Peak Flow - Rational Method (Riverside County, S.
California)
This command is design to compute peak flow in the Riverside
County, southern California. In Riverside county as well as
Southern California, peak flow is calculated based on the Rational
method, Q = CIA, but it also has its own computing criteria because
of its extremely varied topography, soil types and land uses, and
its storm events that are different than other regions.
First, Riverside County usually requires a peak flow calculation on
10-year and 100 year storm events. So rainfall data of riverside
county should be defined in the rainfall library. We provide two
methods, Rainfall Accumulation and Rainfall Intensity, which allows
any combination of return periods of 2-year, 5-year, 10-year,
25-year, 50-year and 100-year rainfall definition. IDF curves would
be calculated. Second, Riverside County defines a list of land
development types, which affect the subarea runoff index and
percentage of the impervious cover, and therefore lead to the
calculation of the time of concentration, rainfall intensity,
runoff coefficient and then peak flow. The types of land
development are: Commercial, Apartment, Mobil home park,
Condominium, Single family(1/4 Acre lot, 1/2 Acre lot, 1 Acre lot),
Undeveloped with poor, fair or good cover. Please refer to the
Riverside County Hydrology Manual for details.
Select Rational Method (Riverside County) from Watershed > Peak
Flow menu. In the peak flow dialog, choose a rainfall from the
rainfall library, and specify the return period and the antecedent
moisture condition. The spreadsheet displays the list of drainage
area data in design. Add Drainage Area button allows you to add a
new drainage entry, Edit Drainage Area button allows you to edit
the highlighted entry and Remove Drainage Area button removes the
highlighted entry. When you add or edit a drainage area, the
Add/Edit Drainage Area dialog opens. Enter the drainage area name,
specify the soil type and cover type from a look up table, and
choose the land development type. The area can be entered either
manually or automatically by selecting a closed polyline from
screen. The flow line data can also be obtained from picking a 3D
polyline and the program calculates the length and slope of the
flow automatically. Click on OK button to commit the drainage area
entry.
The design data can be saved to a .riv file, and loaded back to the
dialog. Report button reports the design data and hydrology
calculation results. The Use Report Formatter option allows you to
report data to a spreadsheet instead.
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Peak Flow Dialog
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Add/Edit Drainage Area
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Prompts
Peak flow dialog: Fill in values
Pulldown Menu Location: Watershed -> Peak Flow >
Rational Method (Riverside County, S. California)
Keyboard Command: peakflw5
Prerequisite: