Water age changes


I’m running a model of river and I noticed that by increasing the number of layers, velocity decreases and depth increases. Although these changes are not big (in some case up to 20 cm difference in depth), when you calculate other parameters such as water age, it makes a big difference (in my model up to 6 hours).

I believe that this is not related to my model, because I ran one of the models from the DSI website (Ohio River Storm Impacts Example) for different number of layers and got the same problem.

Any ideas on what would be the possible reason?


Thanks Tinh for your response.

I have attached a plot that shows the water depth at cell (62,5) of Ohio river storm impacts example. I ran it for 3 scenarios with 1, 4, and 10 layers. As it shows, water depth increases as number layers increases.


Thanks Tinh. I sent it to your email.
I’m using EE7.1

Thank you for posting this question. It has caused us to go back and look at this question in more detail. The fact that there is a difference in WS elevation with changing KC is as we expected due to changes in the shears applied in the water column for the multilayer vs depth averaged cases. However, we did find that the way EFDC handled a single layer was not consistent with theory. We have made an adjustment to the code that will be available in subsequent releases.

In the attached image we see the improvement attained and that over 50 km there is difference 25 cm between 1 and 8 layers, to us this seems reasonable. The difference between 1 and 4 layers is now only a few centimeters. Attached files profile_wsel_new-old.emf (45.6 KB)