The Flow Boundary Condition Editor is shown in Figure 1. For flow BC's the Flow Assignment frame has several useful functions. The Edit button to allow the user to edit the associated time series. The All buttons next to the fields in this subframe allow the user to quickly assign all the boundary cells in the current group to the parameter specified in the adjacent field. For example, pressing the All next to the Flow Table field shown in Figure 1 would set the flow series number for all cells in the US Flow flow group to the current Flood Flow table settings.
If the user has an input flow series for a river that requires distributing the river flow across several cells, the single time series of flow can be specified in the Flow Table. The Factor can then be set to split the flow appropriately among the cells. The Dist Factors button automatically sets the Factor based on each cell volume.
A constant inflow can also be distributed in a similar manner by using the Distribute Flow button. The user sets a value in the Constant Flow field. This constant flow will then be added to the time series for the flow table for this cell.
The Flow Assignment frame also provides the Apply Flow Files button which is quite a specialized feature. This feature is predominantly used in wetting and drying models and is designed to handle the case where there is flow coming into a river with a flood plain. During low flow conditions the flow will go only into the channel, whereas in high flow conditions the flow should be distributed across the flood plain. Selecting the Apply Flow Files button displays a form allowing the user to browse to Flow and Head files. These are a flow table for total flow and a rating curve respectively. In this way the user can import flow with the flow files to build a cell by cell variable inflow series. This is based on the initial conditions for the cell volume.
The user interface for boundary conditions has a uniquely designed editor with drop down menus for concentration table assignment to flow tables. When the user selects Flow Table as shown in Figure 1, they can use drop down menu items to link flow tables with concentration tables. As with earlier versions of EFDC_Explorer, the concentrations specified in the Constant Concentrations frame are only used with constant flows. Specifying a constant salinity concentration of 5 ppt in the Constant Concentrations frame but with zero constant flow, even if the boundary has flows assigned via a time series, the salinity input to the model will be zero. If using a time series for flows, the user must use a time series to assign salinity, even if they are constant. Note that the water column concentration settings, for both time series and constant, are fixed for all cells for the same group.
The Flow Multiplier Switch subframe provides a drop down box with a number of options, from normal inflow to various lateral inflow/outflow options. Constant concentrations and time variable Concentration Tables may also be edited from this frame.
Figure 1 Boundary Condition Settings – Flow Boundary.