Optimization of beach profile spacing: an applicable tool for coastal monitoring

Muñoz-Pérez

et al. 2020

JMSE

The southwestern coast of Spain is in a tidal zone (mesotidal) which causes the equilibrium profile to be developed in two different sections: the breakage section and the swash section. These two sections give rise to the typical bi-parabolic profile existing in tidal seas. The existence of areas with reefs/rocks which interrupt the normal development of the typical bi-parabolic profile causes different types of beach profiles. The objective of this article is designing an easy methodology for determining new formulations for the design parameters of the equilibrium profile of beaches with reefs in tidal seas. These formulations are applied on 16 profiles to quantify the error between the real profile data and the modelling results. A comparative analysis is extended to the formulations proposed by other authors, from which it is found that better results are obtained with the new formulations.

Section: Methodsmentioning

confidence: 99%

A Design Parameter for Reef Beach Profiles—A Methodology Applied to Cadiz, Spain

Muñoz-Pérez

et al. 2020

JMSE

“…Although increasing the number of profiles measured decreases the error associated with discretizing the domain, it also increases the survey budget. Therefore, in order to find a compromise between a 5% allowable error of estimation and the available monitoring budget, the methodology developed in [35] was used to determine a 50 m profile spacing at VB [39,40]. Optimizing profile spacing is important for cost savings, however, while techniques exist for sandy beaches, it is not clear how reef variability influences the spacing required to capture key changes with sufficient alongshore variability.…”

Section: Post-nourishment Monitoringmentioning

confidence: 99%

A Comparison of Beach Nourishment Methodology and Performance at Two Fringing Reef Beaches in Waikiki (Hawaii, USA) and Cadiz (SW Spain)

Muñoz-Pérez

Gallop

Moreno

2020

JMSE

Fringing reefs have significant impacts on beach dynamics, yet there is little research on how they should be considered in beach nourishment design, monitoring, and conservation works. Thus, the behavior and characteristics of nourishment projects at two reef protected beaches, Royal Hawaiian Beach (RHB) in Hawaii, USA, and Victoria Beach (VB) in Cadiz, Spain, are compared to provide transferable information for future nourishment projects and monitoring in fringing reef environments. The nourishment cost at RHB was nine times higher than VB. This is partly due to lower total volume and a more complex placement and spreading method at RHB, despite the much closer borrow site at RHB. There was a significant difference in post-nourishment monitoring frequency and assessment of accuracy. RHB elevation was monitored quarterly for 2.7 years at 30 m-spaced profiles, compared to 5 years of biannual surveys of 50 m-spacing at VB. An additional problem related to the presence of reefs at both RHB and VB was estimating the beach volume increase after nourishment, due to variable definitions of the 'beach' area and high alongshore variability in reef topography. At sites where non-native sediment is used, it is imperative to understand how wave and current energy changes due to reefs will influence nourishment longevity. Thus, differences in erosion and accretion mechanisms at both beaches have been detected, though are still little understood. Moreover, discrepancies in sediment porosity between the two sites (which should be surveyed in future nourishments) have been found, probably due to differences in the nourishment sand transportation and distribution methods. In summary, more dialogue is needed to explicitly consider the influence of fringing reefs on coastal processes and beach nourishment projects. time [2,3]. However, there is increasing research showing that the geologic setting plays a dominant role in contemporary beach morphodynamics [4][5][6][7]. In fact, some studies have taken into account the former geologic setting to design multifunctional artificial reefs that serve several purposes [8].One common type of geologically-controlled beach is situated landward of areas of hard bottom, such as rock or coral reefs. Reefs have large impacts on coastal hydrodynamics, sediment transport, and morphology, such as by influencing water level fluctuations [9], wave set-up and cross-reef currents [10], wave breaking, wave-induced flows, and wave attenuation over reef platforms [11][12][13][14][15], which affect the beach morphodynamics tidal range at multiple scales [16][17][18][19], even under hurricane conditions [20,21].Despite clear evidence that beaches with reefs behave differently to their non-reef counterparts, there has been scant attention given to how reefs should be considered in beach nourishment projects. A recent study by Habel et al. [22] focused on the methodology of a beach nourishment at Royal Hawaiian Beach (RHB), Waikiki, which is fronted by a fringing coral reef. They also analyzed the subseque...

“…A discrete number of transects was needed in order to analyse the shoreline changes and present the results. The separation between transects ranges from 300 m [29] in large beaches to 50 m for smaller ones [30]. The average value set by USACE [31] is 100 m and was thus used in this research, although with the GIS tool measurements can be obtained throughout the whole study area extension.…”

Section: Shoreline Evolution and Land-use Changementioning

confidence: 99%

Consequences of Anthropic Actions in Cullera Bay (Spain)

Pagán¹,

López²,

Bañón³

et al. 2020

JMSE

Urbanization and anthropogenic activities have generated significant imbalances in coastal areas. This study analysed the shoreline evolution of the Bay of Cullera (Spain), characterized by strong urban and tourist pressure and with important human interventions during the last century. The evolution of the shoreline was analysed using 60 years of aerial images since the 1950s of the seabed, the maritime climate and the distribution of sediment, as well as anthropogenic actions, such as urban development or the channelling of the Júcar River through the integration of information in a geographical information system (GIS). The results showed: (i) Changes in land-use, in which the substitution of the crop and mountain areas by urban areas was mainly observed. (ii) A general increase in the beach area, although there were important periods of erosion in some points due to anthropic actions. (iii) A significant decrease in the median sediment size in the whole bay since 1987, with a current D50 of 0.125–0.180 mm. The analysis carried out has made it possible to identify trends in coastal accumulation and regression in the different sections of the sector, as well as to demonstrate the usefulness and advantages of GIS.