Fully two-dimensional (2D) models have been widely used for modeling river and coastal hydraulics and recently have become a viable practical option for modeling urban floods. As a stormwater management tool, 2D models are more accurate and produce results that are far more readily accepted and understood by managers, decision makers, and other stakeholders.
The application has incorporated a 2D hydrodynamic simulation engine into a user-friendly graphical interface which walks you through preprocessing of input data, calculation of the model, and displaying model results.
In this tutorial, a 2D component is added to one-dimensional (1D) river model developed in the previous tutorial. 2D objects are added as polylines and polygons. 2D job control parameters are set and the model is solved. Animations of velocity and water depth are displayed.
Define the 2D GRID extents:
|A 2D model can include multiple Grid Extents (Domains). The 2D domain(s) should not extend beyond the area covered by the DTM (1D domain or network can extend even beyond DTM).|
In the Manning's Roughness section, click the Constant radio button and set roughness to 0.05.
|Note that you can have variable Manning’s roughness values in the databases. If you click the Variable roughness radio button, you can enter the Depth vs Roughness values for the database. This is a useful tool for entering the roughness of natural streams which are essentially variable with the depth of flow.|
Click OK twice to return to the network view.
Right-click the Inactive 2D Area layer and select Import from GIS File option.
Browse for the file 2D_Inactive_Area.shp, select Open, and Import.
Click OK to return to the network view.
|By setting the 2D Head Boundary at an elevation below the grid cell elevations, this boundary will operate as a free outfall.|
|Note that the inflow hydrograph is already defined in the Node 1. Hence you do not need to define another 2D flow boundary.|
Right-click the 2D Vectors Max Velocity layer and select Properties from the menu.
Click the Arrow tab.
In the Arrow Head section, set to Fixed Size and enter Length to 3, and Width to 2.
In the Total Length section, set to Fixed Size and enter 10 as the scale factor. Set the Skip to 2 results.
Right-click the 2D Maps > Max Water Depth layer and select Properties from the menu.
Click the Fill Colors tab.
Adjust the Transparency to allow for better map display and then click OK.
Click the Play button to display the animation of velocity and water depth during the simulation period.
At what time does the stream flow over its banks?
Refer to the Common 2D Modelling Errors to help resolve issues that may arise during the 2D modelling process.