Author(s): Miguel Santamaria Cervantes; Pilar Diaz-Carrasco; Maria Victoria Moragues; Maria Clavero; Miguel Angel Losada

Linked Author(s): Miguel Santamaría Cervantes

Keywords: Breakwater; Run-up; Flow regimes; Coastal protection; Engineering formulas

Abstract: Global warming is producing a progressive sea level rise. This situation results in greater and more frequent extreme events whose effects have strong impacts not only in coastal low-lying areas, but also in coastal structures. In general, rubble mound breakwaters are the main maritime structures used to protect ports and coastal zones. The maximum run-up (Ru), and the corresponding run-down (Rd), measured vertically from mean sea level at rest, define the maximum and minimum height that the wave reaches above and below mean sea level in each wave cycle. If the run-up height is higher than the freeboard of the structure, it will produce overtopping (Q). Both are relevant factors in the design of breakwaters in coastal areas due to the damage to people, properties, infrastructures, etc. and the associated costs that such repairs may incur. Nowadays, most of the formulae used to design protective structures have been obtained experimentally in a wave flume. Some of them for run-up are Van Der Meer & Stam, 1992; Ahrens et al., 1993; Van Gent, 2001; Hughes, 2004; Kobayashi et al., 2008, among others. All of them using the Iribarren number (Ir) as principal similarity parameter between model and prototype. However, Díaz-Carrasco et al. (2020) showed that there is not a biunivocal relationship between Ir and the breaker type. Recently, Moragues et al., 2020 and Moragues & Losada, 2021 showed that wave breaker types on a given plane impermeable slope depend primarily on the wave steepness and relative water depth at the toe of the slope. The product (\chi=h/L·HI/L) and the quotient (\gamma=H_I/h) of these wave parameters determine the observed flow regimes on the slope, namely wave breaker types, run-up and run-down. In the conference the results of diverse group of tests that were carried out at the IISTA-UGR wave laboratory will be presented. Several different slope angles were tested. Run-up and run-down were measured with cameras located oblique to the ramp and the breaker types were identified through photographs. Three flow regimes can be observed: fully reflective (surging), fully dissipative (weak plunging and spilling) and transitional (strong plunging, strong and weak bore). It will be shown that the experimental results in the transitional regimes are severely scattered due to different processes related with the dual dissipative-reflective partition of the incident wave energy. Based on these results in the final paper will be discussed the uncertainty of the run-up/run-down formulas based on lab-experiments and their performance for real-world design conditions.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022900

Year: 2022