Hydrology, Part 2 – Peak Flow For Ungaged Sites- 3 PDH
COURSE TITLE: HYDROLOGY, PART 2 – PEAK FLOW FOR UNGAGED SITES
This course will cover the concepts of how to estimate various return period peak flow values for locations that do not have nearby USGS stream gages. While various statistical analysis can be employed on streams that have USGS gages, established peak flow values for other locations is often necessary. Methods presented include regression approaches such as the USGS Regression Equations, USGS Urban Watershed Studies, and the USGS StreamStats software. The course also covers the SCS Graphical Peak Discharge Method and the Rational Method. The use of the Index Flood Method and Peak Discharge Envelope Curve are included.
The course will describe the factors that need to be determined in order to appropriately use the regression equations. It will also describe the basic use of the StreamStats software which allows for rapid calculation of all necessary regression equation parameters. The use of the SCS Graphical Peak Discharge Method will be described in detail, including examples. This course is based primarily on information from Federal Highway Administration publication HDS-2, Hydrology and the USGS StreamStats software.
• REGIONAL REGRESSION EQUATIONS
o Analysis Procedure
o USGS Regression Equations
▪ Hydrologic Flood Regions
▪ Assessing Prediction Accuracy
▪ Comparison with Gaged Estimates
▪ Application and Limitations
o USGS Urban Watershed Studies
▪ Peak Discharge Equations
▪ Basin Development Factor
▪ Effects of Future Urbanization
▪ Local Urban Equations
o FHWA Regression Equations
o USGS Streamstats Program
• SCS GRAPHICAL PEAK DISCHARGE METHOD
o Runoff Depth Estimation
o Soil Group Classification
o Cover Complex Classification
o Curve Number Tables
o Estimation of CN Values for Urban Land Uses
o Effect of Unconnected Impervious Area on Curve Numbers
o Ia/P Parameter
o Peak Discharge Estimation
• RATIONAL METHOD
o Estimating Input Requirements
o Check for Critical Design Condition
• INDEX FLOOD METHOD o Procedure for Analysis o Other Considerations
• PEAK DISCHARGE ENVELOPE CURVES
At the conclusion of this course, the user will:
• Understand how to use the USGS Regional Regression Equations
• Understand how the USGS StreamStats software can be used to obtain more accurate estimates of basin parameters and to estimate peak flows.
• Understand how to use the SCS Graphical Peak Discharge Method.
• Understand the factors involved in the use of the Rational Equation and how to estimate these factors and compute peak flows.
• Understand how the Index Flood Method and Peak Discharge Envelope Curves can be used to estimate peak flows.