ChannelFlow: Qcia

This is a basic implementation of the Rational Method. The graphical check provided from the "view" button in the program shows the area as a bar graph, with acres incremented, and the color faded out in relation to the "C" value. Please note that this line will make use of the IDF Curve file name, or constant, given for the table.

Input Parameters:
name Text of up to 10 characters. Blanks are not allowed. This is in order to preserve the tabular printout, which can be read back into the program.
A Drainage or watershed area. VSMH section 4-4.1.2 limits this to 20 acres. Lindeburg references areas up to "several hundred acres or so" (p.6-13)
C Rational coefficient. Suggested values from the VSMH, Table 4-3:
Land Use C Land Use C
Business, Ind. or Com. 0.9 Res. 10,000sf lots 0.5
Apts. 0.75 Res. 12000sf to 17000sf lots 0.45
Schools 0.6 Res. >=0.5acre lots 0.5
park, unimproved areas 0.34 forest 0.3
paved and roof areas 0.9 grass slopes (2:1) 0.7
cultivated areas 0.6 shoulder and ditch 0.5
pasture 0.45 lawn 0.2
+CA# This is a value to add to the computed CA for this line. (It is not the computed CA for this line.) Another "Qcia" row can be referenced, and it will add the CA value from that row.
+CA# Same as above.
tc Time of concentration. If this value is left zero, an intensity, "I", value must be given. If a value for "tc" is given, the IDF Curve file for the table will be used to compute the intensity.
I The intensity of rainfall. This can come from this input space, or the IDF curve file given (if a "tc" value is input), or from a constant value given in place of the IDF Curve file name.
Output:
sum CA The sum of computed and additional or given CA values.
I This is a computed intensity value interpreted from the IDF Curve, if a tc value and an IDF curve were given.
Q The peak flow.

Of course, the Rational method is: flow, Q = CIA.

(return)