Subject: Ground water node characteristics in Soil Moisture method Posted: 1/25/2017 Viewed: 8670 times
I am a bit confused on the groundwater interactions in soil Moisture method.
For a catchment modeled in soil moisture method having a groundwater node connected it to , I am not able to control the amount of water draining into the GW node ( I am not able to set a run off fraction).
1. Is this becasue of the fact that in the soil Moisture method, the second bucket is actually an indirect representation of GW ?
2. If the answer to the above question is yes, then is it right to have a GW node in a catchment modeled in SMM ?
The above questions arise because I want to restrict the amount of Ground water used for satisfying domestic and irrigation demands. But if I use a GW node and connect it to the catchment modeled in SMM, I am not able to control the amount of water going to GW (as there is no control over the fraction in SMM, but is possible in the simplified method).
So in this case if I do not have a GW node but have the catchment modeled in SMM, How can i establish constraints on the GW usage to satisfy demands ?
Would be great to get some ideas on this. I am not an Hydrologist. So probably I am getting something fundamentally wrong!
Ms. Stephanie Galaitsi
Subject: Re: Ground water node characteristics in Soil Moisture method Posted: 1/25/2017 Viewed: 8663 times
First, if you haven't completed the hydrology section of the WEAP tutorial, that's a great place to start, although I don't think it answers your specific questions. But that's okay, I'll answer them.
1) When you connect a groundwater node to the catchment in the soil moisture model, it becomes the second bucket of the catchment. In that sense, you can [sort of] control how much water is going to it by adjusting the preferred flow direction variable in the catchment. This variable controls the water leaving the first bucket - how much of it goes to the second bucket (groundwater in this case) and how much runs off into the river.
Why do you want to restrict the amount of groundwater going to domestic and irrigation needs? Is it because in your system there isn't enough groundwater? If that is the case, I would adjust the preferred flow direction, as well as the deep water capacity and deep water conductivity, which you can use to slow down the transmission of the water, although that is less influential than changing the preferred flow direction.
If you want to restrict the amount of groundwater going to domestic and irrigation needs for other reasons (such as law about withdrawal), it makes more sense to limit the flow in the transmission pipes. For instructions to do this, see the "Refining the Supply" activity (the last section about groundwater) in the WEAP tutorial.
Mr. Vignesh Sridharan
Subject: Re: Ground water node characteristics in Soil Moisture method Posted: 2/25/2017 Viewed: 8391 times
Thanks for your reply. It was very helpful in understanding the SW-GW interaction when the soil moisture method is used.
Topic "Ground water node characteristics in Soil Moisture method"