You can use either the Average End Area or the Conic Approximation method, or both, to calculate volumes for the stage storage table.
Average End Area Method
The Average End Area method calculates the volume between two cross sections; the cross-sectional areas are averaged and multiplied by the distance between cross sections to determine the volume.
The Average End Area method is expressed by the following equation:
where V is the volume, calculated from the two end areas, A1 and A2, and the distance L between the two areas.
Conic Approximation Method
The Conic Approximation method calculates the volume between two sectional areas; the two areas being added along with the square root of their product and multiplied by a third of distance between the areas to determine the volume.
The Conic Approximation method is expressed by the following equation:
where V is the volume, calculated from the two areas, A1 and A2, and the distance h between the two areas.