online_wsprofiles_21:   M1 water-surface profile Main page Example Summary Reference Disclaimer DESCRIPTION General The php script [program]   online_wsprofiles_21   calculates an M1 water-surface profile in a prismatic open channel using the direct-step method (Chow, V. T.: Open-channel hydraulics, McGraw-Hill, 1959). The program calculates normal depth based on the geometric and hydraulic input data. Newton's iteration is used to solve the nonlinear equations. An M1 profile is subnormal, subcritical, and mild (see figure). The calculated gradually varied flow depth varies between the specified flow depth at the downstream boundary and [it is asymptotic to] normal depth upstream. Input There are five required input variables:   discharge Q, bottom width B, side slope z, bottom slope So, 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 a value close to normal depth (1.01 * yn) instead. The program echoes the input data. Internally calculated normal depth is echoed with five-decimal (5) accuracy. Defaults For the input flow depth, you can enter any suitable [subcritical] subnormal flow depth, i.e., a flow depth greater than normal depth. Leave this box blank if you want the program to use a value close to normal depth (1.01 * yn) [In general, this option is not recommended, because the M1 profile would be very close to uniform flow]. 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. The calculated normal depth and normal-depth Froude number are printed for reference. If the normal-depth Froude number exceeds 0.99, execution is halted (see error message No. 7 below). Units The current version is written in SI [metric] units. Errors Enter only positive [nonzero] numbers for discharge, Manning's n, and bottom slope. Failure to do this will trigger an error message and halt execution (Error messages No. 1: A, B, and C, respectively). 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). A bottom slope outside of the range 0.000005-0.05 will trigger an error message and halt execution (Error message No. 5). An input flow depth less than or equal to the calculated normal depth will trigger an error message and halt execution (Error message No. 6). A normal-depth Froude number greater than 0.99 will trigger an error message and halt execution (Error message No. 7). Thank you for running online_wsprofiles_21.   Please call again.   [Version 1.0.0,   070430]