Determine the rainfall excess (i.e., runoff) resulting from the 10-yr, 24-hr rainfall for the watershed in Example 11.8. This amounts to completing steps 1, 2, and 3 of the design process described in Section 11.6.4 and elaborated in Example 11.6. Albemarle County, in western Virginia, receives 6.0 in. of rain in the 10-yr, 24-hr storm. Use a 2-hr time step.