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| A topologic tree can be used to create a watershed configuration in the absence of digital terrain or feature object data (the only possibility for the public domain version of WMS). The tree representation can then be used to select basins and outlet points for entry of all basin and routing data, in the same way the digital terrain based watershed map can be used. Geometric parameters such as areas, lengths, and slopes, which can be automatically computed when a digital terrain model is used, must be entered interactively. However, all other features of the hydrologic modeling interfaces work in the same fashion.
| | #REDIRECT [[WMS:Topologic Trees]] |
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| All of the functions for building and/or editing trees (except diversions and reservoirs) cannot be used when a digital terrain model is used. In this case, all new basins and outlet points must be created from the digital terrain model.
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| ==Adding Commands==
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| ===Adding Basins===
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| The '''Add | Basin''' command of the '''Tree''' menu defines a new drainage basin for the selected outlet point. Any number of sub basins can be associated with each outlet point. Typically, there are either one or two (a sub basin for each upstream branch), depending on whether or not the outlet point represents a branch in a stream network.
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| ===Adding Outlets===
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| The '''Add | Outlet''' command of the '''Tree''' menu allows the user to enter a new outlet "upstream" from the currently selected outlet node. This represents a new confluence or sub-basin outlet which is upstream from the selected outlet. In this fashion, a network of outlet points can be built which actually represent the stream network of the watershed.
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| ===Adding Reservoirs===
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| A reservoir can be created for an outlet by selecting the outlet and choosing the '''Add | Reservoir''' command from the '''Tree''' menu. By creating a reservoir at an outlet storage, routing for the outlet can be done followed by routing from the outlet of the reservoir to the next downstream outlet point.
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| ===Adding Diversions===
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| Diversions are defined in a two step process: by defining the diversion at the outlet or basin where flow is to be diverted, and then assigning a previously defined diversion (retrieving a diversion) to another outlet. Diversions are defined by first selecting an outlet point or a drainage basin where the flow is diverted and then selecting the '''Add | Diversion''' command from the '''Tree''' menu.
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| After adding a diversion, a link will be drawn from the outlet or basin selected to the side of the Graphics Window, indicating that no retrieval outlet has yet been specified for that diversion.
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| The retrieval outlet point can be specified when defining diversions from one outlet to another by multi-selecting the retrieval outlet before issuing the Add Diversion command.
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| ===Adding Sources===
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| The '''Add | Source''' command of the '''Tree''' menu allows the user to define a source at an "upstream" outlet. No basins or outlets may exist upstream from a source outlet as they are intended to represent the headwaters of a stream within a basin and the source is that flow entering the modeled watershed through the stream.
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| ===Adding Sinks===
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| The '''Add | Sinks''' command of the '''Tree''' menu allows the user to define a sink at a "downstream" outlet. No outlets may exist downstream from a sink outlet as they are intended to represent the discharge of a stream within a basin and the sink is that flow leaving the modeled watershed through the stream.
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| ==Deleting==
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| ===Deleting Basins===
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| The '''Delete | Basin''' command of the '''Tree''' menu can be used to delete a selected drainage basin from a given outlet. The Select Drainage Basin tool should be active to select a basin icon.
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| ===Deleting Outlets===
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| The '''Delete | Outlet''' command of the '''Tree''' menu allows the user to delete selected outlet points. The Select Vertices tool can be used to select outlet points which are to be deleted.
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| ===Deleting Reservoirs (Tree)===
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| The '''Delete | Reservoir''' command of the '''Tree''' menu can be used to delete a selected reservoir from a given outlet. The Select Outlets tool should be active to select an outlet icon where a reservoir has been defined from the Tree menu.
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| ===Deleting Diversions===
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| The '''Delete | Diversion''' command of the '''Tree''' menu can be used to delete a selected diversion. The Select Diversions tool should be active to select a diversion icon.
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| ===Deleting Sources===
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| The '''Delete | Sources''' command of the '''Tree''' menu is used to delete a defined source from an outlet.
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| ===Deleting Sinks===
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| The '''Delete | Sinks''' command of the '''Tree''' menu is used to delete a defined sink from an outlet.
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| ==Inserting Outlets==
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| The '''Insert Outlet''' command of the '''Tree''' menu allows the user to enter a new outlet between two selected outlet points. This makes it possible to insert a confluence which may have been inadvertently left out or to simply subdivide a watershed into smaller sub basins. The Insert Outlet command can also be used to insert a new outlet at the base of a tree. In such cases then only the bottom most outlet should be selected before issuing the Insert Outlet command.
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| ==Retrieving Diversions==
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| To retrieve a diversion at an outlet point, select the outlet point where the diverted flow is to be retrieved and then select the '''Retrieve Diversion''' command from the '''Tree''' menu. If more than one diversion not yet retrieved exists, a list of defined diversions without retrieval outlet points (a diversion cannot be assigned to more than one retrieval outlet) will appear in the diversion selection dialog. Select the name of the desired diversion and choose OK.
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| After retrieving a diversion, the diversion link will now be drawn from the outflow outlet or basin to the retrieval outlet point. HEC-1 only allows inflow to be defined at outlet points.
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| ==Topologic Trees==
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| A topological tree is one way to represent a watershed in the absence of terrain data. When a digital terrain model or feature objects are being used to automate basin delineation and build a particular sub basin configuration, a tree is simultaneously generated. The tree representation uses icons for confluences (outlet points) and basins, and should be clear to both experienced and inexperienced users of hydrologic models such as HEC-1 or TR-20.
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| The public domain version supports the building of a hydrologic model using a topologic tree as the only means of developing the model.
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| An equivalent tree representation is also shown and can be selected from the Project Explorer.
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| ==Related Topics==
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| * [[WMS:Hydrologic Modeling Tools|Tool Palette]]
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| {{WMSMain}}
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