since English is not my first language, ill give my best to explain my problem and hopefully you can help me.
I have flow in channel which continues on pipe (pipe is over 1200 ft long). When flow in channel is higher then pipe capacity I want water to flow in pipe and over terrain if flow is so high. I use 1D2D model. Lateral structure is set upstream of entrance of pipe and 2D mesh is all over terrain (and pipe).
If I got it right, for designing long pipes I should use lid. I have set elevation of lid on elevation of terrain (road). Is that ok? Station of lids are set close to bank station of XS. Or should lid "cover" whole XS? I did not use Preissmann slot. Should I use it?
Any feedback and comment is more then welcome. Thanks in advance :)
Picture below show how lid is set, and how geometry looks like.
The way I do this in a 1D/2D model is to have to 2D areas (left and right of channel) Along the channel they are connected to channel with laterals. Over the culvert the 2 2D areas are connected with storage area connector. The culvert (or lidded XS) high chord is set artificially high so no flow can go over the culvert deck and is forced into the 2D flow area. If you don't set the deck high it will allow flow to calculated overland, over, and through the culvert. Setting it high keeps flow confined to 2d mesh and culvert.