Document Type : Research Paper

Authors

• Reza Hosseinzadeh Asl ¹
• Mehdi Yasi ²
• Masoud Bahreini Motlagh ³

¹ Ph.D. Student of Hydraulic Structures, Department of Irrigation and Reclamation Engineering, College of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran

² Associate Professor, Department of Irrigation and Reclamation Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.

³ Assistant Professor,Water Research Institute, Tehran, Iran

Abstract

Keywords

• Acoustic tomography
• Latian Dam
• Regularization
• Inverse problem
• Stratified flow velocity

20.1001.1.2008479.1402.54.6.1.1

Main Subjects

• سازه‌های آبی

Determining the layered flow velocity in the Latyan reservoir using acoustic tomography technology

EXTENDED ABSTRACT

Introduction

Acoustic tomography technology is an advanced method of remote sensing, which has been used and verified by many researchers in recent years to measure flow velocity and temperature in different water environments. Measuring the flow velocity in different layers of the dam reservoir, to monitor the state of sedimentation that is affected by the flow of the dam reservoir, and also to monitor the appropriate position of water intake or outlet of water consumption in power plants along the coast, thick flow of sediment in water bodies, infiltration of salinity in reservoirs and dams and the discharge of salt water from the deep outlets of the dams is necessary.

Methodology

The practical development of this technology in reservoirs of dams, especially Iranian dams, is necessary. Therefore, according to the importance of determining the flow velocity in different layers of the dam reservoir, in this research, with the help of acoustic tomography technology and solving the inverse problem using the adjusted Tikhonov method, the determination of the flow velocity in the different layers of the Latian dam reservoir was done. The innovation of this method can be called the investigation of the application of acoustic tomography technology in the reservoir of the dam to determine the speed of layered flow for the first time in Iran.

Results and Discussion

The basis of this method is to calculate and record the travel time of acoustic rays in the water environment, including the reservoir of the dam. In this research, two acoustic stations with mutual transmission with a frequency of 10 kHz were placed in the reservoir of Latian Dam on October 23, 2020. Five layers with a distance of ten meters in depth were selected. After ray tracing and identifying two or more rays with different travel times and while they pass through different depths of the studied area, the computing domain, which is the same perpendicular plane, is divided into several layers.

Conclusion

The results of solving the adjusted inverse problem showed that the maximum velocity of 0.0006 m/s occurs in the first layer (0 to 10 m depth). For the flow velocity of layers, two to five, 0.0003, 0.0001, 0.0002, 0.0001 m/s were calculated respectively, which according to the close to zero flow velocity of the dam reservoir at the time of data collection, the velocity of the flow was obtained with a relatively good approximation. According to the obtained results, the flow velocity in each layer was calculated to be around zero with a difference of 0.02 m/s. This value was consistent with the actual condition of the reservoir when the reservoir valves were closed. It is suggested that in future studies, data collection should be done when the water discharge valves are open so that the results can be compared with the results of this research.