Issue with Fluid-transfer BC (model got distorded...)

I'm working on a model of an alpine aquifer with a river partially connected. To model the relation between the river and the aquifer, I'm using the Cauchy BC. I followed the instruction of this post [https://dhigroup-support.microsoftcrmportals.com/knowledgebase/article/KA-01252/en-u], however I'm probably doing many things wrong as the result looks very weird Below is how I did the model: - select the nodes of the first and second slices of the mode (the first layer is about 10-20m thick) - assign a fluid transfer BC equal to the elevation (this what I guessed is the reference head) - assigned an In/Out transfer rate of 0.0001. After running the simulation, the elevation got distorted. Attached are printscreens of the model before and after the simulation. Any idea how to solve this?

Hi Lucien, If you are solving the groundwater flow equation with the option "Free" surface, then FEFLOW assumes that the elevation of Slice 1 coincides with the phreatic surface (Pressure = 0 kPa). Therefore, the model elevation will change accordingly during the simulation. You can solve the groundwater flow equation by using the "Phreatic" option or the Problem Class Richards. We have dedicated free training course about all these options. You can register with the link below: https://www.theacademybydhi.com/course-sessions/feflow---behind-the-flow-11600061-142 Best regards Carlos Rivera  

Thanks Carlos, I'll check the training. Best, Lucien