Subject: calibration and validation Posted: 10/7/2019 Viewed: 8757 times
Hello,
I'm a master student in Jimma University Ethiopia. I am using soil moisture method to allocated water resource in basin, I have problem with model calibration.. I don't know how can I calibrate WEAP? and whichone of parameter should be calibrate?
In a paper I saw the result of calibrate was observed and simulation stream flow in stations. I should select a river and the station of it in PEST calibration,I know, but what is the lower bound and upper bound? and after calibrating wich one of output must be cheek? and I don't know wichone of parameter shows the simulation and wich one is observed?
Is it possible to help me? Please!
Kind regards
Mr. Miroslav Kandera
Subject: Re: calibration and validation Posted: 10/31/2019 Viewed: 8644 times
Hello,
PEST calibration use iteration to modify value of variable that you choose to match modeled streamflow with measured streamflow from gauging station.
It can modify only one value, so in order to calibrate time series of for example twelve months, you need to create new custom variables.
Lower bound is lowest value PEST can use as modified value of variable, and upper is highest one.
I will show my way of approach, in which i calibrate precipitation in monthly time step using custom variables.
I have precipitation data in .txt folders in monthly time step.
Link in expression table is for example like this: .....ReadFromFile(C:\Users\Miroslav\Desktop\zpracovanie zrazok\import dat\READ FROM FILE\C 201.txt) *Key\x .....
What is important is the .... *Key\x .... part.
It is a reference to, by myself created variable.
This variable have created expression that is : ....Choose(Month,a,b,c,d,e,f,g,h,i,j,k,l)....what is WEAP function that chose for current time step (if it is month) which month it is.
a,b,c....l are also variables in x variable branch, one for each month.
Choose function can be used probably for any time step, but i can hardly imagine doing this in daily time step.
If you want to do this in multiple years with monthly time step, you need one more variable "z" and x variables for each year like x2010, x2011 and so on.
expression of "z" variable would then be ....If(Year=2010,x2010,If(Year=2011,x2011,If(Year=2012,x2012,If(Year=2013,x2013,If(Year=2014,x2014,x2015)))))....
what is classic excel-like function that works in weap also.
Hope you or at least someone would get something from this description, i would appreciate any suggestions.
Have a nice day.
Mr. Jack Sieber
Subject: Re: calibration and validation Posted: 11/1/2019 Viewed: 8566 times
Actually, the WEAP-PEST link is able to calibrate several different variables at once, such as Soil Water Capacity or Runoff Resistance Factor (for catchment hydrology). Each variable will be calibrated to a single value. Therefore, you cannot calibrate a time series of values, but I do not think you want to calibrate climate data (e.g., precipitation). Instead, you should be calibrating the parameters of the hydrology model.
Jack
Mr. Miroslav Kandera
Subject: Re: calibration and validation Posted: 11/19/2019 Viewed: 8508 times
Thats true, in my case, i took this approach because i didnt wanted to simulate groundwater, yet i wanted to evaluate relation between precip., outflow, groundwater and ET.
