PLAPS parameter range

[rahulja...@gmail.com]

Hello,

I have finished the SWAT CUP calibration using the SUFI-2 algorithm. In that I used 14 parameters. All parameters values are fine. But I'm confused regrading PLAPS, TLAPS, and SLSSUBSN values.

In the Sensitivity analysis the SLSSUBSN value shows nan for t-stat and p-value. The provided the range of r_slssubsn.........-0.2 to 0.2.

For PLAPS the best fitted value is 985mm/km.

For TLAPS it is -4.85C/km.

Are these values correct or should I use a different approach. I have tried the separate calibration of PLAPS and TLAPS still got the similar value around the one I got using the all parameter at once approach.

Thank you in advance.

[omc...@gmail.com]

Hi,

PLAPS and TLAPS only affect your model if you had set elevation bands for snow modelling when creating your SWAT model in the GIS interface, If you didn't, then don't worry.

If you did set elevation bands, TLAPS and PLAPS matter. To see if those values make sense, you have to see you observed annual temperature and precipitation, and see how they vary over the elevation, if the slope of this analysis match your best fit for both, then is OK. If not, you are misrepresenting your snow behavior and should try another approach.

Kind regards,

Oscar

[rahul sharma]

Thank you for replying.

My watershed is In a tropical environment specifically the western ghats. The elevation ranges from 26-2600m. So I have added five elevation bands for watersheds with elevation range greater than 1000m. 

The lowest rainfall station is at 350m and highest is at 950m. The average annual rainfall is 2100mm and 2600mm, respectively.

Rahul Sharma

Research Scholar (Ph.D.)

Center For Study of Regional Development

School of Social Sciences

Jawaharlal Nehru University

New Mehrauli Road, JNU Ring Rd, Delhi 110067

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[omc...@gmail.com]

Hi,

If you are modelling a tropical watershed, then I do not believe that snow is an important component.

As a comment, How precipitation and temperature changes with elevation it is obtained from your stations, then put in SWAT as a value, and in SWATCUP you make it vary from -10% to +10%, or using the ranges that you got from analyzing multiple years. If you are calibrating just seeing which one give you the best result or fit, then you are just searching for the best numerical solution, not for the best actual representation of your study area.

In example, if I am analyzing a mountainous watershed, in which temperature decreases with elevation, and usually precipitation increases. but my best fit is the contrary, then I just found a numerical solution, but not a good representation of my watershed actual behavior.

Regards,

Oscar

[rahul sharma]

Okay. Now that I have provide you the range, please suggest me the parameter range that I should use.

The SWAT cup provides a default range of:

PLAPS- -1000 to 1000mm/km

TLAPS- -10- 10C/km

Please suggest.

Rahul Sharma

Research Scholar (Ph.D.)

Center For Study of Regional Development

School of Social Sciences

Jawaharlal Nehru University

New Mehrauli Road, JNU Ring Rd, Delhi 110067

To view this discussion visit https://groups.google.com/d/msgid/swat-cup/1389eed1-b833-465f-8eb1-99988c64eb90n%40googlegroups.com.

[omc...@gmail.com]

the range is obtained based on your observed data. I cannot give you any suggestion from a place where I have no previous information!