agreed that is what is messing up my WSE, unfortunately I can't change the size because it is a DOT culvert and they installed it without doing any analysis or anything.
Thanks,
I was thinking about it this weekend. the condition is a backwater/tailwater condition and there is a small amount of slope on the ditch so the water surface profile will be flat and the velocity slow. So, increasing the size of the ditch area will not have an effect. Basically, the...
Initially, the flow was extremely wide IE 500' wide. I believe the issue is that the slope for the channelized ditch is very shallow and it is a backwater condition. We can't upsize the culverts going under the road so we have a tailwater condition, plus the land to get from one point to the...
In general when you widen a ditch shouldn't the WSE go down in your model? I went from a 75' flat bottom ditch to a 150 flat bottom ditch with 3:1 side slopes and it only dropped the WSE about .09. That seems very small for doubling the size of the ditch. Any input on how I could trouble...
I need to preliminary size a ditch to contain the floodplain and floodway. I used Chezy Mannings to calculate, and it calculated a Q well over what my hydrology calculated. I then placed in the Hec Ras model and it over tops the ditch, roadway, etc. I know that the downstream structure will...
So
for example you have a CBC and assume flowing full
IE 5-8x4 CBC assuming flowing full
A=8*4=32 sf
∑A= 32+32+32+32+32= 160 sf
P = 4+4+8+8=24 feet
r=5*32/5*24=1.33
assuming n=.011, S=.0025
Q = (1.49/.011)(160)(1.33)^.67*(.0025)^.5= 1311.79 cfs
For a preliminary sizing I have looked at using the Chezy Manning's Equation for box culverts.
1. can you use Chezy Manning's on CBC that are multiple barrels? If yes do you sum up all the areas of each individual box culvert? Do you sum up the hydraulic radius of each individual barrel for...
All,
How do you model a lake in HEC RAS that is just upstream from a FIS, has a low flow channel, and overtops and floods an adjacent road during the 100 year event. I have a model set up but don't think that I am modeling the lake right. I believe I need to go the path of setting up a weir...
