Groundwater Routing

[nwsmith]

Hi, I'm currently looking at transferring a previously built watershed model into Raven. This model routes surface water to downstream sub-basins but also provides a transfer of groundwater to the downstream sub-basin groundwater. Is it possible to pass both surface and groundwater downstream in this manner, or is downstream sub-basin water transfer only through "SURFACE_WATER"?

Thanks,
Nathan

[jrcraig]

Hi Nathan,

While we are working on the development of an integrated groundwater model in Raven, it is not yet ready for prime time. As of now, all interbasin water transfer must be via surface water routing.

That being said, if essential, there are probably some workarounds- if you provide some detail of how this was done with the previous model, I may be able to provide some insight into how this could be handled indirectly.

Regards,
James Craig

[nwsmith]

The model I'm trying to emulate just provides a groundwater transfer to the downstream catchment groundwater based on a constant rate (with different rates for different catchments). It's a conceptual model so quite simple but does include transferring groundwater downstream without it going to surface water. Basically, it calculates an amount of water discharging out of the catchment groundwater store which dependent on the amount in storage using a linear reservoir model. Of that water, a portion is sent to the downstream catchment groundwater storage based on a constant rate (the rate is somewhat calculated based on Darcy's Law) while the remainder goes to the downstream catchment surface water (if the linear reservoir outflow calculation exceeds the constant rate groundwater transfer rate).

I've modelled this in the following roundabout method so far:
-A baseflow linear model calculates the amount of water discharging from the groundwater basin (conceptual store "GW_STORE")
-Since this algorithm sends the water to Surface Water, I then flush surface water to a temporary store ("GW_OUT1)
-From that temporary store, I use PERC_CONSTANT to calculate and send a portion of this water (GW_OUT1) to another temporary store (GWOUT2), this is the portion that needs to go to the downstream catchment groundwater
-The remainder in GW_OUT1 gets flushed to the catchment surface water as it represents the amount above the rate to be transferred from the catchment groundwater to the downstream catchment groundwater

Thanks,
Nathan