Changes in culvert shape

[Anonymous]

Hi!
My river is a little lateral tributary of the main river. At the end (section 1) my river falls into the main one (not modeled) and I want to set the critical depth as downstream condition.
For the last 40 meters of my river I have to model an existing culvert with many different concrete shapes:

sect. down.length width height shape
10 0.66m 1.10m 1.25m rectangular
9.5 0.50m 1.00m 0.80m rectangular
9 3.00m 1.60m 0.80m rectangular
8 0.50m 1.60m 0.80m rectangular
7 3.35m 1.00m 1.15m rectangular
6 0.10m 1.00m 1.15m rectangular
5 2.45m 1.70m 1.15m rectangular
4 0.72m 1.70m 1.75m rectangular
3 3.00m 1.70m 1.77m rectangular
2.1 0.10m 1.70m 1.85m rectangular
2 27.90m 1.20m 1.20m circle
1 0.10m 1.20m 1.20m circle
0.1 – main river

Moreover, at section 3 I have a flow change location (from 3 to 5 mc/s).

In Hecras 4.1.0 I can’t change my culvert shape and I can’t model different culverts connected eachother setting 0 in the distance from upstream cross section (in the Deck/Roadway editor).
How can I do?
And which is the best way to model the downstream condition?
Thank you very much!

Alessandra

[Anonymous]

The way to model a culvert that changes sizes, is to model it as a cross section with a lid. You can enter loss coefficients to account for the losses as you move from culvert shape to the next and to account for the entrance and exit losses to the culvert. Use the culvert editor to get an idea of the entrance and exit losses for the lidded channel.

You will need a cross section at the upstream and downstream end of each change in culvert shape or size. You may need to add interpolated sections for a stable model.

John

[Anonymous]

Thank you very much, John!

[Author]

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