The software will on occasion display the channel status as critical flow at certain channel slopes. This occurs when the software switches the hydraulic calculation method due to the complex nature of the calculation.
Critical flow does not mean that the channel system is failing. It is recommended when designing a system with critical flow to not use the features ‘Optimise by Section’ or ‘Optimise Per 1m’. Instead it is recommended to manually test each channel size by pressing the button ‘Remove Optimisation’ located in the ‘Channel Design’ section of the main screen. Once activated the channel size can be chosen within the ‘Channel size’ section of the main screen.