A simulation of a spillway and stilling basin using Excel spreadsheet

The behavior of water flow through a rectangular open channel spillway with a stilling basin and step was analyzed using Excel and Visual Basic for Applications. All the parameters of the flow (such as critical flow, depths at key points, lengths of different segments) were calculated given a set of parameters. For the initial stilling basin design, the Froude number at the beginning of the jump and the length of the stilling basin after the jump were set. Also it was assumed that the flow will become "uniform" after the step. Given these parameters a flow profile was derived. To test the design for various conditions, the flow was decreased while the channel dimensions (such as total length of the spillway, step size) were left the same as the initial design to simulate seasonal flow changes. Then the new flow profile and Froude number at the beginning of the jump were determined as functions of flow rate.