Sediment and Sedimentation Flashcards
It is a naturally occurring material that is broken down by processed of weathering and erosion and is subsequently transported by the action of wind, water, or ice and/or by the force of gravity acting on the particle itself
Sediment
Sources of sedimentation
Land clearing
Unsealed roads
In-stream disturbance
Agricultural activity
Mining
Other activities
Characteristics of sediments (A. Particle classes)
Primarily clay, primarily silt, small aggregate, large aggregate, primary sand
Characteristics of sediments (B. At detachment)
Distribution of classes function of texture
Diameter of small and large aggregates function of texture
Characteristics of sediments (C. After deposition)
Sediment enriched in fines
Flowing water transports sediments as:
Bedload
Suspended load
Wash load
Bed material load
grains rolling, sliding, and/or saltating in frequent or continuous contact with bed
bedload
it is the transport of sediments by hopping and bouncing along the channel bed
saltation
grains in suspension above the bed for extended periods of time
suspended load
that part of the suspended load that is not found in the bed
wash load
the fine fraction which is mostly in suspension
wash load
the coarse fraction normally found in the bed
bed material load
concentration of sediments in a stream ____ with distance up from the bed
decreases
at any given point, the upward flow of water will have _____ than the downward flow
higher sediment concentration
Under steady state condition, the rate of sediment upward flow due to turbulent diffusion is ______ to the downward flow rate due to the ________
equal, settling action of gravity
the common methods of estimating the sediment discharges of rivers include:
- Actual monitoring of the sediment load through sediment sampling
- Using sediment discharge formulas
- Other sampling technique
can be depth-integrated or point sampling (taken at fixed depth from the river bottom)
sediment sampling
ratio of the dry weight of sediment to total weight of the sample, expressed in parts per million or mg per liter
sediment concentration
also used to estimate the sediment loads on days when no measurements are available
rating curve (relating suspended-sediment discharge and water discharge)
what is the formula in getting sediment discharge per unit channel
see pdf for details
formula in getting the velocity at any depth
see pdf for details
sediment discharge formulas
Meyer-Peter
Schoklitsch
Shields
duBoys
Einstein-Brown
Kalinske
the sediment carrying capacity of a stream is proportional to the water discharge raised to a certain power
skl
the rate at which the capacity of a reservoir is reduced by sedimentation depends on:
*the quantity of sediment flow
*the percentage of this inflow trapped in the reservoir
*the density of the deposited sediment
the volume occupied by the sediment in the reservoir will depend on:
the specific weight of the deposited material
the exceptionally high sedimentation rate in the mountainous Agno RIver Watershed in the country has affected dam operations on the Ambuklao and Binga reservoirs
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