Optimized Reliability Based Upgrading of Rubble Mound Breakwaters in a Changing Climate

Abstract

The present work aims at presenting an approach on implementing appropriate mitigation measures for the upgrade of rubble mound breakwaters protecting harbors and/or marinas against increasing future marine hazards and related escalating exposure to downtime risks. This approach is based on the reliability analysis of the studied structure coupled with economic optimization techniques. It includes the construction of probability distribution functions for all the stochastic variables of the marine climate (waves, storm surges, and sea level rise) for present and future conditions, the suggestion of different mitigation options for upgrading, the construction of a fault tree providing a logical succession of all events that lead to port downtime for each alternative mitigation option, and conclusively, the testing of a large number of possible alternative geometries for each option. A single solution is selected from the total sample of acceptable geometries for each upgrading concept that satisfy a probabilistic constraint in order to minimize the total costs of protection. The upgrading options considered in the present work include the construction or enhancement of a crown wall on the breakwater crest, the addition of the third layer of rocks above the primary armor layer of the breakwater (combined with crest elements), the attachment of a berm on the primary armor layer, and the construction of a detached low-crested structure in front of the breakwater. The proposed methodology is applied to an indicative rubble mound breakwater with an existing superstructure. The construction of a berm on the existing primary armor layer of the studied breakwater (port of Deauville, France), seems to be advantageous in terms of optimized total costs compared to other mitigation options.

Probabilistic Comparison of Static and Dynamic Failure Criteria of Scour Protections

“…Nevertheless, they can be seen as a starting point for the discussion on what it could be acceptable safety level of similar marine rubble-mound structures. The results shown for both static and dynamic criteria do not fall far from the probabilities of failure often discussed in other similar structures, for example, in References [47,48].…”

Nonstationary Extreme Value Analysis of Nearshore Sea-State Parameters under the Effects of Climate Change: Application to the Greek Coastal Zone and Port Structures

“…Reliability analysis, corresponding to assessing failure probabilities of such engineered defenses, forms an inherent part of a risk-based approach to designing new or evaluating the performance of existing coastal structures. Castillo et al [36], Dai Viet et al [37], Van Gelder et al [38], Buijs et al [39], Kim & Suh [40], Galiatsatou and Prinos [41], Naulin et al [42], Nepal et al [43] and Galiatsatou et al [44] performed reliability analysis of coastal and harbor structures to determine failure probabilities including different failure mechanisms of the defenses, and further proposed modern (both probabilistic and stochastic) methods and techniques to be included either in the engineering design phase or the construction upgrading process.…”

“…Area 1 is located in the northern Aegean basin at the coastal zone of the Thracian Sea pertaining the city of Alexandroupoli; Area 2 is situated in the east-central part of the Aegean and represents the southern coasts of Lesvos Island (containing the town of Eresos); and Area 3 refers to the west-central northern coasts of Crete, around the city of Iraklion, in the southern Aegean Sea. The choice of case studies was based on former EVA modeling dataset selection by Hosking and Wallis type measures of statistical homogeneity for high quantiles [15,26,44].…”

Climate Change, Coasts and Coastal Risk

“…Economic optimization methods can be used for establishing economically optimal failure probabilities, to support risk-informed decision making. Along these lines, Galiatsatou et al [12] present the economic optimization of measures to improve the reliability of a rubble mound breakwaters. In the Final paper of this issue, Dastgheib et al [13] examine potential shoreline changes for sites in Sri Lanka using a probabilistic coastline recession model, and balance risk and reward to determine economically optimal setback lines.…”