CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2013
LAB No. 4 DEMONSTRATION:  BROAD-CRESTED WEIR

Objective: To demonstrate the principles of the broad-crested weir.

  1. Critical depth above weir:  D = (2/3) H

  2. Theoretical formulas for discharge, based on critical flow in the vicinity of the weir (U.S. Customary units):

    Q1 = (2/3) H [ (2/3) gH ]1/2 L = 3.087 L H3/2         [1]

    Q2 = (g D3)1/2 L = 5.67 L D3/2         [2]

  3. With the flume setup running at a given discharge, measure:

    1. Head H (ft)

    2. Flume width L (ft)

  4. Calculate:

    1. Discharge Q1 based on Equation 1

    2. Discharge Q2 based on Equation 2

  5. Compare Q1 with Q2.

  6. Write a brief report summarizing the findings.