海岸动力学英文PPT课件Coastal Hydrodynam(3)

and littoral drift, are distribution of grain size,
shape, roundness, mineral composition,
porosity, permeability, etc. Among them, grain
size distribution and mineral composition are
mineral composition and spatial distribution
of gravel can be used. For that purpose, coastal
topography data and information on the
depositional sediment state in the vicinity of
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Chapter 5
The observation of how the bed material grains are distributed along a beach profile is quite interesting for the purpose of understanding the influence of waves and currents on sediment movement.
coastal structures such as breakwaters, jetties,
and groins are taken as valuable indices for this
judgment.
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Chapter 5
2. Modes of movement
Coastal sediment particles are transported by the
generally more important.
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Chapter 5
Grain size distribution can be studied by sieve
analysis of sampled material. It is known to be
expressible through a log-normal distribution
vicinity of the beach, ➢ the debris from nearby coastal cliffs.
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Chapter 5
The sediment physical properties, which must
be known in order to investigate coastal change
Coastal Hydrodynamics
Chapter 5 COASTAL SEDIMENT
Stating characteristics of coastal sediment Stating bed load transport under wave action Stating suspended sediment transport under wave action Stating longshore sediment transport
influence of waves and neFra Baidu bibliotekrshore currents in the
onshore or offshore directions, or parallel to the
shoreline. There are two modes of sediment
movement: suspended sediment movement and
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§5.1 Characteristics of Coastal Sediment 1. Physical properties of coastal sediment 2. Modes of coastal sediment movement 3. Threshold of coastal sediment motion
bed load movement.
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Chapter 5
Incoming waves reach a certain water depth (offshore region), then bed material sand particles there begin oscillatory motion due to wave action. In a slightly more shallow area, waves produce a net motion of sand particles in the onshore or offshore direction. The interesting feature in this region is the generation of sand ripples, which seem to have a strong influence on sediment movement.
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Chapter 5
In order to determine the source of littoral drift,
the predominant direction of littoral transport
sometimes must be predicted. In such cases, the
function. The distribution of grain size d itself
is not a normal distribution, but the distribution
of logd can be described by a normal distribution
curve.
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Chapter 5
1. Physical properties
Beach materials mainly consist of ➢ the sand and gravel transported by rivers, ➢ the sand composing dunes located in the