Tuflow and estry manual Version 3

3.17.5.2Linking ISIS 1D Domains

TUFLOW 2D domains can also be dynamically linked to ISIS 1D domains. The ISIS software must be installed and configured to support the linking to TUFLOW.

The linking approach is very similar to linking to ESTRY. A 1d_x1d GIS layer showing the locations of the ISIS 1D nodes must be created. This layer requires only one attribute, namely a string 12 characters long that contains the unique IDs of the ISIS 1D nodes. Any other attributes are presently ignored. Creation of this layer may be possible through exporting from ISIS a text or csv file containing the Node ID and XY coordinates of the nodes provided the coordinates are in the same projection as the 2D domain(s).

In the .tcf file, specify the following command to read the 1d_x1d layer:

Read MI ISIS Nodes == ..\model\mi\1d_x1d_isis_nodes.mif

Connections (CN) in the 2d_bc layer are snapped to the nodes in the 1d_x1d layer in the same manner as if connecting to a 1d_nwk layer. The 1d_x1d layer can contain ISIS nodes that are not connected to a 2D domain.

There are presently limitations when connecting to ISIS nodes as follows:

• 
  HX lines should only be connected to ISIS RIVER units. This requires that the ISIS unit between consecutive connections along a HX line is always a RIVER unit. If this is not the case, an “ERROR - 2D HX cell has been assigned to a non-RIVER unit” occurs. Where a non-RIVER unit occurs (eg. at a structure), the HX line needs to be broken.
  
• 
  Along a HX line, all ISIS RIVER unit nodes between the upstream and downstream ends of the HX line must be connected (unlike ESTRY where a node can be intentionally or accidentally omitted). If an ISIS node is not connected an “ERROR - Cannot determine upstream ISIS unit node for 2D HX cell” occurs.
  
• 
  Special ISIS units maybe required for some HX and SX connections (refer to the ISIS documentation).
  

The same checks that the ZC elevation of a HX cell lies above the bed of the 1D nodes and that the ZC elevation of a SX cell lies below the 1D node bed are made, and if not, an error occurs.

Use the new 2d_x1d_check.mif file to crosscheck the ISIS nodes that were read and associated information passed from ISIS. Also use the 1d_to_2d_check.mif file to crosscheck which HX and SX cells are connected to which ISIS nodes.

Note that the start and end simulation times and the timestep are controlled by the ISIS inputs fields, therefore, any Start Time, End Time and Timestep commands are ignored in the .tcf file.

No .ecf file is required and the ESTRY Control File command should not be specified unless there are also ESTRY 1D domains in addition to the ISIS 1D domains.



Figure 4.11 Examples of 2D HX Links to 1D Nodes