Setting of "light extinction due to TSS" in water quality model

I discovered an issue with version 12.1. When I set up the water quality model, the value for “light extinction due to TSS” is automatically set to 23 (1/m), which is unreasonable. When I change it to my desired value, such as 0.1, the output values do not change. Moreover, after saving and closing the model, the value resets to 23 the next time I open it. Is this a bug?

Hi, can anyone confirm if that is a bug or not?

Hi qingyan,

I tried to reproduce your issue by activating Temperature, Water Quality and Sediment Transport modules on an available Hydrodynamic model that I have then adjusting the coefficient. I did not experience the same problem. Please see my Solar Radiation settings in the attached screenshot. After the model is saved and reloaded, the entered value for TSS Light Extinction Factor is preserved.

Please let me know if we are on the same page.

Hi, Linhntk03:
I’m not sure if the route you provided works. My route is: Modules → Water Quality → Kinetics → Light Extinction → Light Extinction due to TSS. I’ve included a screenshot below. Unfortunately, I still cannot fix this problem. I can save it with0.1, but when I reload it, it reverts to 23. I’m not sure why this is happening. Where is the page in your screenshot? I couldn’t find this route.

Hi, Linhntk03:
can you find my problem, is the settings the same in your side?
Qingyang Huang

Hi Qingyang,

Sorry I failed to keep myself updated with your message.

My route was Modules → Temperature → RMC then Settings → Solar Radiation. To my knowledge, the one I adjusted and the one you adjusted were the same and if one of them is updated, the other will be changed (upon the saving of the model).

On the other note, strangely I still cannot reproduce your issue following the route you provided. Nevertheless, one thing I’m sure is that this is not the case in our latest updated version. So, please be assured that the light extinction coefficient for TSS is and will be modifiable as expected in the coming release. You are welcome to request a EE12.1 patch version by sending us an email via

Thank you very much for your feedback!