CIV E 632-COMPUTATIONAL HYDRAULICS AND HYDROLOGY
SPRING 2014
FINAL EXAM
WEDNESDAY, MAY 14, 2014, 1900-2100

Name: ______________________ S.S. No. ________________ Grade: _______

Instructions: Closed book, closed notes. Use engineering paper. When you are finished, staple your work in sequence, and return this sheet with your work. Answer 10 questions.

  1. Explain the method of cascade of linear reservoirs. For what applications is it recommended?

  2. In implicit dynamic wave modeling with HEC-RAS: How is the downstream boundary condition specified to increase accuracy?

  3. What is the difference between the Hayami, Dooge, and Dooge et al. formulations for hydraulic diffusivity to use in the modeling of flood propagation using the convection-diffusion equation? What is the role of the Vedernikov number in the hydraulic diffusivity?

  4. Explain the possible range of β, the exponent of the rating Q = αAβ, in open-channel and free-surface flow.

  5. What two kinds of errors arise in numerical modeling? Explain which one is related to stability, and which one to convergence. Why is numerical modeling a compromise between stability and convergence?

  6. Why is a second-order numerical scheme not necessarily better than a first-order scheme? What artifice is usually resorted to in order to provide stability at the expense of convergence?

  7. What is the effect of the weighting factor θ in implicit numerical modeling using the Preissmann scheme. What physical and numerical factors affect model convergence?

  8. Why does the Muskingum-Cunge method work best at Courant number equal to 1? What happens for Courant greater than 1? For Courant less than 1?

  9. What is the value of β for an inherently stable channel? In practice, what value maximum value of β will guarantee stability, even though the cross section may not be inherently stable?

  10. Do sedimentation bed transients (channel bottom perturbations) in alluvial rivers travel upstream or downstream? Explain.

  11. Why is it better to use an explicit scheme rather than an implicit scheme in two-dimensional groundwater modeling? Explain.

  12. Should two-dimensional flow to a side river embayment convect (go straight into) or circulate (turn around)? Explain.