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Open AccessFeature PaperArticle

Calculated Potential Bedload Versus Real Transported Sands along the Guadiana River Estuary (Spain–Portugal)

by

Juan A. Morales

,

Claudio Lozano

and

Mouncef Sedrati

J. Mar. Sci. Eng. 2019, 7(11), 393; https://doi.org/10.3390/jmse7110393 - 05 Nov 2019

Cited by 2 | Viewed by 1679

Abstract

The Guadiana estuary is a coastal system located in the southwest of the Iberian Peninsula and is the natural border between Portugal and Spain. It is a rock-bounded estuary which extends along more than 40 km and is characterized by a semidiurnal mesotidal [...] Read more.

The Guadiana estuary is a coastal system located in the southwest of the Iberian Peninsula and is the natural border between Portugal and Spain. It is a rock-bounded estuary which extends along more than 40 km and is characterized by a semidiurnal mesotidal regime. This paper represents an approach to the bedload transport across two flow sections located in the fluvial and marine domains. In the fluvial profile, the most frequent bedform is the plane bed. In the marine area the bed of the deep channel is composed of well-sorted sand, while a lateral bar displays partially cohesive sediments with dominant fine sands in a matrix of clayey silts. Data were acquired during spring and neap tides. Near-bottom water velocities were registered by an acoustic Doppler current profiler (ADCP). Density and bed rugosity were determined in sediment samples. These data were employed using Bagnold’s equation (1963) to quantify the potential bedload (Qb). Further, real bedload values (Sb) were obtained by using Poliakoff traps. The comparison of the results of Qb under both ebb and flood conditions demonstrated a clear river-to-sea net transport in both sectors. The values of Sb were lower than those of Qb in every condition. The sand input across the fluvial estuary cannot supply the potential bedload in the lower domain of the channel, thereby causing a deficit that explains this lack of agreement between potential and real transport. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessFeature PaperArticle

Coastal Retreat and Sedimentation during the Last 3000 Years. Atlantic Coast of NW Spain

by

Ramón Blanco-Chao

,

Manuela Costa-Casais

,

Daniel Cajade-Pascual

and

Gonzalo Gómez-Rey

J. Mar. Sci. Eng. 2019, 7(10), 331; https://doi.org/10.3390/jmse7100331 - 24 Sep 2019

Cited by 5 | Viewed by 2239

Abstract

During the last glaciation, thick nival and periglacial sediments buried large sectors of the NW coast of Spain. The sediments were mostly eroded by the rising sea level during the Holocene, but in several places they remain, forming sedimentary cliffs. Radiocarbon dates obtained [...] Read more.

During the last glaciation, thick nival and periglacial sediments buried large sectors of the NW coast of Spain. The sediments were mostly eroded by the rising sea level during the Holocene, but in several places they remain, forming sedimentary cliffs. Radiocarbon dates obtained at the topmost layers of these cliffs prove that continental sedimentation was active until very recent times, followed by a retreat of the cliffs. During the first stages of the transgression, the erosion of the cliffs and the changes in the coastal system were controlled by the rising sea-level. Once the sea-level stabilized, the exhumation of inherited landforms, the supply of sediments, and a continuous continental sedimentation became the main factors. The last stages of cliff retreat were almost synchronous with the sedimentation of the upper layers of the deposits. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessArticle

Tsunami Boulders on the Rocky Coasts of Ibiza and Formentera (Balearic Islands)

by

Francesc Xavier Roig-Munar

,

Antonio Rodríguez-Perea

,

José Angel Martín-Prieto

,

Bernadi Gelabert

and

Joan Manuel Vilaplana

J. Mar. Sci. Eng. 2019, 7(10), 327; https://doi.org/10.3390/jmse7100327 - 20 Sep 2019

Cited by 9 | Viewed by 3252

Abstract

Large boulders have been found in marine cliffs from 7 study sites on Ibiza and Formentera Islands (Balearic Islands, Western Mediterranean). These large boulders of up to 43 t are located on platforms that form the rocky coastline of Ibiza and Formentera, several [...] Read more.

