These are the data that GeoFluv™ uses to calculate the drainage density for the subwatershed containing the channel in the Current Channel field above, and a display window that informs the user if discharge from additional area outside the GeoFluv Boundary is entering the subwatershed. These are not input fields, but real-time displays of the values being used in the GeoFluv™ design for the Current Channel. GeoFluv™ calculates these values from the subwatershed boundary it has built and the drainage pattern that the user sketched, and user-input additional area by the Channels tab's "Advanced . . ." button.
Valley Length (ft.) This value is the straight-line length of the valley (in feet in U.S. units), not the sinuous length of the channel.
Reach Area (ac.) This value is the area (in acres in U.S. units) draining water to that channel or channel reach.
Add'l Area (ac.) This field displays any additional area outside the GeoFluv™ boundary that is draining into the GeoFluv™ Current Channel. This could be contiguous undisturbed land or land that has already been reclaimed. The Channels tab's "Advanced . . ." button allows the user to add additional area.
Drainage Density (ft/ac) This value is the ratio of Valley Length to Reach Area in U.S. units of feet per acre, a convenient unit for this parameter in landform design work.
If the drainage density is within the variance that the user specified in the Design Natural Regrade dockable dialog box's Settings button, Natural Regrade Global Settings, "Target drainage density variance (%)", then the value will be highlighted in green; if the value is outside the user-specified variance it will be highlighted in red. A red warning can mean that the drainage density is too high or too low. If too high, the channel can be shortened or the Current Channel's subwatershed area increased. If the value is too low, the Current Channel can be lengthened, or a tributary channel can be drawn in the Current Channel subwatershed and then added using the Channels tab's Add button, or the subwatershed area can be decreased.
If the GeoFluv Boundary polyline or the valley bottom polylines are modified in the drawing, clicking on the Reread Valley Bottoms button will cause the above data to be updated.