In EFDC it is possible to initialize a uniform sediment bed under the ‘Sediments’ tab, under ‘Initial Conditions’, ‘Spatially Variable Bed (Uniform by Layer)’. There is a button ‘Sediment Bed: Solids’ which button brings up the ‘EFDC Bed Constructor’ window where one can define the bed layer thickness and mass fractions of each sediment class.
I am not sure where the information for the cohesive and non-cohesive classes is obtained from for the ‘EFDC Bed Constructor’. In my model I have defined 3 non-cohesive sediment classes (under ‘NonCoh Susp’ ‘Erosion and Deposition Parameters’) with median diameters of 100, 200, and 300 micrometers. However when setting the bed with the ‘EFDC Bed Constructor’ it overwrites my non-cohesive classes (under ‘NonCoh Susp’) to 500, 750, and 1000 micrometers. If I try to set my 3 non-cohesive sediment sizes to 1000, 2000, and 3000 micrometers, then the EFDC Bed Constructor again overwrites these median sediment values to 500, 750, and 1000 micrometers. I am wondering if this is normal, or if I should be able to define the median sediment sizes for each class when creating a uniform sediment bed.
Thanks,
Shalini
We have made a number of changes to the sediment bed generator that are now available in EE7 and upcoming EE7.1. This fixes several bugs and simplifies the process. Please try this and come back to us if you have further questions.
After using the new sediment bed generator I have the following questions and comments:
- When changing the bed thickness under ‘View Plan’ it initially seems to take it, but when saving the project multiple times, and then reopening, it somehow goes back to the previous values of bed thickness.
- After setting the bed with the new ‘Inorganic Sediment Bed Constructor: Uniform Layer’ it seems to work fine, although the Bed and Deposition settings under the ‘Morph & Consol’ tab seem to be overwritten. This may not be a big issue as the values may be manually adjusted and saved, but each time after going into the Bed constructor it seems to overwrite the Bed and Deposition settings under the ‘Morph & Consol’ tab.
- It seems that after using the ‘Inorganic Sediment Bed Constructor: Uniform Layer’, that sometimes it creates two additional bed layers.
Our findings are:
Q: When changing the bed thickness under ‘View Plan’ it initially seems to take it, but when saving the project multiple times, and then reopening, it somehow goes back to the previous values of bed thickness.
A: The sediment initialization flag (ISEDINT) was not updated in EE when you manually changed the bed. Your test case used specified a constant IC for the sediment bed and water column. So, when EE wrote the data, it did not update the sediment files since IC was constant. This was a bug and has been fixed in the latest EE7.0 and EE7.1.
Q: After setting the bed with the new ‘Inorganic Sediment Bed Constructor: Uniform Layer’ it seems to work fine, although the Bed and Deposition settings under the ‘Morph & Consol’ tab seem to be overwritten. This may not be a big issue as the values may be manually adjusted and saves, but each time after going into the Bed constructor it seems to overwrite the Bed and Deposition settings under the ‘Morph & Consol’ tab.
A: It is generally expected that creating a sediment bed is done in the early phases of generating a sediment model. That is why EE attempts to update the deposition porosity and cohesive void ratio to match the data entered in the Uniform Bed Generator. This is not a bug and is behaving as expected.
Q: It seems that after using the ‘Inorganic Sediment Bed Constructor: Uniform Layer’, that sometimes it creates two additional bed layers.
A: The bed constructor adds two layers of “empty” sediment layers to allow for deposition and layer addition. The “Max. Layer thickness” setting in the ‘Morph & Consol’ tab controls EFDC as to when it will create a new layer during deposition. If the top layer is already active and the thickness exceeds the maximum layer thickness, EFDC will just keep adding sediment to the top layer. This can result in a very thick layer, which is not a code problem but is a model configuration problem and should be avoided. This is expected behavior and is not a bug.