WMS:HEC-RAS Unsteady Modeling

This topic explains how to create and run an HEC-RAS unsteady model. The first step for creating an unsteady model is to setup and export an HEC-RAS hydraulic model in the usual way. After you exported your HEC-RAS model, perform the following steps to set up the unsteady model and post-process the solution inside of WMS:

1. Go to HEC-RAS and set up a steady state simulation that runs to completion.
2. After your steady state simulation is set up, you need to define the unsteady model. One of the main requirements of an unsteady model is to provide a hydrograph as a boundary condition for the unsteady model. You can obtain this hydrograph from one of the hydrologic models in WMS, from measured data, or from any other method. Enter this hydrograph as a boundary condition in HEC-RAS, eliminating any 0 values from the hydrograph.
3. Run the unsteady model, continuing to fix any errors until the model runs to completion. Save your HEC-RAS project and close HEC-RAS.
4. Go back to WMS and (from the river module) read the solution for the HEC-RAS project (.prj) file. All the time steps from the unsteady model will be read into WMS. To view the results of the unsteady simulation, you will now need to delineate the floodplain at each of these time steps. This can be done in the same way as delineating a floodplain from a steady state simulation.
5. Interpolate the water surface elevations in the 1D Hydraulic Centerline and the 1D Hydraulic Cross Section coverages. This will interpolate the water surface elevations at all time steps.
6. Delineate the floodplain. The floodplain will be delineated for all time steps.
7. Select the flood depth data set from the floodplain delineation. Set the contour options as desired and run a film loop on this data set.

Related Topic

• Hydraulic Modeling
• Export GIS File
• Read Solution
• Overview of Flood Plain Delineation
• Interpolate Results
• Delineate Flood Plain
• Setting up Film Loops