A 150-acre forested watershed with a time of concentration of 90 min will soon be developed with

Question:

A 150-acre forested watershed with a time of concentration of 90 min will soon be developed with the following land uses: 60 acres of single-family homes, 40 acres of apartments, and the rest in native forest. After development, the longest flow path is 5,600 feet. A 100-foot sheet flow segment passes through woods with light underbrush on a 2-percent slope. A 1,200-ft segment of shallow concentrated flow occurs next over an unpaved area on a 1-percent slope. Channel flow occurs over the remaining distance on a slope of 0.5 percent in a stony natural stream. A typical cross section of the stream has 18 ft2 of flow area and 24 ft of wetted perimeter. The 2-yr, 24-hr precipitation is 3.8 in. Using the IDF curve in Figure 11.26, determine the 25-yr peak discharge before and after development using the rational equation.