1D-2D Flood Modeller-TUFLOW: Difference between revisions

The digitised direction of the HX and CN lines is not important. The CN lines however should be digitised approximately perpendicular to the direction of flow. Two CN lines are digitised for each node and snapped to the HX boundary lines along the left and right banks at vertices. Both CN and HX lines are digitised within the same 2d_bc file, on a basic approach, you only need to input the '''type''' attribute (either '''CN''' or '''HX'''). It is also recommended to input an '''f''' attribute value of '''1''' for CN lines for clarity, however if left at zero TUFLOW will by default change this value to 1. There are a range of Flags that can be used within the 2d_bc file, also D values to change elevations of the link cells and also A values to change the storage across the cells. Further information on these can be found within the <u>[https://docs.tuflow.com/classic-hpc/manual/latest/ TUFLOW manualManual]</u>.

Flood Modeller can also be dynamically linked to outflow directly to the 2D TUFLOW domain at the start or end of a Flood Modeller reach. This can relate to tributary channels, small drainingdrainage channels, and also the main channel if exiting into a 2D estuarine environment for example.

The image below shows the representation within Flood Modeller and TUFLOW of a simple flume model. As you can see in Flood Modeller, the end open channel section '''FMT_003''' links directly to a spill unit, housing the same cross-section data, which then links to a dummy HT boundary unit. This dummy unit is left empty and works as a link between Flood Modeller and TUFLOW. TakingTo connect the Flood Modeller schematisation1D acrossnetwork to TUFLOW, assimilar we saw into the section above, the open channel section is linked via a 1D node and 2d_bc CN/HX connection. The SX link comes into play by having another 1D node (which, for clarity, it is recommended having a separate file to the Flood Modeller Nodes) which has the same ID as the dummy HT boundary. Remember that Flood Modeller is case sensitive so name exactly as is in Flood Modeller. As the connection between the open channel section '''FMT_003''' and the dummy boundary happens in Flood Modeller, no literal link is needed between these in the TUFLOW GIS files. All that is needed otherwise is a 2d_bc file with a CN/SX link snapped to the dummy boundary node, this again can be in a separate file to the CN/HX links for clarity or can be in the same file.

As with all aspects of TUFLOW modelling, checking your files are being applied as intended is important. The check file to use in the case of 1D 2D linking is of course the 1d_2d_check. TheIn the image below you can see the channel being modelled, and the Flood Modeller nodes connected via a CN/HX link discussed earlier. The 1d_2d_check file is shown by the blue grid cells. This shows the user the cells being picked up by the HX link lines, it also housesprovides a wealth of information such as the primary Flood Modeller node it links to and if any flags where used in the HX lines for example. Below wethe areimage showingshows the elevation picked up at each link cell, thiswhich can be extremely useful in finding any abnormally low cells that have perhaps been incorrectly picked up and are subsequently leading to out of bank flow which in reality wouldn't beoccur therein reality.

1D Flood Modeller and 2D TUFLOW models can be dynamically coupled to enable a bi-directional connection between the two software using either HX or SX links. The linkage take place when an Flood Modeller node is snapped to a HX or SX boundary, this can be via a CN connection link. The dynamic coupling allows full integration between Flood Modeller 1D networks and full floodplain modelling in TUFLOW 2D to capture complex overland flows.