Some time ago I created a user-defined function for use in Excel® to solve the Colebrook-White / Darcy-Weisbach flow equations for an elliptical pipe. Given the flow, the two semi-axes of the ellipse, the pipe slope, the C-W roughness and the liquid's kinematic viscosity, this function returns the flow depth (plus a few other related properties). You could use this to develop a spreadsheet to do the calculations. If this is the sort of thing you are after, post your e-mail address and I'll send it to you (with the usual disclaimers applying, of course).