New methodology for describing the equilibrium beach profile applied to the Valencia's beaches (original) (raw)

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

Journal of Marine Science and Engineering, 2020

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.

Evolutive trends of nourished beaches in SW Spain

Journal of Coastal Research

The main purpose of this paper is to analyse the behaviour of nourished beaches in Cadiz Bay (SW Spain). Similar nourishment modalities were used in all studied beaches: sand was dredged from the sea floor and split on the beach to create a raised, flat berm. These nourishment modalities transformed the initially dissipative profiles into intermediate-reflective ones. The monitoring program showed an asymptotic stationary beach trend, tending to achieve a "minimum equilibrium volume". In fact, despite the initial, important erosion, beaches acquired a seasonal behaviour with dissipative state associated to erosive conditions and an intermediate one during constructive conditions, general beach stability. Finally, it was observed that a nourishment work carried out during fair weather conditions greatly favours beach stability because sand is relocated and distributed in a natural way under low energy conditions. : ADDITIONAL INDEX WORDS Coastal erosion, volumetric variations, nourishment works, Bay of Cádiz.

Morphodynamic study of the Ondarreta Beach in San Sebastian (Spain)

Environmental Problems in Coastal Regions VI, 2006

Ondarreta Beach is one of the most emblematic and visited beaches in the Basque Country. This beach is part of La Concha bay, with Santa Clara Island in the middle of the bay and a semi submerged dike and reef in front of it. The combination of this morphology together with the tidal range in the area (max. springs 4.6m) results in a very particular wave climate. The beach contains different strata of sand, natural rocks and the remains of artificial structures. Therefore, rocks sometimes appear at the surface, depending on the changes of the beach profile. This situation harms the normal use of the beach and can be a risk for the users. During recent years this process has increased and, especially in the summer, a big part of the intertidal profile of the West part of the beach shows a gravely and rocky profile. In 2003, the town council of San Sebastian entrusted AZTI Foundation with the study of this beach. For this purpose AZTI planned the data analysis and the morphodynamic study of the evolution of the beach in three different time scales, in order to clarify whether the recent problems at the beach are an increasing erosive process, or part of a natural cycle. The three different time scales of analysis of morphodynamic processes taking place in this beach are:-Short term scale: wave data measurement and analysis, modeling of wave, current and sediment transport.-Medium term scale: analysis of seasonal equilibrium shape and profile.-Long term scale: analysis of morphodynamic evolution of the whole system (the bay). This analysis has contributed to the management of the beach, implying artificial seasonal sand movements, trying to encompass the natural processes and shoreline protection with the recreational use of the beach.

Morphodynamic responses of nourished beaches in SW Spain

Journal of Coastal Conservation

Coastal erosion in SW Spain is affecting man-made structures and beaches that represent an important economic resource in the area. In the last decade the Spanish government carricd out several nourishment works that have limited durahility. i\:!ost of the artificial beach fills consist of a spill of natural dredged sand on the visihle beach. leading to a tlat. anificial herm with an important seaward slope and a narrow foreshore. As a result, the initial dissipative profile was transformed into a fully reflective one. A beach monitoring program was carried out to record morphological evolution after the nourishment \I/orks. Several field assessments of disturbance depth were a!so made to characterize beach morphodynamics of a nourished beach (Rota) and a natural dissi pati ve one (Tres Piedras). whose slope \vas similar to the pre-nourishment gradient of Rota beach. Natural dissipative beaches were characterized by spilling breakers that did not signifi-C:l!1tlyaffect bottom sand. The severe erosion recorded in the nourished zones \I,:as related to the new morphodynamic rcgime acting on these beaches. which was controlled by high erosive plunging breakers associated with high foreshore slopes. In conclusion. other nourishment practices should be used. better adapted to the natural beach morphodynamics of thc zone. taking also into account the original grain size and density of the beach sands, in order to obtain more durable artificial beaches.

The Equilibrium Concept, or…(Mis)concept in Beaches

2021

Beaches, as deposits of unconsolidated material at the land/water interface, are open systems where input and output items constitute the sediment budget. Beach evolution depends on the difference between the input/output to the system; if positive the beach advances, if negative the beach retreats. Is it possible that this difference is zero and the beach is stable? The various processes responsible for sediment input and output in any beach system are here considered by taking examples from the literature. Results show that this can involve movement of a volume of sediments ranging from few, to over a million cubic meters per year, with figures continuously changing so that the statistical possibility for the budget being equal can be considered zero. This can be attributed to the fact that very few processes are feedback-regulated, which is the only possibility for a natural system to be in equilibrium. Usage of the term “beach equilibrium” must be reconsidered and used with grea...

