FIM library creation, Step 3, Delineating the extent of flood inundati

Figure 4. The hydraulic model takes each individual water-surface elevation (in this example, the 20-foot stream stage elevation from the previous figure), and overlays them onto a ground-surface elevation model (the brown, gridded base layer) to determine how far flooding would extend (the blue areas). The white lines represent the model’s perpendicular cross-sections.