Method: Camp’s critical velocity, Vetter’s efficiency equation and the DoED / Mosonyi / ITDG guidelines, as used in typical run-of-river headworks design. Fall velocity and sediment concentration are inputs you must justify from your own data. This is a preliminary-design aid; check the result against the governing guideline before using it for a real project.
The starting values are an illustrative example. A red check on them only means that example is marginal at that point; it is not an error in the tool.