Equation Quick ListFlow ThroughSuggested Equation(Ac-Ft)*(0.01676)=CFS or (Ac-Ft)*(7.54)=GPM When to use:Flow through can only be permitted using the SW-1 and SW-2 forms and are used to supply off channel reservoirs with the use of fish with oxygenated water.How to use:You will need the capacity of the reservoir in acre-feet. On Channel Reservoir CapacitySuggested Equation(Area*Depth)/3=Capacity When to use:Use this formula to calculate the capacity of a reservoir located in the channel of a water way when filing an SW-3 or SW-4.How to use:Calculate the area of the reservoir in acres Use the maximum depth of water in feet The results will be in acre-feet Pit Reservoir Capacity FormulaSuggested Equation((D/6)(area of top + area of bottom + 4* average area))/43560=Capacity in acre-feet When to use:Use this formula when applying for a reservoir on either SW-3 or SW-4 form and no water is to be stored above ground or against a berm.How to use:D is the maximum depth of the pit Area of the top for a rectangular reservoir is length multiplied by the width Area of bottom for a rectangular reservoir is the length multiplied by the width Average area is the area of the top plus the area of the bottom divided by 2 Pump FormulaSuggested EquationQ=HP(3960E)/T.D.H. When to use: When using a pump to apply water to lands using an SW-1 or SW-2 application not covered under Special Applications filings rules. If the filing falls in the category of Special Application the maximum amount of water that can be diverted is 0.056 Cubic Feet Per Second.How to use:HP is the horsepower of the pump which is typically found on the pump T.D.H. is the total dynamic head (Total dynamic head includes the friction in the pipe as well as the lift it has to make. The friction in the pipe will vary by type of pipe used.) E is the efficiency of the pump Q is the discharge flow rate Flow Rate DitchesSuggested Equation ManningsQ=(1.486AR^0.667S^.5)/n When to use:Use this formula for open channel earthen ditches filed for on an SW-1 or SW-2 formHow to use:Q is the discharge flow rate A is the area of the channel R is the hydraulic radius, which is the area divided by the wetted perimeter S is the slope n is the Manning’s number Gravity Flow PipelineSuggested Equations either Hazen-Williams or WeirsHazen-Williams Q=VA Q=A*(1.318*C)*(R^063)*(S^0.54) Weirs Q=CLH^(3/2) When to use:Use either of these equations for filing SW-1 or SW-2 forms for gravity and pressure flow pipelinesHow to use:Q is the discharge flow rate V is the velocity A is the Area C is the Hazen-Williams Coefficient R is the hydraulic radius S is the slope C is the coefficient of discharge L is the length of the crest in feet H is the feet of head |