Large boulders have been found in marine cliffs from 7 study sites on Ibiza and Formentera Islands (Balearic Islands, Western Mediterranean). These large boulders of up to 43 t are located on platforms that form the rocky coastline of Ibiza and Formentera, several tens of meters from the edge of the cliff, up to 11 m above sea level and several kilometers away from any inland escarpment. Despite than storm wave height and energy are higher from the northern direction, the largest boulders are located in the southern part of the islands. The boulders are located in the places where numerical models of tsunami simulation from submarine earthquakes on the North African coast predict tsunami impact on these two islands. According to radiocarbon data and rate of growth of dissolution pans, the ages of the boulders range between 1750 AD and 1870 AD. Documentary sources also confirm a huge tsunami affecting the SE coast of Majorca (the largest Balearic Island) in 1756. The distribution of the boulders sites along the islands, the direction of imbrication and the run-up necessary for their placement suggest that they were transported from northern African tsunami waves that hit the coastline of Ibiza and Formentera Islands. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessFeature PaperArticle

Testing A Methodology to Assess Fluctuations of Coastal Rocks Surface Temperature

by

Marta Pappalardo

and

Martina D’Olivo

J. Mar. Sci. Eng. 2019, 7(9), 315; https://doi.org/10.3390/jmse7090315 - 12 Sep 2019

Cited by 3 | Viewed by 1674

Abstract

The aim of this work is testing a cheap and user-friendly methodology suitable for studying temperature fluctuations of coastal rocks’ surfaces. An infrared thermometer was used, that permits a contactless measurement of the average surface temperature of a patch around a measuring point. [...] Read more.

The aim of this work is testing a cheap and user-friendly methodology suitable for studying temperature fluctuations of coastal rocks’ surfaces. An infrared thermometer was used, that permits a contactless measurement of the average surface temperature of a patch around a measuring point. Temperature was measured in an array of selected plots every 45 min from dawn to sunset in a 20 m² study area along the rocky coast of Calafuria (NW Italy). During the experiment daily temperature in all plots was minimum at dawn and quickly reached its peak value shortly after sun culmination; subsequently, it underwent a small-gradient decrease until sunset. In connection with temporary sun-shading and wind gusts relevant short-term rock surface temperature fluctuations were recorded. Considering mean daily temperature in each plot, it proved to be positively correlated with distance from the shoreline. As regards daily temperature range, its amplitude progressively increased moving farther from the shoreline. The measuring points located where the rock is extensively covered by barnacles experience a temperature magnification effect, possibly due to a micro-greenhouse effect triggered by the production of carbon dioxide by this biota. The entity of measured daily temperature fluctuations is ca. one order of magnitude greater than air temperature fluctuations measured at the same elevation in the closest meteorological station. The results of this work highlight that the infrared thermometer is an effective tool to measure rock surface temperature along rocky coasts, capable of detecting temperature fluctuations more effectively than traditionally employed data loggers. Moreover, this work emphasizes the relevance of temporary sun-shading and wind gusts in triggering short-term rock surface temperature fluctuations, potentially capable of enhancing thermal fatigue and foster surface rock breakdown. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessArticle

Community Perceptions of Tourism Impacts on Coastal Protected Areas

by

Nuria Navarro

J. Mar. Sci. Eng. 2019, 7(8), 274; https://doi.org/10.3390/jmse7080274 - 14 Aug 2019

Cited by 10 | Viewed by 3527

Abstract

The Dominican Republic is one of the countries with the highest growing number of tourists in coastal protected areas. The objective of this study was to examine the perceived impact of tourism on three coastal national parks, involving all the sectors related to [...] Read more.

