FIM library creation, Step 2, modeling flood heights

Figure 3. This graph shows the results of a flood height model: the water-surface elevations of a fictional stream reach at different stream stages (heights). For example, when the USGS Streamgage measures a stream stage of 20 feet, the stream reach will be approximately 825 feet above sea level at its western boundary and 805 feet above sea level at its eastern boundary (the upstream end is typically higher than the downstream end, indicating a downstream direction of flow).