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online_wsprofiles_32:   H2 water-surface profile DESCRIPTION
General

• The php script [program]   online_wsprofiles_32   calculates an H2 water-surface profile in a prismatic open channel using the direct-step method (Chow, V. T.: Open-channel hydraulics, McGraw-Hill, 1959).

• If requested by the user, the program calculates critical depth at the downstream boundary [default value] based on the geometric and hydraulic input data. Newton's iteration is used to solve the nonlinear equations.

• An H2 profile is supernormal, subcritical, and the bottom slope is horizontal (see figure). The calculated gradually varied flow depth varies between the specified flow depth at the downstream boundary [or, if requested, the calculated critical depth] and the specified flow depth upstream [headwater depth].

Input

• There are four required input variables:   discharge Q, bottom width B, side slope z, and Manning's n.

• For the downstream boundary condition, you can specify a suitable input flow depth. Alternatively, if the input flow depth box is left blank, the program will use critical depth instead.

• For the upstream boundary condition, you must specify a suitable upstream flow depth [headwater depth].

• By convention, the flow direction is assumed to be from left to right, as shown in the figure. Therefore, the input upstream flow depth must be greater than the input [or calculated critical] downstream flow depth.

• The program echoes the input data. Internally calculated critical depth is echoed with five-decimal (5) accuracy.

Defaults

• For the input flow depth, you can enter any suitable subcritical supernormal flow depth. The allowable range of input flow depth is the following: Greater than [or equal to] critical depth, and less than [input] upstream flow depth. Leave this box blank if you want the program to use critical depth.

• You can enter the desired number of computational intervals n. The suggested range is 50-200. A higher number means higher computational accuracy. Leave this box blank if you want the program to set the default value at 100.

• You can enter the desired number of tabular output intervals m. The suggested range is 10-100. A higher number means more detailed [longer] output. Leave this box blank if you want the program to set the default value at 10.

Output

• A table with thirteen (13) columns: output interval index k, [flow] depth (m), [flow] area (m2), velocity (m/s), velocity head (m), specific head (m), wetted perimeter (m), hydraulic radius (m), friction slope (m/m), average [friction] slope (m/m), specific head difference (m), length increment (m), and total [channel] length (m).

• The number of computational intervals n and the number of tabular output intervals m are printed for reference.

Units

• The current version is written in SI [metric] units.

Errors

• Enter only positive [nonzero] numbers for discharge. Failure to do this will trigger an error message and halt execution (Error message No. 1).

• Enter only nonnegative [zero or greater] numbers for bottom width and side slope. Failure to do this will trigger an error message and halt execution (Error messages No. 2: A and B, respectively).

• Bottom width and side slope cannot be zero at the same time. Failure to do this will trigger an error message and halt execution (Error message No. 3).

• A Manning's n value outside of the range 0.008-0.250 will trigger an error message and halt execution (Error message No. 4).

• An input downstream flow depth less than the calculated critical depth will trigger an error message and halt execution (Error message No. 5).

• An input downstream flow depth greater than or equal to the input upstream flow depth [minus a tolerance of 0.001 m] will trigger an error message and halt execution (Error message No. 6).

• An input upstream flow depth less than or equal to the input (or calculated) downstream flow depth [plus a tolerance of 0.001 m] will trigger an error message and halt execution (Error message No. 7).

Thank you for running online_wsprofiles_32.   Please call again.   [Version 1.0.0,   070509]