The Dominican Republic is one of the countries with the highest growing number of tourists in coastal protected areas. The objective of this study was to examine the perceived impact of tourism on three coastal national parks, involving all the sectors related to these protected areas and tourism. Workshops were carried out in the coastal protected areas studied. The results revealed the poor integration of local communities in the management plans, the lack of information on protected areas, and the poverty of the majority of the resident families despite income of tourism. The findings of this study highlighted the concept of a carrying capacity or threshold for tourism development. Lower to moderate levels of tourism development appeared beneficial, but as tourism development increased, perceptions of the community worsened. The results also confirmed that tourism contributes to environmental degradation, mainly due to contamination of rivers and coastlines, accumulation of waste, and over-exploitation of natural resources. A series of strategies is proposed to minimize this impact. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessArticle

Trends in the Recent Evolution of Coastal Lagoons and Lakes in Galicia (NW Iberian Peninsula)

by

Pedro Fraga-Santiago

,

Alejandro Gómez-Pazo

,

Augusto Pérez-Alberti

,

Pablo Montero

and

Xose Lois Otero Pérez

J. Mar. Sci. Eng. 2019, 7(8), 272; https://doi.org/10.3390/jmse7080272 - 14 Aug 2019

Cited by 5 | Viewed by 2670

Abstract

Coastal lagoons are habitats of great environmental value. However, they are currently subject to major threats, particularly due to increasing sea levels. This study aims to identify changes—both natural and induced by anthropic activity—and their impact on the recent evolution of three different [...] Read more.

Coastal lagoons are habitats of great environmental value. However, they are currently subject to major threats, particularly due to increasing sea levels. This study aims to identify changes—both natural and induced by anthropic activity—and their impact on the recent evolution of three different types of coastal lagoons in Galicia (Louro, Vixán, and Xuño). The application of information obtained through laser imaging detection and ranging (LiDAR) techniques suggests that the outer limits of the three lagoon systems have not experienced any relevant changes in the last 60 years (i.e., no occupation of the lagoon area has been identified). However, the internal configuration of these wetland areas has experienced some alterations. A generalized increase in the area occupied by macrophytic communities (Phragmites australis, Scirpus maritimus, Juncus maritimus, etc.) has been observed. Image interpretation by geographic information systems (GIS) and field surveys suggest that the area currently occupied by macrophytes experienced a 7% to 63% increase at the expense of the free water body. This loss of flooded area is consistent with the increase in sedimentation rates associated with the convergence of several causes, such as the abandonment of traditional macrophyte biomass harvesting and agricultural activities around the lagoons, the expansion of riparian forests, and sediment contributions by erosion due to recurrent forest fires within the drainage basins of each lagoon. Finally, water and sediment composition suggest that, of the three studied lagoons, two of them (Louro and Vixán) are included within the definition of “coastal lagoons” (habitat code 1150) by the Habitats Directive (Directive 92/43/EEC), while the Xuño lagoon should be considered a “natural eutrophic lake” (habitat code 3150). Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessArticle

Geomorphological Processes and Environmental Interpretation at Espalmador islet (Western Mediterranean)

by

Laura del Valle Villalonga

,

Alida Timar-Gabor

and

Joan J. Fornós

J. Mar. Sci. Eng. 2019, 7(5), 144; https://doi.org/10.3390/jmse7050144 - 14 May 2019

Cited by 3 | Viewed by 2464

Abstract

This study presents a sedimentological and stratigraphical description of the Pleistocene deposits cropping out in Espalmador islet (Illes Pitiüses). Four major sedimentary facies including the succession of aeolian, marine, colluvial and edaphic environments are described. The sedimentological and stratigraphical analysis of these deposits [...] Read more.

