Sediment Transport

Question 1

The process of eroding sediment from one place, transporting it in the flow and depositing it in another place.

Answer 1

Sediment Transport

Question 2

Occurs when the shear stress applied on
the sediment bed exceeds the critical shear stress

Answer 2

Erosion

Question 3

It takes place when the transport capacity of the flow is exceeded.

Answer 3

Deposition

Question 4

(4) Basic sediment process

Answer 4

Resuspension
Transport
Settling
Consolidation & compaction

Question 5

Sediment process is dependent on

Answer 5

1)Flow hydrodynamic conditions
2) Sediment Properties (size, shape, density, composition)

Question 6

It is most fundamental property
governing the motion of the
sediment particles in water.

Answer 6

Particle Settling

Question 7

Defined as the terminal velocity at which a single particle falls through quiescent water and depends on the particle’s size, shape, and density along with the water’s viscosity and density.

Answer 7

Settling Velocity

Question 8

True/False

For Sediment Transport Modeling, the settling velocity of particles and their resistance to resuspension under shear
stress are the most significant.

Answer 8

True

Question 9

True/False

PARTICLE SETTLING CHARACTERISTICS vary as they respond to hydrodynamic conditions in the water body.

Answer 9

True

Question 10

True/False

Once near the bottom, DEPOSITION governs their removal from the water column.

Answer 10

True

Question 11

2 major mechanisms for sediment transport

Answer 11

Currents & Wind waves

Question 12

True/False

Sediment transport is significantly
influenced by the instability of the near-bed flows.

Answer 12

True

Question 13

True/False

Sediment is moved either only suspended or bed load.

Answer 13

False (and/or)

Question 14

Calculation of total sediment load

Answer 14

Suspended load + Bed load

Question 15

It is the portion of the sediment load that is transported in suspension in the water column which includes:
sediments resuspended from the bed and wash load brought from upstream.

Answer 15

Suspended Load

Question 16

It is used to analyze contaminant transport since contaminants are often attached to and transported by sediments in suspension.

Answer 16

Total Suspended Load

Question 17

It has relatively fine material in near-permanent suspension
that is transported through the system without deposition.

Answer 17

Wash Load

Question 18

It is comprised of particle sizes finer than those found in the
bed.

Answer 18

Wash Load

Question 19

True/False
Cohesive sediments can be transported as suspend load and bed load.

Answer 19

False

Question 20

True/False

Cohesive sediments can be transported as suspended and or bed load.

Answer 20

False (only as suspended load)

Question 21

True/False

Cohesive sediments can be transported as suspended and or bed load.

Answer 21

False (only as suspended load)

Question 22

True/False
Non-cohesive sediment can only be transported as bed load.

Answer 22

False (both suspended and bed load)

Question 23

The 2 mechanism of transporting cohesive as suspend load:

Answer 23

Advection
Dispersion

Question 24

It is a mechanism where the cohesive sediment is carried with the ambient water at the flow velocity.

Answer 24

Advection

Question 25

It is a mechanism of transport where cohesive sediment is moved from an area of high to low sediment concentration.

Answer 25

Dispersion

Question 26

It is a type of load where it is comprised of particles that move on/ near the bead by Saltation, rolling, or slid8ng in the bed layer.

Answer 26

Bed Load

Question 27

True/False The bed load movement occurs intermittently in a thick layer; on or in close contact with the bed.

Answer 27

False (thin)

Question 28

It is a process by which individual sediment grains make isolated or serial jumps along the bed?

Answer 28

Saltation

Question 29

t provides a transition from bed-load transport that takes place immediately above the bed to suspended-load transport that takes place in the overlying water column.

Answer 29

Saltation

Question 30

It is defined as the frictional force per unit of bed area exerted on it by the flowing water.

Answer 30

Shear Stress

Question 31

It is an important factor in the movement of bed material and is a useful parameter in describing sediment transport as well as erosion and deposition.

Answer 31

Shear Stress

Question 32

True/False Shear stress is exerted on the bed when water flows over it, as either steady flow or oscillatory flow under tides and waves.

Answer 32

True

Question 33

True/False Shear stress moves bed particles in a sliding motion downstream.

Answer 33

False (rolling)

Question 34

True/False If the shear stress is greater than the critical shear stress, only a fraction of the suspended material will be deposited.

