How UVP-DUO Helps in Understanding Sedimentary Morphodynamics of Turbidity Currents and River Flows

19 June 2024 by
How UVP-DUO Helps in Understanding Sedimentary Morphodynamics of Turbidity Currents and River Flows
Met-Flow SA

Summary of the Experiment

The study aimed to understand and characterize sediment transport in turbidity currents within natural and artificial reservoirs. The experiments were conducted in a unidirectional channel measuring 5.35 m in length, 0.30 m in width, and 0.38 m in height, with a 3° slope. Fine kaolin sediment (dm = 23 µm) was used, injected at a constant discharge of 2 liters/sec for 30 minutes per experiment. Two series were conducted: a high concentration series (Cv = 2.7%) with three experiments, and a low concentration series (Cv = 1.25%) with four experiments. Measurements were taken 3.50 m from the injection point, assessing velocity and sediment concentration.


The UVP-DUO played a crucial role in measuring flow velocities and sediment transport characteristics. A 2 MHz ultrasound velocity probe was installed at a 30° angle from horizontal, 3.50 m from the injection point. Key parameters included a velocity range of 0.09 to 1.48 m/s, a velocity resolution of 49 mm/s, a distance range of 0.3 m, and a spatial resolution of 193 mm. The data acquisition time was set at 3 ms, with a sampling frequency of 4170 Hz. These measurements enabled precise monitoring of the flow dynamics and sediment transport processes.

Result of the Experiment 

The experiment revealed distinct behaviors in the high and low concentration series. High concentration currents showed acceleration, increased thickness, and dilution over time. Low concentration currents displayed retraction, thinning, and development of a basal layer. Both series achieved dynamic equilibrium between flow and bed after approximately 60 minutes, with stable hydrodynamic parameters: Richardson number (Ri ≈ 0.41) and resistance coefficient (cf ≈ 0.015).

The UVP-DUO's high precision and resolution were critical in capturing the detailed flow velocity profiles. This data was essential for calculating bed shear stress and understanding sediment transport mechanisms. The results indicated small wrinkles on the flat bed, evolving into straight-crested and undulatory ripples with amplitudes of 3-9 mm and wavelengths of 70-110 mm. Empirical models showed good agreement with observed ripple lengths but overestimated amplitudes.

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