Figure 10.19. 100-year flood design hydrographs.
The stage-discharge plot for the USGS gaging station on Rillito River near Tucson is shown in
Figure 10.20. In this plot, the gage height values from the flood observations have been
converted to equivalent stages at the present sites, based on the gage datum information given
below. The shifting of the stage-discharge relationships from early years to 1970 is also
indicated in this plot. For a given discharge the water-surface elevation drops about 3 ft from
the 1956-65 curve to the 1966 curve and drops another 2 ft to the 1974-1978 curve. The
decrease of the water surface elevation at this station is a result of the channel degradation
Figure 10.20. Stage-discharge plot for Rillito River near Tucson.