CIV E 445 - APPLIED HYDROLOGY SPRING 2011 - MIDTERM 2 - SOLUTION

PROBLEM 3: ESSAY QUESTIONS

1. 1 sq mi.

2. β = 1.667 = 5/3.

3. The four variables (or parameters) of the runoff curve number method are:
   
   
   1. Hydrologic soil group: A, B, C, D.

   2. Land use and treatment class: agricultural, urban, range, forest.

   3. Ground surface condition: poor, fair, good

   4. Antecedent Moisture Condition: I, II, III.

4. PRF = 484.

5. The NRCS Type II storm, which covers the internal continental U.S., excluding the Eastern seaboard, the coast of the Gulf of Mexico, and the Pacific Coast.

   

   

6. According to the Gumbel method, the return period of the mean annual flood is 2.33 years.

7. The correlation coefficient for this case would be zero.

8. Levees help protect rivers from overflowing their banks more frequently. However, disadvantages are:

   • they provide a false sense of security as floods increase in magnitude and frequency with upstream development,

   • when they fail, the results are usually catastrophic,

   • they starve the floodplain of nutrients, and

   • they produce the loss of "the sight of the river."

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