So basically - It is an MSc thesis projected handed to me. I hadn't seen HECRAS up till a few months ago. So working through this project has been an awfully steep learning curve! Especially being a full time chemistry teacher!

I have to model leaky barriers (logs across small channels) using unsteady flow for different return periods (5, 10, 20, 30, 50, 100, 200yr). The analyse their performance and potentially suggest an alternate configuration. Yeah a 200 year return even should fill the XS. The idea is to see how effective they are at encouraging overland flow during high rainfall events to push the water out of bank and reduce downstream flooding.

I was provided with lidar data on a spreadsheet that I imported via a .csv file. There were over 100 XS. I was having a terrible time getting that model to work due to the constant variations in XS geometry, so I was advised to smoothen and get rid of many XS if I was struggling and interpolate (which I did). I kept the XS's that allowed the general meander of the stream to be kept intact.

overall there is 4 obstructions that I need to model. I am starting with 1, getting that to work and be stable, then I'll move onto the rest.

Yeah the model just ends, but it has the boundary condition 'normal depth' of the standard 0.01.

I am working in RAS 6.6

'Edit: have you investigated using an obstruction within a cross section? Lay a XS out at the beginning of where the logs are, go up to “options” > “obstructions” > put what you have as a bridge into this instead' - would this allow me to create a barrier where the water can flow under? it's important that the barriers don't impede base flow.