Linking river networks with 2D domains

Integration of river networks and 2D components allows (for example) water overtopping a river bank to flow onto the floodplain.

Your river network should be completely defined beforehand, and run to successful completion in a 1D only simulation. This 1D only simulation may require a higher “glass wall” to account for there not being anyway for overtopping flows to go to - ensure this is changed back for the integrated simulation.

To integrate a river network and 2D components, you must first create the so-called "link-lines" to indicate which nodes are connected, and how the flow is transferred at each. You can Select the link-lines to use from 3 available types.

The link-lines are polyline shapefiles with specific attributes. Flood Modeller provides a specific tool to help with creating link-lines. You can Use the link-line generator to draw these link-lines directly onto the Map view. The tool also automates the process of filling in the Required link-line attributes.

Alternatively you can Create link-lines manually using specific tools. In this case you will also need to Add attributes to the shapefiles manually.

Useful tip: Data is required wherever a river node is connected to the 2D domain, however these connections can all be contained in single link-line file. The linking shape file can contain multiple lines (features), where each line represents a separate link specified between two adjacent 1D nodes. Hydraulic data will pass between the 1D and 2D solvers at the start and end of a link line (which are referenced to 1D nodes) and then the 2D engine will interpolate conditions between these points along the length of each link.Alternatively, you can define multiple link lines each in separate shapefiles and include all of these files in your 2D model setup.

After defining the link-lines, you need to Configure the 2D simulation window to setup an integrated simulation. This needs to specify your link-lines file, alongside your 1D river simulation and 2D components.

Useful tip: Test running the 2D only component individually using the link line shapefile as the boundary and assign a constant flow. This will allow you to check how stable these aspects are prior to integrating with the river network.

Ensure you save your simulation to keep any changes. Your integrated simulation is now ready to run. This is run in exactly the same way as when you Run a 2D simulation.

The above method is suitable for using the ADI or TVD solvers, however it is also possible to Create a 1D River - FAST linked simulation.

If you encounter issues with your integrated simulation, exploring the Diagnostics and Tips will help identify problems and resolve warnings and errors.

Alongside the multiple options provided for viewing 1D and 2D results, Integrated Modelling Results include the data passed across the linked aspects as an additional output.