I have a large model with a large river network. The top of my model is defined by the DTM. I have a shapefile of the river network that I want to import as a Fluid-transfer into my model. How I do this in a way that the BCs will be assigned to the valleys of the DTM?<br> I&#160;tried the method I use for the hydraulic properties, selecting the whole slice and it applied the BCs to all the nodes of the slice which is not what I want.<br> <br> I also want to apply constraints to those BCs, once FEFLOW floods large areas of the model, which is not correct. However, and once the river network is big, is defined by a large number of nodes with this BC type. So it is too time-consuming define the constraints node-by-node. How can I define constraints for the whole river network in a fast way?<br> <br> And just to be sure, the values of the Fluid-transfer BCs are the water height of the river, right? So if my river has 1 m of water, that is the value I should define in the BCs, correct?<br> <br> By the way, so far I am simulating this river network as head-constant BCs and when I check the imbalances by adding the BCs values and recharge (entered through In/outflow on top/bottom) in an Excel sheet and compare with the values shown in FEFLOW Rate Budget panel I get this: I f the 1st slices is defined as Phreatic, then the Imbalance in Excel match that of the Rate Budget panel. However if I define the 1st&#160; slice as Free, the Imbalance in Excel and in the Rate Budget panel do not match and have a mismatch from 2 to 3 orders magnitude. Why is this so?