This study presents a sedimentological and stratigraphical description of the Pleistocene deposits cropping out in Espalmador islet (Illes Pitiüses). Four major sedimentary facies including the succession of aeolian, marine, colluvial and edaphic environments are described. The sedimentological and stratigraphical analysis of these deposits allows the reconstruction of the coastal Pleistocene environmental and geomorphological history of the Espalmador islet. The coastal relief and the fluctuations of the sea level mainly control the Pleistocene coastal landscape evolution on Espalmador. Episodes of aeolian activity and dune formation related to a predominant northwestern wind direction can be linked to periods of low sea level where a high amount of marine sediment is exposed on the shelf platform. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Open AccessArticle

Recent Evolution (1956–2017) of Rodas Beach on the Cíes Islands, Galicia, NW Spain

by

Alejandro Gómez-Pazo

,

Augusto Pérez-Alberti

and

Xose Lois Otero Pérez

J. Mar. Sci. Eng. 2019, 7(5), 125; https://doi.org/10.3390/jmse7050125 - 30 Apr 2019

Cited by 15 | Viewed by 2930

Abstract

Sedimentary coastal areas change rapidly and are economically and environmentally important. This research focuses on determining the extent to which natural dynamics and human activity have contributed to visible changes on Rodas, Cíes Islands in southwestern Galicia (NW Spain). The number of visitors [...] Read more.

Sedimentary coastal areas change rapidly and are economically and environmentally important. This research focuses on determining the extent to which natural dynamics and human activity have contributed to visible changes on Rodas, Cíes Islands in southwestern Galicia (NW Spain). The number of visitors to the islands has increased in recent years, and the port infrastructure has therefore been expanded. Previously, this zone experimented with important sand extraction phases. These changes have influenced the ecosystem directly by modifying the sedimentary behavior and indirectly by promoting even greater numbers of visitors to the area. Aerial images and orthophotographs of the study zone were examined to identify changes that have taken place over the last sixty-one years (1956–2017). Changes in the position of the shoreline, defined as the boundary of the dune vegetation, were mapped at different times between 1956 and 2017. Changes in the shoreline were quantified using GIS (Geographic Information System) technology and Digital Shoreline Analysis System (DSAS) software. The findings revealed that the system regressed by more than 30 m between 1956 and 1981, in part as a result of sand extraction. We also identified different erosion/accretion phases that occurred before the reformation of the Rodas dock in 2010. The system is currently undergoing important changes, especially in the northern area, with a regression of 14.14 m in the last seven years. In this context, LiDAR analysis from 2010 and 2015 using Geomorphic Change Detection (GCD) tools allowed variations in the dune system to be verified. The elevation in the study zone increased in 83% of the area, mainly in the frontal dune and close to the winter inlet (north sector). However, the variations were very small. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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Review

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Open AccessFeature PaperReview

Hard-Rock Coastal Modelling: Past Practice and Future Prospects in a Changing World

by

Alan S. Trenhaile

J. Mar. Sci. Eng. 2019, 7(2), 34; https://doi.org/10.3390/jmse7020034 - 03 Feb 2019

Cited by 20 | Viewed by 3791

Abstract

This paper reviews the history of conceptual and numerical modelling of hard rock coasts (mean annual cliff erosion typically < 1 mm up to 1 cm) and its use in studying coastal evolution in the past and predicting the impact of the changing [...] Read more.

This paper reviews the history of conceptual and numerical modelling of hard rock coasts (mean annual cliff erosion typically < 1 mm up to 1 cm) and its use in studying coastal evolution in the past and predicting the impact of the changing climate, and especially rising sea level, in the future. Most of the models developed during the last century were concerned with the development and morphology of shore-normal coastal profiles, lacking any sediment cover, in non-tidal environments. Some newer models now consider the plan shape of rock coasts, and models often incorporate elements, such as the tidally controlled expenditure of wave energy within the intertidal zone, beach morphodynamics, weathering, changes in relative sea level, and the role of wave refraction and sediment accumulation. Despite these advances, the lack of field data, combined with the inherent complexity of rock coasts and uncertainty over their age, continue to inhibit attempts to develop more reliable models and to verify their results. Full article

(This article belongs to the Special Issue Coastal Morphodynamics II)

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