STEP A: First, input and store values for K:

.xxx

Enter value for S

x

Square root of S

x 1.486

Times constant of 1.486

= 1/x

Calculate and invert denominator

x .xxx

Times value for n

= STO or M+

Store constant K

STEP B: To calculate R for various values of V:

RCL or MRC

Recall K

xV

Times value for velocity

=

Equals

Yx 1.5

Raise product to 3/2 power

=

Displays value for R

STEP C: Repeat Step B for different V values until you reach an acceptable R and Q.

STEP 6. Select the appropriate hydraulic radius from the appendix.

Use the ditch table, table 4-3, page 4-14. There are four types of tables; V symmetrical, V nonsymmetrical,

trapezoidal symmetrical, and trapezoidal nonsymmetrical, listed in FM 5-430-00-1/AFPAM 32-8013, Volume 1.

For this problem, use table 4-2, page 4-7.

Locate the columns representing the side slopes of the ditch being designed, for example, 3:1.

Locate the R values that fall above and below, or the one that is exactly equal to the R value found from the

nomograph of Manning's Equation. In the example, the values are 0.85 and 0.90. USE THE LOWER VALUE!

For example, use 0.85.

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