Hydrograph Pre-Developed Chart 1

[KevinW922]

I have been given a storm water project and am having some difficulty with the hydrographs and the material in it. I cannot find the relation to the volume calculations or how they arrived at the answers they did. Why V1 and V2? Can someone please help me understand?

 

[zelgar]

Well numerically,
V1 = delta t x q (e.g., (0.73 - 0)(0.65) = 0.47, (1.70 - 0.73)(1.94) = 1.88, etc.)
V2 = | delta t x delta q /2 | (e.g., |(0.73 - 0)(0.65 - 0)/2| = 0.24, |1.70 - 0.73)(1.94 - 0.65)/2| = 0.63)