Answer 34

True (higher shear stress-sediment go up)

Question 35

True/False If the shear stress is less than the critical shear stress, suspended sediment will be deposited on bed gradually.

Answer 35

True

Question 36

(3) bottom shear stress mechanism vary

Answer 36

Temperature Topography Salinity

Question 37

3 Bottom shear stress mechanism vary

Answer 37

Temperature Topography Salinity

Question 38

3 Bottom shear stress mechanism vary

Answer 38

Temperature Topography Salinity

Question 39

4 Sources of sediment transport

Answer 39

Point discharges Land surface runoff Bank erosion Bed scour

Question 40

4 Predominant factors responsible for sediment transport

Answer 40

Currents Winds Inflows Tides (in estuaries and coastal waters)

Question 41

Major Mechanism of sediment transport

Answer 41

Currents & Waves

Question 42

A major mechanism dominant in rivers.

Answer 42

Currents

Question 43

A major mechanism that is dominant in lakes, especially during storm.

Answer 43

Wind wave

Question 44

The two mechanism that is dominant estuaries.

Answer 44

Wind & tidal waves

Question 45

True/False In Steps 1 and 2, the predominant mode of transport is sediment grains moving along the bottom in the form of bed load. Particle movement begins as a sliding or rolling motion.

Answer 45

True

Question 46

True/False In Step 3, some particles also may move above the bed surface through saltation. These movements result in frequent contact of the moving particles with the bed and are transported as bed load.

Answer 46

True

Question 47

In Step 4, particles begin to be suspended and are subject to _______ forces as the flow velocity and shear stress increase. Particles are thrown up into suspension and are transported as suspended load.

Answer 47

turbulent

Question 48

(2) Difficult to separately identify the phase of resuspension and deposition in natural waterbodies

Answer 48

Resuspension & Deposition

Question 49

It determined the critical shear stress for erosion as a function of depth and the erosion rate as a function of both shear stress and depth. (Designed by McNeil)

Answer 49

SEDflume

Question 50

It measures the erosion of sediments at high shear stresses and with sediment depth.

Answer 50

SEDflume

Question 51

It is controlled primarily by BOTTOM SHEAR STRESS and also SITE-SPECIFIC BED PROPERTIES for erosion rates and scour depths.

Answer 51

Sediment Resuspension

Question 52

True/False Sediment on the bed will be eroded and transported when the bottom shear stress EXCEEDS A CRITICAL VALUE.

Answer 52

True

Question 53

[Sediment RESUSPENSION] The Immersed particle weight is the main stabilizing force.

Answer 53

Non-cohesive sediment

Question 54

True/False [Sediment RESUSPENSION] For sediment with bulk density close to the water density, the main forces are interparticle adhesion and organic binding.

Answer 54

True

Question 55

True/False [Sediment RESUSPENSION] Beds are layered with density and shea strength decreasing downward.

Answer 55

False (increasing)

Question 56

True/False Sediments move whenever the shear stress caused by water flow and wind waves REACHES A CRITICAL SHEAR STRESS FOR RESUSPENSION that is EQUAL TO THE SHEAR STRENGTH "HOLDING" the sediment to the bed.

Answer 56

True

Question 57

A process by which suspended sediments LEAVE the water column, either temporarily or permanently, and become part of the bottom sediments.

Answer 57

Sediment Deposition

Question 58

True/False [Sediment DEPOSITION] With non-cohesive sediment, the critical shear stress is only slightly less than that for erosion. Particles settle to the bed almost as soon as the shear stress is too small to erode it.

Answer 58

True

Question 59

True/False [Sediment DEPOSITION] With cohesive sediment, critical shear can be much greater than that for erosion.

Answer 59

False (smaller)

Question 60

It can be estimated as the product of the settling velocity and the probability of deposition on contact with the bed, which is 0 for very turbulent systems and 1 for stagnant ponds.

Answer 60

Deposition Rate

Question 61

True/False For depostion, particles must overcome RESISTANCES due to: Turbulence in the Water Column Thin Viscous Sublayer at the Interface Chemical or Biological Activity at the Bottom

Answer 61

True

Question 62

True/False Probability of deposition depends on: Bottom Shear Stress Suspended Sediment Size Cohesiveness of the Sediment

Answer 62

True

Question 63

True/False Once in SUSPENSION, sediments will settle out at a rate determined by the sediment concentration, the settling velocity, and the turbulence intensity.

Answer 63

True