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Coastal Engineering: Theory and Practice
3.2.3 Load transport general approach
Generally sédiment transport takes place either as bed load or the combination of both bed load and suspended load. The transport by suspended load
alone is rare and occurs only in the case of fine silts. The combined load
transport in general is referred to as total load. In practice, bed loads and
suspended loads will be calculated separately and the résultant sum will be
the total load. Practically, the séparation of bed and suspended load are
very difficult, researchers hâve tackled the total load problem by matching
the transport équations at well-defined height.
3.3 Littoral Transport
3.3.1 General
Littoral transport is defined as the movement of sédiment particles within
the surf zone, that is, the zone close to the shoreline. If the flow involves
sédiments, it is no longer said to be a simple fluid flow as it involves two
components. Sédiment transport can be influenced by either waves or currents or a combination of both. The theory of momentum flux is used to
explicate the phenomenon of wave set-up and longshore current génération. It is explained as the excess flow of momentum due to the presence of
waves (with units of force/unit length). It arises from the orbital motion of
individual water particles in the waves. The knowledge of littoral transport
gives a clear understanding of momentum flux theory. Sédiment transport
is defined as the product of instantaneous concentration and instantaneous
vélo city as given,
1 ('d+r) rt’
S=—
/ c(z, t)u(z,
£ Jo Jo
(3.1)
where, S — sédiment transport rate expressed in [m3/m2], t' — intégration
time, d — water depth, g — instantaneous water surface élévation, c(z, t) —
instantaneous concentration of material, u(z,t) — instantaneous velocity
component, z — élévation above the sea bed and t — time.
Sédiment transport is classified as cross-shore transport and as alongshore transport based on the direction of net drift. If the average net drift
of sédiments is perpendicular to the shoreline, it is referred to as cross-shore
transport, whereas, if the net drift of sédiments is parallel to the shoreline,
it is said to be alongshore sédiment transport. The instantaneous motion
of sédimentary particles has both a cross-shore and alongshore component.
Both alongshore and cross-shore transport are significant in the surf zone.
Coastal Engineering: Theory and Practice
3.2.3 Load transport general approach
Generally sédiment transport takes place either as bed load or the combination of both bed load and suspended load. The transport by suspended load
alone is rare and occurs only in the case of fine silts. The combined load
transport in general is referred to as total load. In practice, bed loads and
suspended loads will be calculated separately and the résultant sum will be
the total load. Practically, the séparation of bed and suspended load are
very difficult, researchers hâve tackled the total load problem by matching
the transport équations at well-defined height.
3.3 Littoral Transport
3.3.1 General
Littoral transport is defined as the movement of sédiment particles within
the surf zone, that is, the zone close to the shoreline. If the flow involves
sédiments, it is no longer said to be a simple fluid flow as it involves two
components. Sédiment transport can be influenced by either waves or currents or a combination of both. The theory of momentum flux is used to
explicate the phenomenon of wave set-up and longshore current génération. It is explained as the excess flow of momentum due to the presence of
waves (with units of force/unit length). It arises from the orbital motion of
individual water particles in the waves. The knowledge of littoral transport
gives a clear understanding of momentum flux theory. Sédiment transport
is defined as the product of instantaneous concentration and instantaneous
vélo city as given,
1 ('d+r) rt’
S=—
/ c(z, t)u(z,
£ Jo Jo
(3.1)
where, S — sédiment transport rate expressed in [m3/m2], t' — intégration
time, d — water depth, g — instantaneous water surface élévation, c(z, t) —
instantaneous concentration of material, u(z,t) — instantaneous velocity
component, z — élévation above the sea bed and t — time.
Sédiment transport is classified as cross-shore transport and as alongshore transport based on the direction of net drift. If the average net drift
of sédiments is perpendicular to the shoreline, it is referred to as cross-shore
transport, whereas, if the net drift of sédiments is parallel to the shoreline,
it is said to be alongshore sédiment transport. The instantaneous motion
of sédimentary particles has both a cross-shore and alongshore component.
Both alongshore and cross-shore transport are significant in the surf zone.