The uppermost bed layer (thickness = 0.15m) disappear after the first snapshot

** At time 0 day, the initial bed condition seems right: I set up two bed layers, the uppermost is 0.15m, the layer above is 0.35m (top_layer_disappear.png). However, after 0.04166667 day (about 1 hour), the uppermost layer became layer1, and the thickness became 0.453125m from 0.15m at Time 0 (top_layer_disappear-2.png). The value “0.453125m” is not near “Layer1 thickness 0.35m” or near “Layer2 thickness 0.15m”. Could you tell me what does it represent? ** What’s more, in this model, once the model moves from Time=0, the layer in Viewplan can be seen only Layer1, Layer 2~4 is “blank”. I know this phenomenaon may associate with two additional layers, but I cannot understand why layer2 is also missing (top_layer_disappear-3.png), which is defined by me instead of generated automatically?

Hi T X,Sorry for the delayed reply.First, are you using the original EFDC sediment transport model or SEDZLJ sediment transport model?If you use the original sediment transport model, then layer 1 will always be the bottom-most layer (the one farthest from the sediment-water interface).If you used the SEDZLJ then it is the opposite, where layer 1 will always be the layer interacting with the overlying water column.Second, if you have set a max layer thickness in your sediment transport model settings, then EFDC will try to redistribute the bed thickness for any layer over this user-specified threshold. Have you been using the max layer thickness settings?Third, do you have active parent layering turned on for armoring? That will split the top layer into active and parent layers. If you did this, what thickness did you specify?Thank you for your question,Tom

Dear Tom, I am so glad about your answer. Below is my reply of your question:(1) I use the the original EFDC sediment transport model;(2) I tried to change some different values about “max layer thickness”. However I cannot remember which value is used when I posted this question. As I think my konwledge is limited, I decide to build “one-layer” sediment bed now. Please help me about “How to assign different zones of different sediment to a one-layer uniform bed?” if you have time. Its website is: I don’t activate “Bed Armoring”. I use “No Armoring”.

It seems that you have quite a lot of troubles with the Sediment setting. Please download the TraKhuc Coastal Model and use Ctrl+T to load that file to the model you will understand it better, I hope.

That is very useful and informative reply.Urban Sales