loss coefficients

[warrow17]

hi..pls help..
i used EPANET to simulate the flow of water through a chamber which has four sluice gates in it. there are no flor meters inside the chamber so there is no way of measuring the water level. i used an fcv to represent the sluice gate. i varied the loss coefficient of the valve to simulate the changes in the gate setting of the sluice. but is there a formula that directly relates the gate opening of the vale to its loss coefficient?
thank you.