Plan sediment movement with clear hydraulic inputs and quick results. Support culvert and channel decisions. Export clean tables for site reviews and project records.
| Flow Rate | Width | Depth | Slope | d50 | Shields | Solid Bedload | Tonnes/Day |
|---|---|---|---|---|---|---|---|
| 4.00 m3/s | 4.00 m | 0.80 m | 0.0020 | 12.00 mm | 0.0577 | 0.00018784 m3/s | 43.0084 |
This tool uses a rectangular channel assumption and a Meyer-Peter Muller style bedload relation for coarse sediment movement.
Flow area: A = b × h
Wetted perimeter: P = b + 2h
Hydraulic radius: R = A / P
Boundary shear stress: τ = ρ × g × R × S
Shields parameter: θ = τ / [ (ρs − ρ) × g × d50 ]
Unit bedload rate: qb = α × 8 × √[(s − 1) × g × d50³] × (θ − θc)1.5
Total solid bedload: Qb = qb × b
Bulk deposit rate: Qbulk = Qb / (1 − n)
Where s = ρs / ρ, α is the transport factor, and n is porosity.
1. Enter the channel flow rate in cubic meters per second.
2. Add the active channel width and average flow depth.
3. Enter the bed slope as a decimal value.
4. Provide the median grain size d50 in millimeters.
5. Review or adjust water density, sediment density, critical Shields value, porosity, and transport factor.
6. Click the calculate button to see the result section above the form.
7. Download the result as CSV for spreadsheets or PDF for project records.
8. Compare the output with field observations, design criteria, and site risk tolerance.
Bedload transport affects many construction decisions. Gravel and coarse sand can move along the channel bed during storms or controlled discharges. That movement can reduce culvert capacity, alter channel shape, and increase local scour. It can also bury outlets, expose geotextiles, or overload sediment traps. A practical estimate helps teams judge erosion risk early. It also supports sizing checks for temporary drainage, site channels, diversion ditches, and energy dissipation works.
This calculator focuses on coarse material that rolls, slides, or hops near the bed. It does not target fine suspended sediment. The tool uses flow rate, width, depth, slope, grain size, and density inputs to estimate shear stress and a Shields mobility value. Those outputs show whether the bed is likely to move. When the mobility threshold is exceeded, the tool estimates unit bedload, total solid transport, bulk deposit rate, and daily mass movement.
Construction planners can use the output during channel lining reviews, temporary works checks, and sediment management planning. It can support decisions on riprap transitions, check structures, outlet protection, and maintenance intervals. The result is also useful when comparing alternative widths or slopes. A lower slope may reduce mobility. A larger stone size may reduce transport. Those comparisons help teams build safer drainage details and more durable conveyance paths.
Every bedload formula has limits. Natural channels are irregular. Grain sizes are mixed. Flow depth changes across the section. Backwater, armoring, and unsteady runoff can shift actual transport rates. Treat this tool as a design screening aid, not a substitute for field data or full hydraulic modeling. Use survey information, sediment sampling, and site observations to confirm assumptions. When risk is high, combine this estimate with professional review and project specific guidance.
Bedload transport is the movement of coarse sediment along the channel bed. Particles usually roll, slide, or hop. It differs from suspended load, which travels within the water column.
It uses a Meyer-Peter Muller style approach with Shields based mobility. The method is useful for coarse sediment screening in open channels and construction drainage studies.
If the computed Shields parameter does not exceed the critical threshold, the tool reports no predicted transport. That means the bed is below the selected movement criterion.
Yes. It is useful for preliminary checks on culvert outlets, lined ditches, temporary channels, and diversion paths. Confirm the result with site geometry and observed sediment conditions.
d50 is the median grain size. Half the sampled sediment is smaller, and half is larger. It is commonly used to represent the active bed material.
Porosity helps convert solid transport volume into bulk deposit volume. That is useful when estimating storage, cleanout needs, or the loose volume of moved bed material.
Use the default only as a starting point. You may adjust it when local guidance, calibration data, or project standards suggest a different mobility threshold for the bed material.
No. It is best used for screening and comparison. Final design should also consider field data, channel irregularity, gradation, roughness changes, and event specific hydraulics.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.