Various types of drainage facilities are required to protect the highway against surface and subsurface water. Drainage facilities must be designed to convey the water across, along, or away from the highway in the most economical, efficient, and safe manner without damaging the highway or adjacent property. The purpose of this manual is to provide detailed information on the subjects of hydrologic and hydraulic analysis related to highway design. This manual should be used in conjunction with the Washington State Department of Transportation (WSDOT) Highway Runoff Manual and the WSDOT Design Manual, specifically Section 1210.
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 »
After the appropriate storm frequency for the design has been determined (see Chapter 1) and the time of concentration has
Time of concentration (Tc) is defined as the time for runoff to travel from the hydraulically most distant point of
The runoff coefficient “C” represents the percentage of rainfall that becomes runoff. The Rational Method implies that this ratio is
2-6 Rational Method This section presents a description of the Rational Method. 2-6.1 General The Rational Method is used to
Regardless of snowmelt impacting a project site, PEOs should consider the following issues to provide adequate road drainage and prevent
When the project is listed as a mountainous route, per the WSDOT Highway Log, or is over an elevation of
Snowmelt and rain on snow is a complicated process and can result in greater runoff rates. There are two parts
To determine the basin area, use the StreamStats web application, quadrangle maps, or ArcMap/GIS Workbench. These tools cannot be used