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Hydraulics Design Manual -01

The Hydraulics Design Manual, or HDM, provides policies, practices and procedures used by the Oregon Department of Transportation for the hydraulic design of highway facilities.

The HDM presents engineering information based on established ODOT practices for highway drainage projects. Sound engineering judgment remains a vital part in the process of applying the design criteria in this manual to individual projects.

Appendix A - Rainfall Intensity - Duration - Recurrence Interval Curves  

       Plate 1 - Rainfall IDR Curve Zone  

       Plate 1a - Rainfall IDR Curve Zone with mile points 


Appendix B - U.S. Geological Survey Regression Equations for Rural Western Oregon 

Appendix C - U.S. Geological Survey Regression Equations for Urban and Rural Eastern Oregon  

Appendix D - U.S. Geological Survey Regression Equations for Arid Regions of Rural Eastern Oregon 

       Plate 1 - Northwest Flood Region Boundary   

       Plate 2 - Mean Annual Precipitation in Eastern Oregon  


Appendix E - U.S. Geological Survey Nationwide Urban Regression Equations  

Appendix F - Rational Method 

Appendix G - Natural Resources Conservation Service Unit Hydrograph Method  

       Oregon Engineering Handbook  
       Urban Hydrology for Small Watersheds 

 Appendix H - Oregon 24-hour Precipitation Maps  ​
       Plate 1 - 2-year, 24-hour

       Plate 2 - 10-year, 24-hour​

       Plate 3 - 25-year, 24-hour

       Plate 4 - 50-year, 24-hour

       Plate 5 - 100-year, 24-hour​

       Plate 6 - 500-year, 24-hour

       Plate 7 - 1,000-year, 24-hour​ 


Appendix I - 2-year, 7-Consecutive Day Low Flows 

        Plate 1 - Boundary Between Western and Eastern Oregon

        Plate 2 - Normal Annual Precipitation 1930-1957 State  of Oregon

        Plate 3 - Mean Minimum Temperature, January in Western Oregon

        Table 1 - 2-year, 7-Consecutivie Day Low Flow Discharges for Western Oregon

        Table 2 - 2-year, 7-Consecutive Day Low Flow Discharges for Eastern Oregon

        Appendix J - Mean Daily Exceedance Discharges

        Appendix K - Maximum Predicted Discharge Based on Station Records and Envelope Curve

Contact the Hydraulics Engineering Program

4040 Fairview Industrial Drive SE, MS 5

Salem, Oregon 97302