llI. Sediment Transport
117
Van Rijn (1985) developed recently a formula for the computation of sediment
transport by waves and currents. The model is based upon a large number of
measurements of suspended sediment concentrations, both in the laboratory as
well as in the field. The consequent formulas for the computation of the resulting
suspended sediment transport have to be solved numerically, because of the
equations applied for the vertical diffusion of sediment.
Besides the suspended sediment transport a formulation is given for the
computation of the bed load transport. The formulas are given in section 2.1, this
chapter and chapter 1, this part.
Van Der Graaf and Van Overeem (1979) performed a comparative study between
the results of the Bijker formula, the adapted Engelund-Hansen formula and the
adapted Ackers-White formula*. Although the CERC-formula is not necessarily
correct in every respect ; this formula has been chosen as yardstick since it
predicts at least a mean value on the basis of quite a number of prototype
measurements. Although this method of comparison has some weakness, Van
Der Graaf and Van Overeem concluded that the Bijker formula is a better one
than either the adapted Ackers-White or the adapted Engelund-Hansen formula.
Furthermore the Bijker formula is, compared to the other formulas, rather
insensitive to effects of particle diameter, bottom slope and bed roughness. In
using this formula, a possible error in the estimation of the actual conditions
results in a slight error in the computed transport.
3
Cross-Shore Transport
3.1
Two-Line Theory of Bakker
Bakker (1968) has developed a two-line theory for the coastal morphology. The
coastal profile is schematized in two lines, denoted by the term "beach" and
"inshore", which changes as a result of gradients in the longshoreError!
Reference source not found, transport along both lines.
The interchange of sediment between both lines takes place in the form of
onshore-offshore transport. The magnitude of this onshore-offshore transport is
supposed to be proportional to the difference between the actual profile and the
equilibrium profile (see Fig. 20)
The adapted Engehmd-Hansen formula and the adapted Ackers-White are described in
section 2.1., ch. 1, this part.
117
Van Rijn (1985) developed recently a formula for the computation of sediment
transport by waves and currents. The model is based upon a large number of
measurements of suspended sediment concentrations, both in the laboratory as
well as in the field. The consequent formulas for the computation of the resulting
suspended sediment transport have to be solved numerically, because of the
equations applied for the vertical diffusion of sediment.
Besides the suspended sediment transport a formulation is given for the
computation of the bed load transport. The formulas are given in section 2.1, this
chapter and chapter 1, this part.
Van Der Graaf and Van Overeem (1979) performed a comparative study between
the results of the Bijker formula, the adapted Engelund-Hansen formula and the
adapted Ackers-White formula*. Although the CERC-formula is not necessarily
correct in every respect ; this formula has been chosen as yardstick since it
predicts at least a mean value on the basis of quite a number of prototype
measurements. Although this method of comparison has some weakness, Van
Der Graaf and Van Overeem concluded that the Bijker formula is a better one
than either the adapted Ackers-White or the adapted Engelund-Hansen formula.
Furthermore the Bijker formula is, compared to the other formulas, rather
insensitive to effects of particle diameter, bottom slope and bed roughness. In
using this formula, a possible error in the estimation of the actual conditions
results in a slight error in the computed transport.
3
Cross-Shore Transport
3.1
Two-Line Theory of Bakker
Bakker (1968) has developed a two-line theory for the coastal morphology. The
coastal profile is schematized in two lines, denoted by the term "beach" and
"inshore", which changes as a result of gradients in the longshoreError!
Reference source not found, transport along both lines.
The interchange of sediment between both lines takes place in the form of
onshore-offshore transport. The magnitude of this onshore-offshore transport is
supposed to be proportional to the difference between the actual profile and the
equilibrium profile (see Fig. 20)
The adapted Engehmd-Hansen formula and the adapted Ackers-White are described in
section 2.1., ch. 1, this part.