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Figure 7 Sediment Transport – Initial Conditions.
The Initialization of Sediment Beds
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There are several ways frame provides a number of options to build sediment beds in EFDC_Explorer as shown in the Initialization of Sediment Beds frame in Figure 7. The simplest option is to create a uniform bed which is described below. Other options include using a polygon digital surface model, using a sediment cores with grainsize, which is described below.
Sediment Bed Construction - Uniform Layers
To set up a simple horizontally uniform sediment bed for the model the user can open the Inorganic Sediment Bed Constructor: Uniform Layers form shown in Figure 8. This is access from selecting the Create Uniform Bed button shown in Figure 7, or from the main Sediment tab with Sediment Bed: Solids button. The Bed Constructor asks the user to input the number of layers, the number and types of sediments, and allows the user to specify the sediment fractions, thickness, and bulk densities for each layer. The user must still set the cohesive and non-cohesive erosion, and deposition parameters, but once the user finishes this option, the sediment bed configuration is ready for EFDC.
In the Bed Layer Settings frame the user may specify the number of bed layers and subsequently the thickness, porosity (thus void ratio) and mass distribution by layer. Once the sediment bed is generated the user can modify the sediment bed properties in ViewPlan, as needed. The layer configuration settings can be saved and later retrieved using the Save and the Load buttons in the Bed Properties Definitions frame.
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Figure 8 Uniform sediment bed generation tool.
It is generally expected that creating a sediment bed is done in the early phases of generating a sediment model. EE will attempt to update parameters in the Morphology & Consolidation tab such as the deposition porosity and cohesive void ratio to match the data entered in the Bed Constructor. This is not a bug and is behaving as expected.
Also, note that the Inorganic Sediment Bed Constructor: Uniform Layer tool adds two layers of "empty" sediment layers to allow for deposition and layer addition. The Maximum Layer Thickness setting in the Morphology & Consolidation tab controls when EFDC 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 bugsediments beds which are described in more detail in the Sediment Bed Construction section.