The last tool to discuss is the link to the National Levee Database (NLD). Note: This option is only available to U.S. Army Corps of Engineers Employees, using an ACE-IT approved computer. If the user selects Import NLD from the RAS Mapper Tools menu, then a window will appear as shown in Figure 6-21. The user can select to query all the levees and floodwalls that are within the current view extents (the area shown on the screen when fully zoomed out), or within the view of selected map layers. Once the Query button is pressed, the software calls the NLD for all of its information. The NLD will send a list back to HEC-RAS and a window will appear on the screen with that list of levees/floodwalls (Figure 6-27).
The user then selects what information they want. Finally, the user presses the Download button, and then they will be asked to select a directory to store the data in. Once a directory is selected, the software will download a levee 3D centerline, a floodwall 3D centerline, and a polygon of the protected area for each of the levees listed in the window shown in Figure 6-27. Currently the information is stored in a ".gml" file format (Geospatial Markup Language). The next step for HEC-RAS in using this data is to automate the process of converting it into an HEC-RAS Lateral Structure to represent the levees and floodwalls, as well as use the protected area for 2D flow and/or storage area boundaries. This is not available in yet.
