The potential rate of bed-load transport

Area of Science:

• Earth and Environmental Sciences
• Geomorphology
• Hydrology

Background:

• Bed-load transport is a key geomorphic process in rivers.
• Understanding transport limits is crucial for river management and modeling.
• Existing formulations may not fully capture particle-size-dependent transport limits.

Purpose of the Study:

• To confirm and quantify an upper, particle-size-dependent limit to bed-load transport efficiency.
• To develop a practical formula for estimating potential bed-load transport rates in gravel-bed rivers.

Main Methods:

• Averaging field measurements from three rivers with high sediment availability.
• Analyzing laboratory experimental data representing high transport rates.
• Developing a regression relation from six diverse datasets.
• Incorporating the relation into Bagnold's classic bed-load transport formulation.

Main Results:

• Confirmed an upper limit to bed-load transport efficiency, dependent on median particle size (D50).
• Derived a new empirical formula: i(b) = omega [0.0115.D(50)(-0.51)]/0.63.
• Validated the formula against two independent river datasets, showing good correspondence (+/-10%).

Conclusions:

• The derived formula provides a straightforward method to estimate potential bed-load transport rates in gravel-bed rivers.
• This empirical limit is applicable when sediment supply and availability are not limiting factors.
• The findings enhance the predictive capability for sediment transport dynamics in river systems.