Compute the 100-year return period discharge rate from the watershed below before and afte...

Compute the 100-year return period discharge rate from the watershed below before and after development using the following sequence of hydrologic operations:

1. Compute hydrograph from subbasin 301

2. Compute and add hydrograph subbasin 302

3. Route hydrograph through stream reach 701

4. Compute and add hydrograph subbasin 303

5. Compute and add hydrograph subbasin 304

6. Compute and add hydrograph subbasin 305

7. Route hydrograph through stream reach 702

8. Compute and add hydrograph subbasin 306

9. Store hydrograph 0

The 100-year rainfall intensity equation for the area is

Use a 24-hour duration storm with dt = 10 minutes and an initial rainfall abstraction of 1.0 inch (25.4 mm) before development and 0.5 inches (12.7 mm) after develop­ment. The volumetric soil moisture content of the soil is 0.25. Subbasin characteris­tics are listed below.

The channel has a slope of 0.003, with a channel Manning "it" value of 0.08 and an over-bank "n" value of 0.12. After development, "n" values will be 0.04 and 0.06. respectively. Use the following cross-sections for routing with NSEC = 80 and PERQ = 2.

Problem 10.32  Watershed maps.