Boy, it's been so many years since I last did this that I've forgotten how it's done. Given that I know the length and width of an open channel, the volumetric flow rate of water through it and the inlet and outlet widths, how do I calculate to what depth the water will rise? The water is flowing by gravity alone and the hydraulic gradient is zero i.e. the invert levels at the inlet and outlet ends of the channel are the same. And no, I can't remember where my old school textbook is, otherwise I wouldn't be asking for help here.
Thanks everyone.