holga_r

Hi Gianmarco,
Thanks for your answer.
I'm trying to simulate both exchanges between groundwater and soil system and exchanges between the river and the groundwater reservoir, and also exchanges between atmosphere and soil/groundwater, by setting "inflow on top" equal to infiltration and modeling both saturated and unsaturated flow.
Unfortunately we don't have much information about the water table, because we are studying a mountain basin where there are no wells. However, we know that water table may touch the surface in some zones and stay under the surface in other zones. Obviously I would like water to leave the model right where the water table touches the surface, i.e. through superficial nodes that become saturated.
I found it so strange that nobody seems to have used feflow to create a 3d unsaturated-saturated flow model.
Anyway I'm really interested in your publication, you can send it here:
alice.cusi@unimore.it

Thank you again,  bye!
Alice

Hi,
I would like to use FeFlow to model subsurface and groundwater flow across a river basin having a drainage area of about 500 km2. I would like to simulate both groundwater flow in the saturated zone and specially the flow in the unsaturated zone, in order to compute the fluxes from groundwater to the surface and vice versa. Unfortunately, I couldn't find any example or study in literature at a similar scale, where Feflow is used to solve a unsaturated flow problem. Perhaps, could anyone indicate me some paper or example that could be useful to my work?
However, I started trying with a unsaturated steady flow model having the 1st slice coincident with the topographic surface and a total depth of 200 m, all layers parallel to the surface. After consulting geological studies made in that area, I set Ks = 3x10-7 m/s in the first 100 m from the top and Ks = 10-8 m/s in the lower layers, and also tried different vertical discretizations. In order to allow water to exit the model through the surface, I set a 3rd kind boundary condition on all the superficial nodes with hR equal to the elevation, so that, when a node gets saturated (hR is bigger then elevation), an outflow is expected. Inflows are instead coincident with the mean annual recharge (300 mm/yr is the value I'm using). Hence, the inflow transfer rate is equal to zero, while I tried different values for the outflow transfer rate. The problem I have is that water doesn't seem to leave the model, because all the resulting configurations have saturation equal to one in all nodes except one or two nodes in the middle of the basin where saturation is next to zero. I also tried using constraints for boundary conditions but I couldn't get any improvement but convergence got more difficult, instead. Do you think my strategy for boundary conditions is a good one or is there something wrong in my model, due to some aspects of Feflow that I probably ignore?
Afterwards I would also like to perform some transient simulations but first of all I would like to obtain a good steady-state simulation.
Thanks!
Alice