[drainage321]

You nailed it! That is exactly my concern with the sections – I’ll just have to monitor and tweak until it represents the correct flow pattern. You helped me confirm what I thought I was going to have to do – I guess I was hoping for an easier way out

As long as I have your ear: Next topic – The average length of obstruction in determining the expansion reach length: The two bridge approaches average 500 ft of obstruction in relation to the floodplain map. If I calculate the expansion length, I come up with a downstream expansion length of 1,126′. Does that truly mean my downstream x-section should be located that far away – that is almost to the next bridge?

[drainage321]

Some answers:
1) Modeling existing conditions to size a new bridge
2) Steady state – developed flows utilizing the regression equation as there are no applicable rain gauging stations on the reach
3) I’ll be modeling flow up to the 500 year event. The creek/channel itself will contain up to the 2-year (normal flow) event. everything above that is conveyed within the overbanks. I’ve attached a floodplain map. Just based on seeing the sight – I would say the floodplain on the right of the channel is wider than what is shown on the map. Section 13 to 18 to 19 for reference.

– The 500 will most likely overtop the parallel roadways so I will keep the sections extending beyond – thanks for pointing me in the right direction on that item.
– It’s RAS that crashes. I think I found that if I try to add multiple blocks within the graphical x-section editor it crashes. If I manually enter the blocks within the normal x-section editor – it doesn’t. A lot more time consuming but I guess I have no choice.

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