CHAPTER 7 - WEIRS

4. Different Sharp or Thin-Plate Weir Types

The types of traditional fully contracted weirs commonly used and considered standard for measuring irrigation water are:

• Rectangular weirs
• V-notch weirs from 25 degrees to 100 degrees
• Cipolletti (trapezoidal) weirs

Common partially contracted weirs are:

• Partially contracted rectangular weirs
• Partially contracted 90-degree V-notch weirs

Equations for weirs determine discharge values used to produce tables for field use. However, users and designers must pay due respect to specific limits such as calibration range, velocity of approach, setting requirements, dimension tolerances, and operating techniques. A few weir tables are extended by measured data outside of equation limits.