Irrigation Sciences and Engineering

Irrigation Sciences and Engineering

Experimental investigation of the effect of single-row dentate baffles on the length of vertical drop structure

Document Type : Research Paper

Authors
Azadeh Jamshidi 1
Mahmood Shafai Bejestan 2
Mohammad Bahrami Yarahmadi 3
Mostafa Rahmanshahi 4
1 MSc student, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
2 Professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
3 Associate professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
4 Research assistant, University of Hong Kong, Hong Kong.
10.22055/jise.2025.49328.2156
Abstract
Among the hydraulic structures used in watershed management for sediment management in mountain streams are vertical weirs. In order to prevent bed erosion downstream of the structures a horizontal concrete slab is used which a hydraulic jump is formed. One of the important design parameters is to reduce the length of the hydraulic jump and, as a result, reduce the length of the slab for the economic efficiency of the project, which is the main goal of this research. The experiments were conducted in a rectangular flume 30 cm wide and 12 m long. The experiments in this research are divided into two groups with and without barriers. In the experiment with barriers, a row of dentated barriers with a height of five centimeters installed at a distance of 40 centimeters from the weir toe. In addition, in the experiment with barriers, a sill was used at the end of the weir. The height of the end sill was considered to be two, three, and four centimeters. The experiments were conducted under seven different flow conditions (Froude number in the range of 6.34 to 12.5 at the beginning of the jump). The results showed that the use of a discontinuous barrier with the end sill reduced the length of the hydraulic jump. Changing the height of the final sill did not have a significant effect on reducing the length of the hydraulic jump, with a maximum effect of about 5.7%. The results showed that the use of a discontinuous barrier at heights of 0.05, 0.08, and 0.11 times the height of the structure reduced the length of the hydraulic jump by 52, 53, and 57.7 percent, respectively.
Keywords
bed erosion
grade control structure
vertical drop structures
dam reservior
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Irrigation Sciences and Engineering
Volume 49, Issue 2
Summer 2026
Pages 1-14

  • Receive Date 28 March 2025
  • Revise Date 30 April 2025
  • Accept Date 24 May 2025
  • Publish Date 05 August 2026