This is a handy app for calculating flow and pressure. The user can set different shapes for the channel, such as circular, square, triangle, and trapezoid. It also supports different sizes, such as small, medium, and large. The calculation is based on the well-known Manning equation. 

The app has a short explanation behind the equation, as well as a table with all the required values. The user can also choose different parameters to be calculated, such as the flow rate, the channel size, and the slope of the water surface.

The app can be used for any kind of calculation, such as for school projects or personal use.