Subject: Storage Volume vs Depth Equation in SWMM 5
A storage node in SWMM 5 can have either a functional form or a tabular depth/area table. The area functional form of a storage node is:
Area = A * Depth^B + C and the Volume has the form in node.c of the SWMM 5 of
Volume = A/(B+1)*Depth^(1+B) + C*Depth
For example if C is 25 square meters, A is 20 and the exponent B is 0.5 we get the following values for area and volume and you can also plot a Scatter Plot of Volume vs Depth in SWMM 5 (Figure 1).
|
Depth |
Area |
Volume |
|
Meters |
M^2 |
M^3 |
|
0 |
0.00 |
0.00 |
|
1 |
45.00 |
38.33 |
|
2 |
78.28 |
87.71 |
|
3 |
109.64 |
144.28 |
|
4 |
140.00 |
206.67 |
|
5 |
169.72 |
274.07 |
|
6 |
198.99 |
345.96 |
|
7 |
227.92 |
421.94 |
|
8 |
256.57 |
501.70 |
|
9 |
285.00 |
585.00 |
|
10 |
313.25 |
671.64 |
|
11 |
341.33 |
761.44 |
|
12 |
369.28 |
854.26 |
Table 1. Area and Volume for a Storage Node in SWMM 5.
Figure 1. You can use a Scatter Graph in SWMM 5 to show the relationship between Volume and Depth.