A developer has recently purchased a 7 mi area of land north of Houston. She is interested in determining the impact that development will have on the hydrologic response of the area. There is one main channel running through the area and the length along it from the outlet to the divide is 6 mi. The aver- age slope in this area is 100 ft/mi. To determine the comparison hydrographs, a storm with duration of 3 hr will be used. Pre-development, the area is 40% wooded (good condition), 30% good con- dition meadow, and 30% cultivated land with conservation treatment. Post- development, the watershed will be 10% wooded (good condition), 5% good condition meadow, 30% cultivated land with conservation treatment, 30% residential with an average lot size of 1/8 acre, and 25% commercial area. The area has 40% soil type A and 60% soil type C. Using the SCS method of unit hydrograph construction and Excel to aid in your calculations and graphing, plot the resulting triangular hydro- graphs on the same graph for comparison and note the differences in a few short sentences. How does development affect the hydrograph? What do the resulting hydrographs tell you about the effects of high or low curve numbers?

A 200-acre urban drainage area consists of three different watershed areas: 60% single-family, 30% neighborhood businesses, and 10% playground area. If the time to concentration is 2.00 hours, determine the depth of gutters needed in the development area if each gutter is to accept 1% of the total volumetric flow. The slope along the roadway is 0.0005 ft/ft and a gutter cross-section as shown in Figure 4. State all assumptions applied.

The structure and enclosed paved plaza of the BMW Zentrum building, located in Greenville, SouthCarolina, may be approximated as a 70-m diametercircle. Flow path length may be approximatedas the average of the diameter and a half-circumference. The average surface slope ofthiscombinedfacility is approximately 5 percent.(a) Compute time of concentration using the FAA equation. (b) Rainfall intensity for Greenville County may be computed by the formula i = a/ (b + t.)°, usingcoefficients in the following table. What is the expected 25-year rainfall intensity? (c) Using the rational method, whatis the expected peak 25-year runoff from this facility? (d) What factors may contribute to the uncertainty of this runoff estimate?

8. Determine the mean runoff flow in cfs from a drainage area of 175 acres using the English equation for a 25-yr frequency in inches per hour in Nevada. The area is sloping at 2% and is covered with poor surface grass. The furthest point from the inlet is 72 meters.