
The above links are to electronic copies of Appendixes 1 through 3–2, which are referenced in the Contents section of the main report.
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Rachol, C.M., and Boley-Morse, Kristine, 2009, Estimated bankfull discharge for selected Michigan rivers and regional hydraulic geometry curves for estimating bankfull characteristics in southern Michigan rivers: U.S. Geological Survey Scientific Investigations Report 2009–5133, 300 p.
Bankfull Discharge Comparison to Flood-Frequency Statistics
Regional Hydraulic Geometry Curves
Summary and Conclusions
Appendix 1. Longitudinal-profile survey data
Appendix 2–1. Riffle cross-section survey data used for regional curve development and bankfull discharge estimation
Appendix 2–2. Ancillary riffle cross-section survey data
Appendix 3–1. Riffle pebble-count data
Appendix 3–2. Reach average pebble-count data