The user defines a three-dimensional surface file that GeoFluv™ will use as the reference surface from which the fluvial geomorphic surface will be designed. This surface file could be an existing Approximate Original Contour map, a pre-disturbance map, or any other surface from which the user wants to begin the design.
When the user clicks on the Surface for Elevations button, the Use Existing TIN or Create New TIN? Pop-up dialog box appears to give the user the options, by clicking on radio buttons, for entering a 3-D surface file. The user can type the file name into the File Name field or browse for the file by left-clicking the Browse button to the right of the File Name field. Left-clicking the browse button will open another dialog box that will display file selections and the directory path. The user can search for the surface file in various directories and left-click the Open button when the desired 3-D surface file is found.When the Surface for Elevations file has been accepted, the file name is listed below the Surface for Elevations button, and GeoFluv™ reads the head and base level elevations from the Surface for Elevations file for the main channel that the user has sketched and displays these elevations in the "Data for main channel:" fields above the Surface for Elevations button. GeoFluv™ designs the main channel from this information and the settings on the Channels tab. The elevation at the heads of all other channels have their defaults set by the Surface for Elevations. The elevations along the GeoFluv Boundary are also set from this surface. This in turn sets the elevations of the main ridges and subridges and subridge valleys that intersect the GeoFluv Boundary.