CIV E 632-COMPUTATIONAL HYDRAULICS AND HYDROLOGY
SPRING 2006
FINAL EXAM
WEDNESDAY, MAY 17, 2004, 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 only 10 questions.

  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 is topology in the context of catchment modeling? What is a generalized topological structure?

  4. 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?

  5. 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?

  6. 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?

  7. 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?

  8. Compare the tradeoffs between explicit and implicit schemes. Which one is better? Why?

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

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

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

  12. Describe the role of convective inertia and bottom friction in the numerical specification of circulation in two-dimensional depth-averaged flow.