ElizaCollison: Created page with " =Introduction= In this section we create the 1D channels. For this tutorial a number of completed channels are provided as a guide. If this was not provided, the method woul..."

2023-01-06T05:50:32Z

Created page with " =Introduction= In this section we create the 1D channels. For this tutorial a number of completed channels are provided as a guide. If this was not provided, the method woul..."

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=Introduction=
In this section we create the 1D channels. For this tutorial a number of completed channels are provided as a guide. If this was not provided, the method would be to import the "1d_nwk_empty.mif" file from the TUFLOW\model\mi\empty folder and save this in the TUFLOW\model\mi directory and begin the edits in this layer.
=Method=
<ol>
<li>Ensure the cross-section layer is open.</li>
<li>Copy the '''1d_nwk_M04_channels_001''' and '''1d_nwk_M04_Culverts_001''' files from the '''Module_Data\Module_04\''' folder and into the '''TUFLOW\model\mi\''' folder you are working in. Open the both files in MapInfo.</li>
<li>Add these layer to the map window and make the '''1d_nwk_M04_channels_001''' layer editable.</li>
'''TIP:''' To avoid editing or snapping to the previous version it is recommended that you close the '''1d_nwk_M02_culverts_001.tab''' version, if it is open. 
<li>In order to make the snapping to the cross-sections easier make the vertices on the cross sections visible. To do this right click on the layer in the layer control window and select "properties", in the
window select '''Show Node'''. Showing nodes was used [[Tute_M01_Boundaries_MI_Archive |in module 1]] to snap the external boundary.</li>
<li>Ensure that snapping is enabled by toggling the "S" key.</li>
<li>Zoom in to the south western edge of the model, where the main inflow occurs.</li>
<li>Digitise a polyline from the end of the channel provided, along the creek centreline, and double click on a vertex of the next cross-section downstream to finish the channel segment. Each channel (from cross-section to cross-section) is required to be a separate line object. Don't fill in the GIS attributes yet, we will fill these out at the end.
'''Tip:''' Using a line style with an arrow at the end of the line makes it easy to see where one channel ends and the next begins.</li>

[[File:Tute M04 MI 1d nwk 01.jpg|500px]]
 
<li>At the location of the 1st culvert (in the '''1d_nwk_M04_culverts_001''') we need to ensure that the channel snaps to the layer upstream of the culvert. At the downstream end of the culvert, ensure that start of the open channel is snapped to the end of the culvert. In these locations there are three layers snapped together: the culvert, channel and cross-section.</li>
[[File:Tute M04 MI 1d nwk 02.jpg|500px]]
 
<li> The first two sections downstream of the channel have been digitised in the layer provided. In this area there is an alternative flow path over a meander in the channel. A weir channel has been digitised in the layer provided. We need to connect this up to the main channel. Digitise a line from the junction of the channels to the upstream end of the weir, as shown in the image below. 
</li>
[[File:Tute M04 MI 1d nwk 03.jpg|500px]]
 
<li>Enter '''"X"''' into the GIS attribute '''Channel_Type'''. This "X", or channel connector, connects the channels together but indicates that the weir is not the main channel path. 
</li>
[[File:Tute M04 MI 1d nwk 04.jpg|500px]]
 
<li>At the downstream of the weir, enter another channel connector. 
</li>
[[File:Tute M04 MI 1d nwk 05.jpg|600px]]
 
<li>Continue digitising channels between the cross-sections. At the second culvert, ensure you snap to each end of the culvert. At the downtstream of the model, snap to the channel provided in the layer. 
</li>
[[File:Tute M04 MI 1d nwk 06.jpg|800px]]
 
<li>Once all the the channel lines have been drawn we will update the GIS attributes. The first thing we need to do is select only the channels that do not have any properties set. The channels provided as part of the module data already have the correct attributes. To select the channels without a '''Channel Type''' assigned, we will use the select function in MapInfo. To access this select ''Query >> Select'' from the menu.</li>
<li>Select '''1d_nwk_M04_chanel_001''' from the drop down dialogue. Select ''Assist'' and then enter the search query as <tt>Channel_Type=""</tt>. Press Ok to complete the selection.</li>
[[File:Tute M04 MI 1d nwk 07.jpg|frame|none]]
 
<li>This should open a new browser window with the newly created items.</li>

[[File:Tute M04 MI 1d nwk 08.jpg|600px]]
 
<li>We can now update this selection. To do this select ''Table >> Update Column'' from the menu items. In the update dialogue set the ''Table to Update'' to the last item, this is the newly created selection. If no other queries have been performed this will be called '''Query1'''. Set the ''Column to Update'' to '''Channel_Type'''. In the ''Value'' option set this to "S". Uncheck the ''Browse Results'' tick box (if you leave this checked a new browser window will be opened as ''Query2''. 
This step has updated all channels not yet assigned as the "S" type, which is the standard type of open channel.

</li>

[[File:Tute M04 MI 1d nwk 09.jpg|600px]]
 
[[File:Tute M04 MI 1d nwk 10.jpg|600px]]
 
<li>Repeat the update process to update the ''Use_Chan_Storage_at_Nodes'' to "T". This tells TUFLOW to automatically calculate the storage at the nodes (ends of the channel) based on the cross-sectional properties and the channel length.</li>
<li>Update the ''Mannings_n'' to 0.09 (don't use quotes because this is a numerical field). Set the ''Upstream_Invert'' and ''Downstream_Invert'' to -99999.</li>
<li>To avoid assigning a channel name to each of these channels we will also use the update function to do this automatically. Use the process above to update the ''ID'' column of the query table. In the ''Value'' enter <tt>"FC1_"+format$(rowid,"000")</tt>. This includes the creek ID - FC1 and then adds a unique row number. As these were digitised from upstream to downstream, this value should be in increasing order from upstream to downstream.</li>
[[File:Tute M04 MI 1d nwk 11.jpg|500px]]
 
[[File:Tute M04 MI 1d nwk 12.jpg]]
 
<li>Save the '''1d_nwk_M04_channels_001''' file and export to .mif format for import into TUFLOW.</li>
The open channel is now ready for input into TUFLOW. In Tutorial Module 2 we created a number of 1D/2D links for the culverts. We did this in a number of ways, one of these was to create the link using a 1d_nwk layer[[Tute_M02_MI_1d2d_Link_Archive#1d_nwk_link | (link to Module 2)]]. Now that we are modelling the entire creek in 1D we need to remove these. The 1D open channel and the 1D culverts are connected already based on their snapping. To remove the 1D/2D connections for the culverts, please follow the steps below:
<li>Make the '''1d_nwk_M04_culverts_001''' editable. </li>
<li>Select the nodes at the upstream and downstream of the culvert and delete these. 
'''Before deletion'''
 
[[File:Tute M04 MI 1d nwk 13.jpg]]
 
'''After deletion'''
 
[[File:Tute M04 MI 1d nwk 14.jpg]]
 
<li>Save the '''1d_nwk_M04_culverts_001''' file and export to .mif format for import into TUFLOW.</li>
</ol>
=Conclusion=
The 1D network layers are now ready for input into TUFLOW. Please return to the tutorial where the next step is to [[Tutorial_Module04_Archive#1D.2F2D_Links | define the 1d/2d connections]].

Tute M04 MI 1d nwk Archive - Revision history

ElizaCollison: Created page with " =Introduction= In this section we create the 1D channels. For this tutorial a number of completed channels are provided as a guide. If this was not provided, the method woul..."