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Chapter 3
Sédiment Transport
3.1 Introduction
In the Coastal and nearshore zones, where shore processes begin, there is
mixing, sorting and transportation of sédiments as well as run-off from the
land. Waves, winds and currents mould the shorelines of the world and
their interaction with the land and its run off détermines the configuration
of coastlines and the adjacent bathymetry. Man’s intervention into the natural processes taking place in the Coastal zone also has an impact on the
shoreline. These are in the form of discharges into the océan, thermal and
radioactive pollution, dredging, Coastal construction, mining and poaching.
There are many factors the affect the processes that take place in the
nearshore zone. The most importance are: degree of exposure to waves and
currents, supply of sédiments and run off to the coasts, topography of the
continental shelf and the adjacent coast and tidal range and the intensity
of the tidal current and Coastal climate.
Of ail these factors, waves play a prédominant rôle in the nearshore
processes.
3.2 Modes of Sédiment Transport
3.2.1 General
Sédiments are considered to be transported by one of the two major modes
i.e., either as bed load or suspended load. When the sédiments are transported along the seabed either by rolling, sliding or bounding it is said to
be bed load sédiment transport. When the transport rates are high, which
involving movement of bed materials in several layers with ail in contact
with one another are said to be a sheet flow. The transport by hopping
motion is usually referred to as saltation, whereas, the sédiment transported
by suspension in the moving fluid is said to be suspended load sédiment
transport. In addition, when the fine particles are carried by moving fluid
in suspension, from the river estuaries are said to be wash load.
Chapter 3
Sédiment Transport
3.1 Introduction
In the Coastal and nearshore zones, where shore processes begin, there is
mixing, sorting and transportation of sédiments as well as run-off from the
land. Waves, winds and currents mould the shorelines of the world and
their interaction with the land and its run off détermines the configuration
of coastlines and the adjacent bathymetry. Man’s intervention into the natural processes taking place in the Coastal zone also has an impact on the
shoreline. These are in the form of discharges into the océan, thermal and
radioactive pollution, dredging, Coastal construction, mining and poaching.
There are many factors the affect the processes that take place in the
nearshore zone. The most importance are: degree of exposure to waves and
currents, supply of sédiments and run off to the coasts, topography of the
continental shelf and the adjacent coast and tidal range and the intensity
of the tidal current and Coastal climate.
Of ail these factors, waves play a prédominant rôle in the nearshore
processes.
3.2 Modes of Sédiment Transport
3.2.1 General
Sédiments are considered to be transported by one of the two major modes
i.e., either as bed load or suspended load. When the sédiments are transported along the seabed either by rolling, sliding or bounding it is said to
be bed load sédiment transport. When the transport rates are high, which
involving movement of bed materials in several layers with ail in contact
with one another are said to be a sheet flow. The transport by hopping
motion is usually referred to as saltation, whereas, the sédiment transported
by suspension in the moving fluid is said to be suspended load sédiment
transport. In addition, when the fine particles are carried by moving fluid
in suspension, from the river estuaries are said to be wash load.