1D Culverts: Difference between revisions
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=Introduction=
A culvert is a structure that allows water to flow under a road, embankment, railway or other similar obstruction from one side to the other. Culverts or pipe channels can be either rectangular, circular (pipe) or irregular in shape and can vary in size depending on the flow and design requirements.
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=1D-2D Connections=
Connection of a 1D drainage network to the 2D domain typical occurs using one of the following features: <br>
*1D inlet pits (more details can be found [[1D_Pits | here]]).
*Manually assigned 2D SX connections
Information on how to create a 1D-2D connection in a GIS package are explained within <u>[[Tutorial_M03 | Tutorial 3]]</u>.
===SX Connection Hints===
To limit the doubling up of expansion and contraction losses on a culvert (as 1D nwke culverts will already contain height, width, entry and exit coefficients) the 2D flow into and out of a culvert should be as representative of the culvert dimensions. You can achieve this by selecting the number of 2D cells that best matches the width/diameter of your particular culvert. The example below shows a 4m culvert that has used an SX line to select 2 x 2m grid cells to discharge to. Remember that the selection of a particular cell, when using a polyline, requires the polyline intersect the cell cross-hair - refer to the <u>[https://docs.tuflow.com/classic-hpc/manual/latest/ TUFLOW Manual]</u>. <br>
[[File:Culvert_SX_connection_1.JPG|border|500px]]
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Standard SX connections on the 1D network to the 2D domain where the terrain surface (cell elevations) is greater than the 1D node level will result in an <font color="red"><tt>Error 2050</tt></font><tt>.</tt> Details about this error can be found [[TUFLOW_Message_2050 | here]].<br>
<div><ul>
<li style="display: inline-block;"> [[File:SX_connection_1.JPG|thumb|none|800px|2D SX connection]] </li>
<li style="display: inline-block;"> [[File:SX_connection_1LS.JPG|thumb|none|700px|2D SX connection - Section view]] </li>
</ul></div>
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Including a "Z" flag will only lower the selected 1D-2D cell. The level of water within the hole will need to increase above the surrounding surface before it will flow into the 2D domain. Using the "Z" can lead to instability issues so it is important to ensure the DTM modification is appropriate in your model. Details about this warning can be found [[TUFLOW_Message_2118 | here]].<br>
<div><ul>
<li style="display: inline-block;"> [[File:SX_connection_2.JPG|thumb|none|800px|2D SX connection with "Z" flag]] </li>
<li style="display: inline-block;"> [[File:SX_connection_2LS.JPG|thumb|none|700px|2D SX connection with "Z" flag - Section view]] </li>
</ul></div>
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Including a Zline or Zshape that modifies the surrounding topography removes any warning or error, in this particular case the Zline also creates a smooth transition for water to flow from the culvert. No need for a "Z" is required.
<div><ul>
<li style="display: inline-block;"> [[File:SX_connection_3.JPG|thumb|none|800px|2D SX connection with Zline]] </li>
<li style="display: inline-block;"> [[File:SX_connection_3LS.JPG|thumb|none|700px|2D SX connection with Zline - Section view]] </li>
</ul></div>
=Flow Regimes=
The flow regime through a culvert are divided into the following types. Checking this information for any 1D culvert can be inspected from the _TSF.mif/_TSF_P.shp that outputs the regime at each output interval. <br>
{| align="left" class="wikitable
! style="background-color:#005581; font-weight:bold; color:white;"| Regime
Line 45 ⟶ 64:
|}
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'''Example of the _TSF results in GIS:'''<br>
[[File:TSF_result_file.JPG|border|600px]]
Line 52 ⟶ 70:
The GIS results for the _TSF layer show the flow regime that was recorded at each output interval.
=Modelling Bend Losses=
Where bends occur within one culverted length, additional losses can be applied using the form_loss attribute of the 1d_nwk layer. This applies the energy loss appropriately for a 'minor' loss using K*V<sup>2</sup>/2g. Bend loss coefficients (K) are found in many standard hydraulic references, e.g.:
=Typical check files used=▼
The table below highlights some of the commonly used check files when reviewing 1D culverts. The full list of TUFLOW check files can be found [[TUFLOW_Check_Files | here]]. <br>▼
:*<u>[https://www.business.qld.gov.au/industries/mining-energy-water/water/industry-infrastructure/supply-planning/urban-stormwater-drainage Queensland Urban Drainage Manual]</u>
{| align="center" class="wikitable" width="75%"▼
:*<u>[https://www.ciria.org/CIRIA/Item_Detail.aspx?WebsiteKey=3f18c87a-d62b-4eca-8ef4-9b09309c1c91&iProductCode=C689F&Category=FREEPUBS&OrderLineId=71a52fd5-34ac-4bd9-b219-e1c97a45e059 Culvert Design and Operation Guide (C689F)]</u>
:*<u>[https://www.fhwa.dot.gov/engineering/hydraulics/pubs/12026/hif12026.pdf Hydraulic Design of Highway Culverts]</u>
▲The table below highlights some of the commonly used check files when reviewing 1D culverts. Although this list may not be all the check file you could use to review 1D culverts it is certainly a good starting point. The full list of TUFLOW check files can be found <u>[[TUFLOW_Check_Files | here]]</u>. <br>
! style="background-color:#005581; font-weight:bold; color:white;"| Filename prefix / suffix
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| [[Check_Files_1d_inverts | _inverts_check.mif<br>_inverts_check_P.shp]]
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| [[Check_Files_1d_IWL | _iwl_check.mif<br>_iwl_check_P.shp]]
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| [[Check_Files_1d_nwk_C | _nwk_C_check.mif<br>_nwk_C_check_L.shp]]
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| [[Check_Files_1d_nwk_N | _nwk_N_check.mif<br>_nwk_N_check_P.shp]]
|}
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Any further questions please email TUFLOW support: [mailto:support@tuflow.com?Subject=TUFLOW%201D%20culverts%20help support@tuflow.com]
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