Pumping well leads to a decreased water level in the whole model

Hi Feflow-Forum,

I have calibrated a 3D-model. When I insert a pumping well (4th boundary condition) into that model there is not only a drawdown in the well, but also the waterlevel is decreased in the whole model in comparison to the calibrated model. I also tested this with a very simple model and there is the same problem.
I found out that with higher vertical discretisation the decrease in the whole model gets smaller, but there is still a difference of about 5 cm to the water level of the original model.

Does someone know why there is a decrease in the whole model?

Has somebody an idea how to overcome this problem?

Thank you very much
Maik

Dear Maik,
I assume, that you haven't assigned pumping rates to your well boundary conditions, is that right ?

If you have used multi layer wells, in my experience your boundary nodes work like a vertical connection between all layers, where your well nodes are defined.
A groundwater exchange between all layers is enabled. If you have a layered aquifer with different conductivities, this effect may produce your water level changes.

Best Regards, Henilein

Hi Henilein,

thank you for your answer. I have assigned a pumping rate to the well boundary condition and there is only one aquifer which has vertically homogeneous conductivities. So different conductivities can not be the reason for the water level changes far away from the well. I assigned a pumping rate of 492 m³/d on the well node of the lowest slice of the aquifer, to the well nodes on all the other slices of the aquifer I assigned a pumping rate of zero.

Kind Regards, Maik