1. Basic Hydraulics: Solids Transport

2. What is sediment? Matter that settles to the bottom of a liquid
Matter transported by water or wind
May be particles that are derived from rocks, biological materials, or chemical precipitates
Highway sediments may be a mix of materials, including pavement dust, natural soils, vehicle rust particles, tire dust particles.

3. Soil erosion (scour)
Caused by impact and dislodgment of individual soil particles by rain drop impact.
Caused by flow of water over soil surfaces.
Caused by movement of water in channel systems.

4. Erosion and transport mechanisms
Rill and sheet erosion
Gully erosion
Bed and bank erosion
Suspended material transport
Bed material transport
Wash load transport
Australian Dept. of Environment
Rill erosion progressing to gullies

5. Suspended material transport
Channels accumulate sediment from sheet/rill and gully erosion
Lighter sediment carried as suspended material
Heavier materials settle to bottom, added to material eroded from banks and bed

6. Bed material transport
Stream bed load is part of total sediment load that moves along bottom of channel
Sediment particles roll, bounce, or slide along bottom
When stream has ability to re-suspend, some of particles will move
When it loses ability to carry particles in suspension, they will drop out again
Depends on local stream velocity and settling velocity of individual particles

7. Wash material transport
Material that tends to flow through a reach without significant interaction with the bed
Material is usually coarse sand, smaller in size

8. Solids transport – bed & suspended load
El Paso District

9. Solids transport – bed & suspended load
Terrell County

10. Solids transport – debris
Also have bouyant solids (debris) in the flow