Parameter adjustment problem of TP

Dear Professor,
I want to simulate TP,but if I only have the data of TP, and do not have the data of RPOrg P, LPOrg P, DOrg P and TPO4-P. Does it matters?
When I am adjusting the parameter, I found that when I change the value in the window: Water Quality – Nutrients – Phosphorus, the results were exactly the same. For example, I have tried to change the value of “Partition Coefficient for Sorbed/Dissolved PO4 (to TSS or TAM)”,“Minimum Hydrolysis Rate of RPOP (1/day)”,“Minimum Hydrolysis Rate of LPOP (1/day)”,“Minimum Mineralization Rate of DOP (1/day)”,“Constant1,2,3 used in Determining Algae C:P Ratio (gC/gP”. the results were exactly the same.
(1) Is it normal or there is something wrong with my model?
(2)What parameter matters significantly with the result of TP?
(3)So far, my simulated result was higher than the actual measured value, how to adjust the parameters?
(4)When I am adjust the result of TP, should I only adjust the parameters in the tab of “Water Quality – Nutrients – Phosphorus”? or I should adjust the parameters in other tabs also?
I am looking forward to your answer, thank you very much!


Hi Ravina, The scale of question you have put up is very complex. Water quality is more complex and requires more knowledge of the internal processes and parameters. In order to simulate total phosphorus you need to have all the data input into the system. If you are not simulating algae, then the mass loading in the system is zero, then all the parameters multiplied by 0 would be zero. There are so many coefficients in the kinetics of the water quality module which needs to be properly set up. So, without the real data and your model we cannot tell exactly what went wrong and why you didn’t get the expected result. Here is a brief summary of how the water quality parameters in EFDC are calculated. If you are interested to know more details on how to properly set up the water quality model you can attend one of the training sessions from Dynamic Solutions International LLC (EFDC Explorer). The training will have experts who have performed modeling studies on water quality on numerous projects. You can also look at the water quality manual and some examples from the download section. Good luck. Best, Janesh Devkota