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Add an Instream Flow Reach

The following approach assumes that the added instream flow is a “future” structure and not an actual instream flow with a valid model identifier (WDID) in HydroBase. If the added structure is in HydroBase, create the input files without set commands first and identify missing information prior to setting input data.

  1. Open the network (*.net) in StateDMI, navigate to the appropriate location, and right-click to Add an Upstream Location. Enter the appropriate information and designate the structure type as an instream flow node. If the instream flow is a reach, also add a downstream node and designate the structure type as an Other node.
    • Downstream nodes are typically named with the instream flow ID and _Dwn suffix.
    • Note if an instream flow is added as a headwater node, it must be made a baseflow node and have a natural flow distribution.
  2. Recreate the river network file (*.rin) to reflect the additional structure(s).
  3. Add the structure to the instream flow station file (*.ifs) using the StateDMI commands:
    • Set the ID of the upstream and downstream nodes that define the reach; or set the same ID as the upstream and downstream nodes to reflect a point.
    • Indicate whether a variable (*.ifm) or constant (*.ifa) demand will be provided.
  4. Add water rights to the instream right file (*.ifr) using the StateDMI commands:
    • Set the water right ID as the structure ID with a numeric suffix for each right.
    • Set the water right priority (administration number) and amount in CFS.
  5. Add the structure’s demand to the instream flow demand file (*.ifa or *.ifm) using the TSTool commands.
    • Set the monthly instream flow demands or read in an external StateMod formatted file (*.stm) with the demand in CFS .
  6. Confirm the revised diversion files (*.ifs, *.ifr, *.ifa/m) are reflected in the response file (*.rsp).
  7. Simulate the model.
  8. Review the instream reach output file (*.xir) for data on the minimum instream diversion and the diversion at every point within the instream flow reach.
    • When modeled as a reach, the information in the diversion summary output file (*.xdd) represents the minimum amount diverted by the instream flow within the reach. Therefore one may notice the water available in the river exceeds the amount diverted.