Subject: Zero water balance when i need deficit Posted: 1/28/2025 Viewed: 445 times
Hi guys, i'm doing my thesis around the Delta of a river. I'm trying to calibrate my model but I stambled upon an issue I don't know how to fix.
My water balance (which I calculate from the Groundwater Inflows and Outflows) has very long periods being equal to zero and that is not normal. What parameters should I change or check ? The perfect outcome would be for me to have a deficit in my water balance, but definately not zero.
Mr. Doug Chalmers
Subject: Re: Zero water balance when i need deficit Posted: 1/28/2025 Viewed: 435 times
Hello Μαρία,
What does your groundwater system look like? Do you have river objects or catchments that connect to the groundwater?
For your river to groundwater object connections, you should see Groundwater Inflow/Outflow results for both your river and groundwater objects. To adjust this connection, you should adjust the groundwater object hydraulic conductivity, specific yield, horizontal distance, wetted depth, storage at river level, and maximum head distance. Set the method in your groundwater object to "Model GW-SW flows". Then, in your river reach, set the groundwater inflow volume and groundwater outflow volume to connect to your groundwater object under where it says "from Groundwater". Finally, set the reach length in your river reach. For more info, see the WEAP Help for Groundwater-Surface Water Interactions.
For your catchments, make sure you have a runoff/infiltration links from your catchments to any groundwater nodes that would receive groundwater inflow. If you are using the soil moisture method, then the preferred flow direction would be a key input. See the results for Z1 (moisture in the upper bucket) and Z2 (moisture in the lower bucket)- having no moisture may prevent infiltration into your groundwater. If you are using the simplified coefficient method, then adjust the runoff fraction of the runoff/infiltration links to determine the proportion of outflow going to groundwater versus surface water.