The CWD uses the following terms:
Features of the Constructed Waterway Designer:
Because in reality the Main/Low Flow Channel (M/LFC) can have a flatter grade than the Main Waterway (due to sinuosity of the M/LFC within the Main Waterway) the CWD can use one grade for the M/LFC and another for the Main Waterway, within the same cross-section.
The CWD uses the M/LFC grade to determine the dimensions required for the M/LFC to carry its required discharge (e.g. a 3 month or 1 year discharge) and then uses the Main Waterway grade to determine the dimensions required for the Main Waterway to carry its discharge (e.g. a discharge having an Annual Exceedance Probability of 1%).
The shear stresses on the cross-section can be checked from the Constructed Waterways Designer, and if they are too high, new batter slopes, bench widths etc. can be tried.
The total width of the cross-section can be checked so that you know whether the current design fits in the available space.
The freeboard can be varied (normally either 600mm or 300mm).
Each Segment of the cross-section can have its own Manning's n value.
Once the input data has been entered you can check the shear stresses from the CWD screen (see next page) then return to this screen to make any adjustments necessary.