CIV E 530 - OPEN-CHANNEL HYDRAULICS SPRING 2007 - MIDTERM 2 - SOLUTION

PROBLEM 4: COMPARISON BETWEEN DIRECT AND STANDARD STEP METHODS

1. i. Direct-step method is EASY.

   ii. Standard-step method is DIFFICULT.

2. i. Direct-step method is restricted to a PRISMATIC (usually artificial) channel.

   ii. Standard-step method is used for ANY-SHAPE (usually natural) channel.

3. i. Direct-step method ASSUMES FLOW DEPTH and calculates distance.

   ii. Standard-step method ASSUMES DISTANCE and calculates flow depth.

4. i. Direct-step method uses CHANNEL LENGTH as dependent variable.

   ii. Standard-step method uses FLOW DEPTH as dependent variable.

5. i. Direct-step method advances DIRECTLY.

   ii. Standard-step method advances BY ITERATION.

6. i. In the direct-step method accuracy increases with A SMALLER DEPTH INCREMENT.

   ii. In the standard-step method accuracy increases with MORE CROSS SECTIONS.

7. i. Direct-step method uses ONE TYPICAL cross section.

   ii. Standard-step method uses MANY DIFFERENT cross sections.

8. i. Direct-step method has MINIMAL data needs.

   ii. Standard-step method has EXTENSIVE data needs.

9. i. Direct-step method uses SPREAD SHEET.

   ii. Standard-step method uses HEC-RAS.

10. i. In the direct-step method an answer is ALWAYS POSSIBLE

    ii. In the standard-step method an answer is SOMETIMES NOT POSSIBLE.