[Luis Partida]

I think a better answer could be discussed if you showed the results with your cells shown and a view of your precipitation input over time. In my opinion your time step is far to high, remember for the default Diffusive Wave a courant condition should be satisfied of less than or equal to 1 with a max of 3, however I recommend 1.

Also you should check your output log for continuity, this would show in your % error if volume is truly disappearing. But in the end I do think this is a matter of a cell size, possibly orientation, and computational time step issue.

[Luis Partida]

Check your internal bridge cross sections.

[Luis Partida]

The unsteady simulation will give you the most accurate results assuming you have low and high tide data. As far as stabilizing that model, there are endless possibilities, check your HTab and time step compared to your cross section spacing.

The steady state model will give you your most conservative answer in that at high tide of X elevation, my worst case scenario for impacts, or whatever your scope, it would be Z.

[Luis Partida]

In my experience I have only utilized the “compute separate WSEL per face along the BC line” to determine if I needed to break up my BC line in to multiple based on face elevation variances. The final output is an averaged WSEL along the cell faces if I am not mistaken. So if I had a full 2D model where I believe there was potential for WSEL variances, I would select the “compute WSEL per face…” and run the model, check some of the cells and either break up the BC line into a couple different locations and turn that option off or was satisfied with a single BC line and turned it off and re ran(simplify calculations)

[Luis Partida]

I have a proficient engineer here in python that investigated the same process. Short answer is NO. It seems that RAS Mapper calculates Q on the fly based on cell orientation to your profile line so it is by default not stored in the regular HDF file. There is a separate HDF file created once the profile line data is calculated but still….. Unfortunately…this is a limitation

[Luis Partida]

HTab parameters are def something that can help (100 may not be enough) but not just this. This could be a product of your min/initial flow, timestep….there are so many parameters to play with to help resolve your solution. But the easiest way, without messing w RAS default options and tolerances is to play with flows and time steps. You could just be drying out your model causing the spike

[Luis Partida]

I never have issues with this but I also never select “merge inputs to single raster”. RAS will automatically create an .hdf of the terrain that will be merged but will keep its individual .tiffs as independent terrains.

Unselect that option and it should work. Also remember the order must be in order of burn to base. Meaning if your base surface is the channel and your other surface is just a burned tributary, the burned tributary must be on top in the order

[Luis Partida]

Just as a question, have you tried changing the culvert type to box or circular? I have never used elliptical in 2D so that’s why I ask the question.

I also would attempt to redraw the XY coordinates and override the culvert data once again. The culvert stationing may be off, though visually it looks fine, you never know

[Luis Partida]

Since its a 1D model you can try cross section point filtering in the tools and set rules based on slope. Hopefully this will help if the trees are high in slope.

[Luis Partida]

short answer, Yes always calculating with that flow regime. But habitually I still turn it on because im a robot

[Luis Partida]

The weir coefficient and equation selected plays a large role here. Try reducing the weir coefficient to the recommended RAS settings based on how it is acting in the system. You may want to also try selecting “2D equation” to be used rather than the weir coefficient as well as play with the later structure flow stability factor and weir flow submergence decay exponent. By default they are set to “1” and can be changed to a max of “3”

[Luis Partida]

Yes^^ I recommend using dummy 2D inline structures if you are looking for the best results. Just do a weir with a height of 0.01-ft above the terrain. Make sure you either use the 2D equation or drop the weir coefficient to 0.2 or lower if you expect complete submergence

[Luis Partida]

Im aware of that 1D method, however you are not dealing with a 1D complete model. You have a 1D2D model that you are looking to remove the 2D area and combine reaches. There is no easy or quick way to do this.

[Luis Partida]

I have gotten this a couple times and its SO annoying and I still don’t know the actual cause. You can try deleting the .hdf geo file and try re running. The only other option I completed was continue deleting bridges until the error no longer exists then re adding them one by one and re running after each

[Luis Partida]

Its your computational interval of 1 hour. Reference your cell size to come up with a more appropriate computation interval and that will increase your run time. This is based on the courant criteria

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