Investigating a new approach to enhance the discharge capacity of labyrinth weirs

Abstract Climate change has caused the inefficient operation of a significant number of old weirs to pass large discharges. Therefore, this study aims to increase the discharge capacity of the labyrinth weir. A new approach was proposed by modifying a labyrinth weir structure. The data were obtained from the quarter-round crest and different sidewall angles ranging from 8° to 35°. A conventional labyrinth weir was used for comparison. The results showed that the percentage of the notches area to sidewalls area of the weir (An/Aw) does not exceed 8%. Also, the percentage of the notches’ length to the total crest length (ΔL/Lc) does not exceed 32%. Also, the percentage of the notch depth to the sidewall depth (ΔP/P) does not exceed 30%. The other parameters are kept constant. These dimensionless terms provided a maximum compound discharge coefficient (Cdc) of 0.74. Also, the compound discharge coefficient initially increased at low water head ratios and decreased at higher values of water head ratios. The regression empirical equations were generated. A labyrinth weir with a larger sidewall angle was less efficient. The maximum increase in efficiency was 10% for a sidewall angle of 6° when compared to conventional labyrinth weirs.