CIV E 445-APPLIED HYDROLOGY
SPRING 2006
SECOND MIDTERM
APRIL 10, 2006, 0730-0845

Name: _______________________ Red ID _________________ Grade: _______

Instructions: Closed book, closed notes. Use engineering paper. When you are finished, staple your work in sequence (1 to 3), and return this sheet with your work.

  1. (30%) An overland flow plane has the following characteristics:

    plane length L = 35 m;
    plane slope So = 0.008;
    Manning's n = 0.08;
    rainfall excess i = 55 mm/hr.

    Determine if the kinematic wave approximation is applicable to this set of overland flow conditions. Assume the exponent of the rating m = 5/3.

  2. (30%) A certain basin has the following 2-hr unit hydrograph (1 cm of rainfall), defined at hourly ordinates:

    Flow (m3/s):   0 5 15 30 60 70 60 55 45 35 25 15 5 0

    Calculate the flood hydrograph for the following effective storm pattern, defined at two 3-hr increments (6-hr total event duration).

    Time (hr):                                    3      6
    Effective rainfall (cm/hr):          2.0   4.0
    Total rainfall (cm):                   6.0  12.0

  3. (40%) Please answer briefly:

    1. What is a "small" catchment in a hydrologic sense?
    2. What channel property is primarily responsible for the flow being kinematic? What is the rule-of-thumb for kinematic flow?
    3. What are the four explicit variables (or parameters) in the runoff curve number methodology?
    4. Why is the rainfall-runoff problem well behaved?
    5. What is the lowest value of peak rate factor (PRF) (of the NRCS unit hydrograph) that has been documented in practice?
    6. Which SCS Type storm is the least intense? Where is it applicable?
    7. Why is the TR-55 method consistent with diffusion wave theory?
    8. According to the Gumbel method, what is the return period of the mean annual flood?