Subject: WEAP moel calibration using Simplified coefficient method Posted: 5/9/2016 Viewed: 2254 times
I am calibrating a WEAP model of a basin and I am using the simplified coefficient method because I do not have any data required for the soil moisture method. I have the following questions.
1. In cases where the ETref is more than the precipitation, the surface runoff becomes zero ? how do i compensate for this. Should I add a ground water component which can compensate for the reduced availability of water? In the Soil Moisture method (SMM), I believe that there is an increase or decrease in moisture which helps in maintaining a flow on the surface. How do I capture this in the simplified method ?
2. So if I have a catchment with no agriculture, no demands for water and just have a land area where there is precipitation and ETref, how will I calibrate it using the Simplified method. Is it more like a trial and error process to match the stream flow gauge or is there another way/knack to do it.
My understanding of hydrology and water management principles is still in its nascent stages, kindly correct me if I am wrong.
Subject: Re: WEAP moel calibration using Simplified coefficient method Posted: 5/11/2016 Viewed: 2218 times
To answer your first question, the Simplified Coefficient method is indeed simple. When the ETref is more than precipitation, there will be no surface runoff. You could add a groundwater component and link it to the river, but you would also have to account for annual recharge in the groundwater. The Simplified Coefficient method cannot capture the detail of stored water like the Soil Moisture method.
We calibrate the catchments using the historic streamflow records. There is an element of trial and error, but you can structure it in WEAP to make it easier on yourself. I like to build scenarios and then test the different parameter quantifications in the different scenarios so I can compare them in the results section. This way I can see the impacts of changing different parameters, which helps me understand how I can produce the streamflow closest the existing records. You can also use PEST calibration in WEAP to help you - I would also use a scenario for that.
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