DiverHyd can be used to simulate diversion channels and multi-outlet structures. By entering a table of inflow-outflow relationships the hydrologic object can split a hydrograph into a maximum number of five hydrographs. The five hydrographs must add up to the original inflow hydrographs.
The inflow-outflow relationship is defined with FLOW TABLE. As shown in Table 3 9, maximum 20 values can be defined for the inflow and each outflow. All outflows should add up to the total inflow.
TABLE 3-9 DIVERHYD FLOW TABLE
| Total Inflow | 1st Outflow | 2nd Outflow | 3rd Outflow | 4th Outflow | 5th Outflow |
|---|---|---|---|---|---|
| QTOTAL (1) | Q1(1) | Q2(1) | Q3(1) | Q4(1) | Q5(1) |
| QTOTAL (2) | Q1(2) | Q2(2) | Q3(2) | Q4(2) | Q5(2) |
| … | … | … | … | … | … |
| QTOTAL (20) | Q1(20) | Q2(20) | Q3(20) | Q4(20) | Q5(20) |
When the program runs simulation for DivertHyd, it will divide the inflow at DivertHyd by following rules:
1. If there is only one row in the flow table, the diversion ratio of each downstream hydrograph is the division flow in the flow table divided by the total flow in the flow table. In other words, the first downstream hydrograph is Q1out = Q1(1) / QTOTAL (1) x Qinf, etc., where Q1out is the divided flow of the first downstream hydrograph and Qinf is the DivertHyd total inflow.
2. If there are multiple rows, the program will compare the DivertHyd inflow with the total flow defined in the each row of the flow table. If the DivertHyd inflow is larger than the total flow of row J (i.e. QTOTAL (J)) and smaller or equal to the total flow of row (J+1) (i.e. QTOTAL (J+1)). The flow will do interpolation between those two rows. In other words, Qkout = (Qk(J+1) – Qk(J)) / (QTOTAL (J+1) – QTOTAL (J)) x (Qinf – QTOTAL (J)) + Qk(J)
