1. Calculate peak runoff using the Rational Method for the drainage basin shown in Figure 11-15 for a 5-year storm. The basin is located in Pennsylvania, Region 1. 2. Calculate peak runoff using the...

1. Calculate peak runoff using the Rational Method for the drainage basin shown in Figure 11-15 for a 5-year storm. The basin is located in Pennsylvania, Region 1.

2. Calculate peak runoff using the NRCS Method for the watershed shown in Figure 11-17 for a 25-year storm. The watershed is located in western Pennsylvania. For an average stream cross section, use that in problem 4. Assume hydrologic soil group C.

problem 4

Determine time of concentration, tc, for use in the Rational Method for a drainage basin having a hydraulic path described as follows:

Overland flow: average grass, 80’ long, 2.5% average slope

Shallow concentrated flow: 450’ long, 4.8% average slope

Gutter flow: 200’ long, 1.9% average slope