Validity of the equilibrium beach profiles: Nile Delta Coastal Zone, Egypt

Geomorphology, 2009

Beach profile equilibrium is the principal concept assumed by most numerical modelling. The response of beach profile configuration to natural and anthropogenic changes could be predicted to help in selecting the most appropriate engineering design required to mitigate coastal erosion and accretion alongshore. Thus, in order to apply coastal engineering projects, the predicted profile of equilibrium should be close enough to the measured profile. Therefore, before application of numerical modelling techniques, equilibrium expressions have to be validated at the study site. This research aims to assess the validity of the equilibrium profile concept on the Nile Delta coast based on beach profiles surveyed in 1990 from the main promontories; Abu-Quir Bay, the Rosetta promontory and the El-Burullus promontory. The results indicate that the equilibrium beach profile is consistent with the measured profiles at the study sites beyond 200 m distance offshore at − 4 m depth. In contrast, the equilibrium status is not valid along the beach face at − 1 m depth. Accreted beaches at Abu-Quir bay and Burullus promontory are characterized by wide berms and gentle beach face whereas eroded stretches at Rosetta promontory have a narrow berm and steep beach faces. The measured profiles are also compared with the exponential beach profile concept. An exponential hypothesis is not valid along the Nile Delta coast. Profiles measured at Abu-Quir, Rosetta and El-Burullus depart significantly from the exponential equation. Despite the fact that equilibrium expression can describe beach profiles along the Nile Delta, one equilibrium profile equation is not sufficient to assess all beach profiles. This can be explained as the morphology of beach profiles is subjected to some factors including; sediment characteristics, wave parameters and closure depth, which vary alongshore. Analysis of the validity of the equilibrium beach profile is recommended to get accurate results in modelling simulations and design the most appropriate engineering projects required for shore protection.

Behavior of the Beaches on the North of Spain

Coastal Engineering Proceedings, 2012

This study is an analysis about morphological problems, due to anthropic or other causes. We carried out the behavior and evolution of ten beaches on the North Coast of Spain, in order to see if climate change was involved. To do this, it was necessary to consider data from Cantabrian sea buoys during fifteen years. Besides we made use of, maps, nautical charts and bathymetric records. We applied a kind of parameters to measure the energy including on each beach, so to be able to compare therm.

Equilibrium Configuration of Sandy Embayed Beaches from the Southwest Portuguese Rocky Coast

Journal of Coastal Research

The planform of five embayed sandy beaches (São Torpes, Furnas, Amoreira, Monte Clérigo and Arrifana), from the Southwest Portuguese rocky coast were compared to theoretical equilibrium curves (logarithmic spiral and parabolic). The beach planform configurations were defined based on aerial photography and the 2 m (MSL) contour extracted from DGPS field surveys (Furnas and Amoreira beaches). In order to analyse beaches morphodynamic, the volumetric active sediment changes, wave climate characteristics and wave propagation effects to nearshore were characterized. The wave breaking height and beach configuration is responsible for different degrees of exposure to the dominant NW wave direction. Major volumetric changes were largely associated with storm incidence. Comparison between real beach planform and predicted static equilibrium configurations suggests that the Arrifana beach represents a perfect example of a fully developed parabolic bay shape while, the other four beaches are not represented by any theoretical curve approach. In fact, the 2 m (MSL) contour at the Amoreira beach describes a convex beach planform tendency. The effect of the wave direction over the diffraction point was tested but the results points to a low diffraction effect. The Furnas beach revealed a high width variation at the northern extreme related with a more energetic wave climate, dominant from West, with lower diffraction. This study shows that the studied beaches presents a complex dynamic equilibrium that is a function of the subaerial beach configuration, the intertidal bar system variation, the degree of exposure to the dominant NW wave direction and the storm incidence.

Morphodynamic characterization of Cádiz beaches (SW Spain)

Journal of Coastal Research

Data obtained from a topographic and a sedimentological beach monitoring program, combined with analysis of wave characteristics, allowed the morphodynamic characterization and classification of the littoral zone between Chipiona and Valdelagrana (Cadiz, SW Spain). Wave characteristics and grain size were used to apply the MASSELINK and SHORT (1993) classification of morphodynamic beach states. Most of the studied beaches belonged to the "dissipative" and/or "intermediate" beach states and there was good agreement between observed beach profiles and predicted states. Discrepancies were observed in the Chipiona-Rota sector due to the effects of a rock shore platform that affected beach morphology and grain size variability.

On the profile evolution of three artificial pebble beaches at Marina di Pisa, Italy

Geomorphology, 2011

in order to define the response of the beaches to major storms that occurred during the study. Two beaches are similar, the third differs in length and in the level of protection, being less than half the length of the others and devoid of an offshore submerged breakwater. The work was achieved by means of accurate topographic surveys intended to reconstruct the beach profile from the backshore up to the foreshore-upper shoreface transition (step). The surveys were performed with an RTK-GPS instrument, which provided extremely precise recording of the beach. The most significant features of the beaches were tracked during each survey; in particular, the landward foot of the storm berm, the crest of the storm berm, the coastline, and the step crest were monitored. Five cross-shore transects were traced on each beach. Along these transects, any meaningful slope change was recorded to obtain accurate sections of the beach. The field datasets were processed with AutoCAD software to compare the beach profile evolution during the year-long research. The results showed a comparable evolution of the twin beaches: the resulting storm berm retreat of about 15 to 19 m is a remarkable feature considering the coarse grain size and the offshore protection. Due to the absence of the breakwater, the third beach was characterized by even higher values of recession (over 20 m), and showed hints of wave reflection-related processes after the huge, steep storm berm had been formed and grown after the high energy events. These processes were not as evident on the twin beaches. These results underline the different response of three similar protection schemes, and the importance that frequent monitoring of the beach morphology holds when it comes to coastal management issues.