Dear WEAP users,
I am currently using the Soil Moisture Method (SMM) to represent my overall catchment. The catchment is not connected to the groundwater (GW), and I have manually entered natural recharge values directly into the GW node (using the Specify GW–SW Flows method).
However, when I create an infiltration link from my SMM catchment to the GW, the inflows from the catchment become very small compared to the known natural recharge. Therefore, I would like to ask: Should I still keep using the measured natural recharge values in the GW node, or should I instead calibrate the deep soil layer parameters of the catchment and remove the predefined recharge values?
Additionally, I am curious about the hydrological interactions when no infiltration link is created between the catchment and GW. As far as I understand, the deep soil layer simulates interflow and baseflow processes directly to the river. However, in such a setup, although I have groundwater and demand sites supplied from GW, it is not possible to represent baseflow as an outflow from the GW system (not accounted for in the GW storage balance). Could anyone provide further explanation or suggestions about the best way to represent this interaction?
Thank you in advance,
Selin

Selin,

A few thoughts. As you know, there are alternative ways to calculate the recharge- either through Model GW-SW flows where it's connected to the groundwater outflow of the catchment, or through Specify GW-SW flows where you can directly estimate it. I'd ask yourself, does your catchment account for most of the recharge area of the groundwater? If so, you'd expect that the infiltration to the groundwater should be close to what you're expecting in total recharge. So, just make sure you're confident in your calibration. But, you can use either/both method to simulate your recharge.

In terms of your last question, have you already considered the SW/GW interactions modeled between river and groundwater node? That gives the seepage and baseflow interactions between surface and groundwater that you might be looking for.

Cheers and good luck!
-Doug