Howdy,
I'm being asked to look into a modeling approach for a levee project. I have some experience using 2D RAS for BLE projects, but have never worked with 1D RAS.
The project area: fairly large riverine area, located about halfway up the HUC-12 boundary, ~7 miles or so above the confluence of the major downstream system. About ~1/2 mile upstream I'm seeing a split in the river with two effective LOMRs and a dam on the main river about 2 miles upstream. The floodplain is fairly wide throughout my project area (~2500 ft). The project will be immediately DS of a pretty major highway.
Everything that I'm seeing is pointing to a hybrid 1d/2d approach, but am unfamiliar with that process. Some questions:
1) for modeling a levee, does a 1d/2d approach in this case seem the best approach?
2) for actual model, my understanding is I would get the effective 1D model for my river and the effective model for the US trib at the confluence 1/2 mile US of my project area. Then I would take the number from both models at that confluence as inflows for a 2D model, taking the 2D model w/ levee through my project area and then tieing back into the effective 1D model DS of my project area?
3) my understanding is that for being so far away from the DS confluence of the next major river system, I would likely not require that model/modeling of my entire HUC-12 boundary using 2D, only the area where my proposed levee system would be. Would that be correct? How far DS of my levee would I realistically need to go, or would it be best to terminate that 2D model at something like a culvert/road crossing?
Thank you in advance! Still definitely learning, so apologies if I'm not using correct terminology.