River as a boundary - Having troubles with the transfer rate

Hi feflowers,

I'm an Masters student and my research uses the Feflow as the main software.

I have on my model a river as a boundary so I'm using the 3 rd type boundary condition (cauchy type - fluid transfer BC) but I don't know how to define the transfer rate. It's on the in/out flow rate? If yes, how can I define the magnitude of the in/out flow rate?

I only know the conductance value on Modflow but I'm having troubles on Feflow.

Thanks a lot !!!

Yes, the in-/out-transfer rate is the parameter you may in combination with transfer boundary conditions (Cauchy type). The inflow/outflow at transfer boundary conditions is calculated from the relevant area, the transfer rate, and the difference between reference and groundwater head:

    Q = A*?*(href-h)

where
          Q: inflow or outflow to/from the model
          A: relevant area
          ? : transfer rate
          href: reference water level
          h: current hydraulic head in groundwater

The transfer rate is a conductance term describing the properties of a clogging layer. It is defined as

    ? = K/d

          K: hydraulic conductivity of the clogging layer
          d: thickness of the clogging layer

Sorry, ? represents the greek character Phi

Björn Kaiser thank you.

I read something similar to this in the feflow user manual. Do you know the magnitude of the in/out transfer rate for rivers? I know this rate depends on the geological factors and others but I wanted to see an example.

Thanks !!

The transfer rate may range over several orders of magnitude (e.g. 1-10000 10-4 /d). Usually, this parameter is subject to calibration.

Thanks.

Analysing my "problem" I found a value that's compatible with my river bed. Now I'll try to simulate.