A very useful feature in EFDC_Explorer is its ability to build the EFDC sediment files from a defined digital sediment model (DSM) that was generated by some third party package (e.g., Spatial Explorer). The DSM format requires a polygon followed by the layer thickness, bulk density, porosity and grain size distribution for each depth available (sediment depth intervals are based on data). More information on the data structure is available in Appendix B - Data Formats. EFDC_Explorer uses the DSM coupled with the number of size classes requested, the maximum size for each class, the number of sediment layers and the layer options (e.g., minimum layer thickness) to build the EFDC sediment files. The "Max (μm)" sediment diameters, one for each sediment class, are needed to break the sediment grainsize curves into ranges. These diameters are not the class diameters but represent the grainsize breakpoints whose geometric mean of the upper and lower limits is the corresponding sediment class' diameter.
When the user clicks on the Apply button after all the inputs have been provided, EFDC_Explorer generates the sediment map in memory and then writes out the files. The current sediment map (if any) will be replaced by the new one. It is recommended that the project be saved into a new subdirectory prior to implementing this option in order to save different versions of the sediment bed configurations.
Digital Sediment Model shows an example of a digital sediment model derived from sediment cores. The data contained grain size distributions by depth interval. The black diamond symbols show the locations of the cores. The plot shows the resulting depth averaged d50 grainsize.
The user also has many option for editing sediment cores within the ViewPlan form, described in detail in Sediment Bed.
Figure 1 A digital sediment model generated from sediment cores with grain size.