Source allows the user to conveniently create the catchment model though through Geographic Wizard conveniently. However, before Before Source version 4.10.0 - Beta Release (August 2019), however, the user cannot was not able to change the created sub-catchment boundary such as merging i.e. merge sub-catchments after Geographic Wizard creates created the scenario. The new function was developed to merge sub-catchments and reset relevant model elements (such as network/link) and attributes (such as rainfall runoff model parameters) in an existing catchment model. The developed function has been included in the Source software tool since the version 4.10.0 – Beta Release.
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First of all, the user needs a Source project with a geographic scenario and to open the project.
Combine Catchments At Selected Node Boundaries:
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The procedure to combine catchments At selected node boundaries is illustrated as follows:
- Click on a single node from the interface to select this node, such as the confluence circled in orange cycled on Figure 1 (i.e. Node on catchment SC#10 in this example).
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- Right click on the interface’s empty space (that this can keep the node selected) to pop up open the Geographic Editor.
- Click on Combine catchments >> At selected node boundaries to display the interface windows of Combine Catchments as demonstrated in Figure 2. At the beginning, the contests under Catchment Group is empty.
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- To Primary catchment: The property of this sub-catchment will be retained for the combined catchment such as the parameters of rainfall runoff and other models. In this example, the primary catchment is SC#13. The selected node is the single outlet of the combined catchment.
- Absorbing Catchments: Sub-catchment listed under Catchment (i.e. SC #21, SC #12, SC #20 in this example) will be merged with SC #13 and their properties will be discarded.
- Assign primary: This button allows the user to change the primary catchment if the user wants to use the a property from another sub-catchment for the combined catchment. The user can click on any sub-catchments listed under Catchment, then click on Assign primary. The selected sub-catchment (SC #12 in this example) will be displayed intoas Primary catchment, and the previous primary catchment will be moved to the absorbing catchments.
- Network Restructure:
Collapse to primary catchment node – Ticking this function will lead a network with the link from the primary catchment to the outlet. Otherwise, the networks and nodes from all absorbed catchments will be kept as it is.
Absorb upstream boundary nodes- This function allows to remove all nodes in absorb absorbed catchments and it is enabled only when Collapse to primary catchment is ticked.
- Clear groups to re-configure boundaries button will clean the found sub-catchments and reset the interface as Figure 2.
- Combine button will close Combine Catchments Interface; combine the catchments upstream of the selected node , and reset the network and nodes accordingly.
- Cancel button will close Combine Catchments Interface without any combination action.
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This method allows the user to manually to select the sub-catchments to combine.
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- Manually select the sub-catchments (use the Zoom option to Zoom in to the sub-catchments, and keep Selected Catchments in Layer Manager ticked) as demonstrated in Figure 4.
Figure 4. Manually select sub-catchments for combining catchments
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Figure 7. The result catchment combined from manually selected sub-catchments
- The associated properties properties are changed correspondingly For example, the new rainfall and runoff table table (Figure 8) shows the sub-catchments #12, #SC 20 and #21 was removed, and the combined catchment inherited the property from SC# 13, the primary catchment, such as ID, parameters.
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