Predicting Crenulate Bay Profiles from Wave Fronts: Numerical Experiments and Empirical Formulae

Abstract

For crenulate-shaped bays, the coastal outline assumes a specific shape related to the predominant waves in the area: it generally consists of a tangential zone downcoast and a curved portion upcoast. Many coastal engineers have attempted to derive an expression of the headland bay shapes that emerge when a full equilibrium is reached (stable or dynamic). However, even though models for static equilibrium bays exist, they are merely of an empirical kind, lacking further insight on relationships between incident wave characteristics and beach shape. In addition, it is commonly believed that shoreline profiles tend to follow wave fronts, but this has been never fully verified. In this paper, we investigate a possible correlation between static equilibrium profiles and wave front shapes. Numerical experiments have been performed using the MIKE 21 Boussinesq Wave module, and the generated wave fronts have been compared to the hyperbolic-tangent equilibrium profile. A thoughtful analysis of results revealed that a single-headland equilibrium profile is merely the wave front translated perpendicularly to the wave direction at the headland tip, without any influence of wave period or in wave direction. A new function called the “wave-front-bay-shape equation” has been obtained, and the application and validation of this formula to the case-study bay of the Bagnoli coast (south-west of Italy) is described in the paper.

On the Indirect Estimation of Wind Wave Heights over the Southern Coasts of Caspian Sea: A Comparative Analysis

“…A substantial improvement in the predictive performance of the indirect sea wave estimations obtained in the present study case can be reached by combining them with the most advanced methods for the quantitative assessment of stochastic uncertainty propagation [65][66][67][68][69][70][71][72], as reported by previous environmental and ecohydraulic engineering studies [73][74][75][76][77][78][79][80]. Finally, as illustrated in Figure 6, in this study, a good correlation was observed between average buoy-based and average satellite-based wave heights (m) over the southern coasts of the Caspian Sea, associated with a slight overestimation in all the examined months.…”

“…A substantial improvement in the predictive performance of the indirect sea wave estimations obtained in the present study case can be reached by combining them with the most advanced methods for the quantitative assessment of stochastic uncertainty propagation [65][66][67][68][69][70][71][72], as reported by previous environmental and ecohydraulic engineering studies [73][74][75][76][77][78][79][80].…”

Embayed Beach Configuration Explained by Wave Sheltering

“…Hybrid approaches, also called one-line shoreline models in ref. 5 , couple oceanographic forcing with the morphological response of the beach 5,[19][20][21][22][23] . While these approaches vary in their level of simpli cation and the physical processes they describe, they generally: i) resolve the propagation of deep-water waves to the shore; ii) use the nearshore wave regime to estimate potential sediment transport rates; and iii) compute shoreline planform using transport rates and the continuity equation.…”

Trigno River Mouth Evolution via Littoral Drift Rose

“…Most notably, the equivalent direction parameter (equal to the LDR null point) is of significant importance in shoreline evolution forecast, as it is nothing but the dominant direction of wave climate that persistently affects and sculpts the shoreline over years. In practical coastal engineering, the total wave climate is in fact seldom reduced to the equivalent wave component in midlong-term analysis of shoreline evolution, a procedure that has been widely applied in the literature, particularly in the field of static equilibrium crenulated bays [17]. One of the major findings concerning the LDR concept [3] is that, in terms of littoral drift, the effects of a deep-water wave climate can be equated to a single equivalent wave component, with parameters H s0,eq , T p0,eq , and α 0,eq , i.e.,…”