Coastal Engineering Journal

The present paper aims at getting the porous effect parameter G of a thin permeable wall. The reflection and transmission coefficients of a thin vertical porous wall with different porous shapes and porosities are obtained by a physical model experiment. The reflection coefficient and total horizontal wave load on a perforated caisson are also obtained by another experiment. Analytical solutions of wave interaction with these two vertical porous breakwaters are introduced. The reflection and transmission coefficients between predictions and experimental results of authors' and four other researchers' are compared. By comparisons, the estimate methods of the linearized resistance coefficient f and the inertial effect coefficient s of the permeable plate are recommended. Following the formula of Yu [1995], the values of G are calculated by f and s. A complete estimate method of porous effect parameter G is presented, which consists of the formula of Yu [1995] and the present experimental formula. The estimate method of G is validated by comparing the predicted values of the total horizontal wave loads on the perforated caisson with the experimental results.

In this paper, solitary wave run-down height and the geometric characteristics of solitary wave-induced strewing of armor units are investigated. In the experiments, natural sand and grain having different diameters are used. Run-down heights for not armored and armored beaches are evaluated and empirical formulas are suggested. From the results of these experiments, it was observed that armor units caused a decrease of approximately 35% run-down height. The relation between the run-up and run-down height is given by a formula. Subsequently, the area along the slope that had to be protected (such as a pipeline) was to be considered. In the experiments, this area was protected in two different ways (Alternative I, Alternative II). The strewing of the armor units forming the protective layer was studied. It is concluded that Alternative II is more suitable than Alternative I for protected area. The most important variables strewing of armor units were defined by using experimental results. These variables are written as a dimensionless group named as par 3 by using π theory. The empirical formulas between the geometric characteristics of strewing of armor units and dimensionless group are proposed through regression analysis.

Surge waves resulting from dam breaks have been responsible for numerous losses of life. A related situation is the tsunami surges advancing on dry coastal plains. Herein a simple dam break wave solution is presented. The results yield some simple expressions of the instantaneous free-surface profile and flow depths that compare well with well-known dam break wave data. The results are applied to tsunami surges on dry coastal plains and compared with some data set. The present development offers simple analytical expressions that compare well with both experimental data and more advanced theoretical solutions, and that are further well-suited for pedagogical purposes, computational model validation, and accurate real-time predictions of tsunami surges.

To increase physical insight into wave overwash processes at low-crested beach barriers, wave overtopping discharge events rather than the conventional average overtopping discharge need to be quantified. Also, in order to make intelligent use of the many empirical formulations on wave overtopping discharge at breakwaters from literature, a single-valued appropriate slope for a natural beach needs to be derived. To resolve these issues, laboratory experiments of composite-slope low-crested barriers were carried out. The tests deal with overwash on a smooth non-uniform slope on shallow foreshores.

The conventional average overtopping discharge concept does not represent the discontinuous character and associated strength of overtopping flow. Instead, e.g. for purposes of morphological modeling, wave overtopping should be treated as an event-based process. In this study, several new parameters such as the wave-averaged overtopping time, the relative total overtopping time, the overtopping asymmetry, the average maximum discharge and the average instantaneous discharge are defined and formulated.

A new approach for defining an equivalent slope is proposed in the parameterization of the overtopping discharge that also takes into account effects of the wave period. It is experimentally shown to be an improvement over the conventional approach by Van der Meer [1998], especially eligible for low-crested sandy slopes such as barriers, dikes, dunes, etc on shallow foreshores.

This study was undertaken to find out the suitable breaking wave formulas for computing breaker depth, and corresponding orbital to phase velocity ratio and breaker height converted with linear wave theory. A large amount and wide range of published laboratory data (695 cases collected from 26 sources of published laboratory data) were used to examine and develop the breaker formulas. Examination of some existing formulas indicates that none of them can be used for a wide range of experimental conditions. New breaker formulas were developed based on the re-analysis of the existing formulas. Overall, the new formulas give good predictions over a wide range of experimental conditions.