When this option is selected a window will pop up showing the order of the reaches for computations (see Figure 5-91). The reaches are listed from upstream to downstream order. For complex models the reach order is very important. The HEC-RAS software will automatically compute the order for computations. However, the user can change the order if they do not like the order that the program came up with. Warning: changing the computational order for reaches can cause the computational programs not to work correctly. Before changing the computational order, be sure you fully understand what the steady flow and unsteady flow computational modules require for computational orders.

Figure 5 91. HEC-RAS Reach Computational Order Table