Some problem about toxics

Hi sir, I would like to simulate a sudden water pollution accident. I am studying a river channel between two hubs, the discharge flow was given to the junction 1 of upstream and the water level at the dam was to given junction 2 of downstream, both of which are given time series documents . However, I found that when I set up the contaminant boundary at upstream, the simulated contaminant concentration does not change over time, that is to say, the entire river is the same concentration. Another question is, if I give a point source pollutant or a region, in the simulation process, the highest concentration of pollutants in the initial release position, it is meaning that the Pollution sources do not migrate with the water, so I wonder why not move downstream with the water? I urgently need to solve these two problems. Looking forward to your early reply.

As I understand you are using flow (discharge) boundary on the upstream and water surface elevation boundary on the downstream. Are you using toxics or dye to simulate the contaminant concentration ? What type of boundary did you use ? Is it time varying or constant? When you said the simulated contaminant concentration doesn’t change, where did you extract the concentration ? Can you show some plots of your upstream boundary condition and your simulated contaminant concentrations ? It is hard to tell how you have set up your model with what boundaries. So, please give us more details with more explanations and or graphs. First thing I would check if your downstream boundary condition. Is your water surface elevation boundary representative of the area or not? I feel that your downstream boundary is obstructing the flow from upstream to leave the system. Please upload your model if you can so it is easier to see what’s going on with your model. Best, Janesh Devkota

Sir, I uploaded my model and upload Annex 2, Annex 2 is the pre-effect I want to achieve. please check, thank you!

sorry, the model upload errors, this is new.

model upload

Hi Wanguo Wu, I looked at your model and found that you have incorrectly set up your toxics time boundary condition series. Toxics Boundary conditionI think you intended to release the toxics up to 151.1250 and then 0 after that. What you need to do is add one more row with 0 concentration. Right now EFDC doesn’t consider 0 concentration beyond 151.125. It does linear interpolation between periods 151.125 and 730 and then use the concentration between 10000 and 0. So modify your data series as follows: Updated seriesThis will ensure that concentration would be zero past 151.13 and no more continuous release of toxics. I ran your model with only dye module and it is behaving as expected.Hope it helps.