When setting up a Orange County Rational Method simulation, data must be entered for each sub-area.
Area: The sub-area area (acres or ha.) can be automatically computed when using a DEM or TIN
% Nonmountainous and % Mountainous: The percentage of the sub-area that lies below and above 2000 ft, respectively. Use the Compute % Mountainous button to calculate these values using a DEM or TIN.
Initial Sub-area
Tc: The time of concentration (min)
Intensity: The rainfall intensity (in/hr) is automatically computed based on the Tc
ap: Pervious area percentage
Fp: Pervious area loss rate
Fm: Maximum area loss rate
Calculate Fm by toggling on the Compute Fm checkbox, entering values for ap and Fp, and using the Compute Fm button or click on the Compute Fm - GIS button to use GIS data.
Related Topics:
Losses
Initial Sub-area Time of Concentration
Orange County Rational Equation
Orange County Rational Method
Reach Routing
Creating Watershed Models