Design Storm Hyetograph
The SBUH Method requires the input of a rainfall distribution or a design storm hyetograph. The design storm hyetograph is […]
Single-Event Hydrograph Method: Santa Barbara Urban Hydrograph
The SBUH Method is best suited for WSDOT projects where conveyance systems are being designed and for some stormwater treatment
Single-Event Hydrograph Method: Santa Barbara Urban Hydrograph Read Post »
Rainfall Intensity
After the appropriate storm frequency for the design has been determined (see Chapter 1) and the time of concentration has
Time of Concentration
Time of concentration (Tc) is defined as the time for runoff to travel from the hydraulically most distant point of
Runoff Coefficients
The runoff coefficient “C” represents the percentage of rainfall that becomes runoff. The Rational Method implies that this ratio is
Rational Method
2-6 Rational Method This section presents a description of the Rational Method. 2-6.1 General The Rational Method is used to
Additional Considerations
Regardless of snowmelt impacting a project site, PEOs should consider the following issues to provide adequate road drainage and prevent
Calculating Snowmelt
When the project is listed as a mountainous route, per the WSDOT Highway Log, or is over an elevation of
Cold Climate Considerations
Snowmelt and rain on snow is a complicated process and can result in greater runoff rates. There are two parts