basics of qual2k

[Shubhojit Dey]

hi all,

i have asked this question before too but now i am under the pressure of a deadline for my thesis work and i need to know a few things. i will list out the things which i need help on.

1. i have to do a simulation of BOD and DO for a river. what data do i compulsorily need in order to do the simulation correctly?

2. what data are not required for simulation of the above? ( i mean which data i can ignore or leave blank while filling out the input in qual2k)

3. how to do the auto calibration? ( i seem to have no idea about this!)

please help!

[Adam Rus Nugroho]

Hi Shubhojit Dey,

1. QUAL2k is a framework for creating a one-dimensional stream water quality model. It creates a model based on the headwater quality data and many river parameters included by the developer.
- First, you need to determine your river segment. It is done by filling the data of the river segment in the Reach worksheet. The first reach in the segment should be the headwater (upstream).
- Second, you need to fill the Headwater worksheet using the river water quality data.
- Third, if there are pollution sources available, you should input the water quality of the sources in the Point Sources and Diffuse Sources worksheets. A point source is a source in which you can determine the distance from the end of the stream (example: in Km 5), while a diffuse source is a source in which you determine the range of distance (example: from Km 10 to Km. 5) from the end of the stream. 

- Fourth, you need to determine the coefficients for the river hydraulics and water quality. The coefficients for hydraulics are in the Reach worksheet (such as Manning) and the coefficients for water quality are in the Rates worksheet. You can choose to input the water quality coefficients in the Reach Rates worksheet instead for the more detailed input. You can also specify the atmospheric parameters in several worksheets from Air Temperature to Shade. 

At least those four steps are needed to run and create a model. Afterward, there is a calibration step utilizing the yellow worksheets and includes the trial-and-error process in specifying the coefficients.

2. I have shown the worksheet which at least you need to fill in number 1. But, I will add something here. Please take attention to the color of the cells. There is meaning to them. You should make an input only in light-blue cells (for models) and light-yellow cells (for calibration). Green cells are the resulted values from the program running, and pink cells are the model results.

3. I don't really know about the Auto-Calibration. I will leave that answer to the experts. But, I can tell you how to do the calibration.
The WQ Data worksheet and other yellow worksheets are used for calibrating the model. If you input data in the WQ data worksheet, the black square dot will appear in the model (graph). The dots show the observational data which the model should follow in order to be properly calibrated. To adjust the model for following the dots, you should make some (usually a lot) of trial-and-error in specifying the model coefficients and parameters, especially in Rates / Reach Rates worksheets. 

[Shubhojit Dey]

thanks a lot for your response adam. you really did put an effort in explaining things from very basics. i will take a note of the same and try to work on your suggestions.

could you provide me a sample q2k file? i know there is one in the software package but i need some more for more references. 

thank you!

have a great day

[Adam Rus Nugroho]

I would give you a sample file, but currently, I do not have any except the included file of the software package and another from a person from this group who contacted me for personal advice on his q2k error run, maybe a year ago. However, I think I can not give you the file from this other person without getting permission first from him.

[Shubhojit Dey]

its alright adam. you have helped me a lot. still if you find something for me, here is my email : dey...@gmail.com

thanks a lot!

[rahat zehra]

Respected Sir,

I am getting the error message; _ Run time Error 11. Division by zero.Could you please guide me on this