CIV E 632-COMPUTATIONAL HYDRAULICS AND HYDROLOGY
SPRING 2008
FINAL EXAM
WEDNESDAY, MAY 14, 2008, 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 all 11 questions (one bonus question).

  1. Why does the diffusion wave model of catchment dynamics provide grid independence for a wide range of grid resolutions, while the kinematic wave model (the Li method) does not?

  2. Compare the distributed method of runoff generation (overland flow) with the lumped method (unit hydrograph) in terms of their advantages and disadvantages, in theory and in practice.

  3. 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?

  4. 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?

  5. Why is it often necessary to artificially extend the channel reach in dynamic wave modeling? What would happen if a unique rating curve (a kinematic boundary condition) is specified at the downstream boundary? Why?

  6. 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?

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

  8. Why do dam-breach flood wave peaks eventually reach the same value at a certain distance downstream?

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

  10. What two types of boundary conditions arise in two-dimensional groundwater modeling? Explain.

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