A river link is a reach, that is to say a part of a branch, or a point where the runoff from the catchment is distributed to the river. The spatial extent of the river link therefore controls how the runoff from the rainfall-runoff simulation is used in the hydrodynamic simulation.
River links may be added or deleted using the Append ‘+’ or Delete ‘-’ buttons above the overview table.
Note: The runoff related to a river link does not necessarily have to be the full runoff from a given catchment. A river link can therefore deal with only a part of a catchment’s runoff, for example when the total runoff has to be distributed through multiple river links.
A river link is defined with the two following groups of parameters.
The parameters below control the runoff value which is considered as part of the link.
· Catchment name. The catchment from which the runoff is computed is selected from this list.
· Linked area type. This parameter controls whether the part of the catchment used for the river link is expressed as an absolute area or as a fraction of the total area.
· Linked area. When the Linked area type is set to Linked area, this parameter indicates the area of the catchment which is considered for the river link. The resulting runoff for this river link will be the total catchment’s runoff multiplied by a ratio of the specified area with the total catchment’s area.
· Linked fraction. When the Linked area type is set to Linked fraction, this parameter indicates the fraction of the catchment which is considered for the river link. The resulting runoff for this river link will be the total catchment's runoff multiplied by the fraction. A fraction of 1 hence indicates that the total catchment's runoff is used.
The parameters below control where the runoff is applied to the river network for the hydrodynamic simulation.
· Distribute to. When distributing to a branch, the catchment runoff is distributed along a river branch. Alternatively, the runoff may be distributed to a storage.
· Branch name. The branch where the runoff is applied is selected from this list.
· Link type. Three link types can be selected:
- – Point: the specified runoff is added as a point source in the branch. This source is defined with a single chainage.
- – Distributed: the specified runoff is distributed to a reach along the branch. The location of the reach is defined with an upstream and a downstream chainage.
- – Entire branch: the specified runoff is distributed to the whole branch, hence no chainages have to be specified.
· Upstream chainage. For a Point link type, this chainage defines the location of the point source where the runoff is applied. For a Distributed link type, this chainage defines the upstream extent of the reach where the runoff is applied.
· Downstream chainage. For a Distributed link type, this chainage defines the downstream extent of the reach where the runoff is applied.
· Storage ID. Name of the storage in which the catchment runoff is inserted, when the river link is applied to a storage.
