Handling of MODSIM-multilinks

[etrianaGIT]

The coupling code needs to handle for segments that are represented in MODSIM with multi-links. Potential issues are foreseen in the MODSIM-GSFLOW mapping table and also in the handling of flows for the GSFLOW segments. This potential issues was discovered in the Russian River network representation, but needs to be handled for the general implementation. The solution should include a check for total flow in the surface segment if it's passed or checked against the GSFLOW segment flows. It could also be an issue in diversion points because multiple water rights are usually simulated with multiple links that should be aggregated to pass to GSFLOW.

[emorway-usgs]

Let's consider making a variant of the Sagehen test model that has a multi-link for testing any modifications we make. We could make the diversion for the offline reservoir or the Demand node a multi-link, right? Perhaps a method for handling this can be worked out through information passed within the mapping_info table.

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