Water Levels

Water Levels option provides for a range of water depth derived parameters. The two main uses of this option are to plot water depths and water surface elevations. Some of the functions only use the water depths and bathymetry, which is always available, but some of the functions also require velocities to have been loaded. The graphic to the right shows some of the water level options grayed out because the velocities were not available. The following summarizes the other options:

Wet/Dry: Provides a two color display for wet cells (blue) and dry (gray). The wet/dry determination is made using the dry depth unless the Use Wet option is checked, in which case the wetting depth will be used. The areas and the numbers of wet/dry cells are reported.

Total Head: Displays the total head, water surface elevation + velocity head (v²/2g). Only available if the velocities have been loaded.

Overtopping: This displays the FEMA defined overtopping depth which is defined as: depth + velocity head (v²/2g). Only available if the velocities have been loaded.

Areal Ext (H): This option displays the FEMA velocity hazard level defined as depth * velocity head (v²/2g). The areas displayed and the areas computed are based on the computed hazard level over a specified minimum. The user can change the minimum level and EFDC_Explorer will recompute the areas and display the results.

Areal Ext (D): This option displays an inundation map and computes areas using a specified minimum depth and duration. The user can change the minimum depths and durations and EFDC_Explorer will recompute the areas and display the results. If a Compare model or a Compare model and a 3^rd model have been loaded (Section 6.3.1) then each model's results will be plotted in the order of Base, Compare then 3^rd. The colors displayed for each model can be changed by LMC'ing on the colored boxes beneath the Areal Ext checkboxes.

Figure 1 provides an example using a Base and a Compare model. Note the areas computed and displayed in the yellow information box.

Delta: Displays the differences in water surface elevations between the Base model and the Compare (i.e. Delta = Base-Compare). A Compare model, with depths, must be loaded for this option to be available.
The default is to use the "dry depth" as the cutoff between "wet" and "dry" cells. If Use Wet is checked then the "wet depth" water level will be used. Using the wet depth results in less cells being considered wet. This option is only applicable for models using wetting/drying options.

Figure 1 View Plan: Water Level showing Areal Extents based on depth-durations.