1,721,093 research outputs found
Coastal dynamic and evolution: Case studies from different sites around the world
No full textIn recent decades, coastal areas have experienced a progressive increase in erosion and flooding processes as a consequence of the combined effect of natural factors and strong human pressures. These processes are particularly evident on low-lying areas and are expected to be exacerbated by the ongoing climate change, which will impact the littorals both in the short term, by affecting the duration and frequency of storms, and in the long term, by inducing variation in the sea-level position. In this context, this Special Issue is devoted to collecting geomorphological studies on coastal dynamic and evolution by means of multidisciplinary research methodologies and investigations, which represent a very useful set of information for supporting the integrated management of coastal zone. The volume includes 14 papers addressing three main topics (i) shoreline characterization, dynamic and evaluation; (ii) coastal hazard evaluation and impact assessment of marine events; and (iii) relevance of sediment collection and analysis for beach nourishment. Case studies from Russia, Italy, California (USA), Morocco, Spain, Indonesia, Ireland and Colombia are shown in the Special Issue, giving to the reader a wide overview of coastal settings and methodological approaches
Processus de migration des barres intertidales sous l’impact du “swash”. Etudes en Adriatique septentrionale.
No full textCoastal sensitivity/vulnerability characterization and adaptation strategies: A review
Full text linkCoastal area constitutes a vulnerable environment and requires special attention to preserve ecosystems and human activities therein. To this aim, many studies have been devoted both in past and recent years to analyzing the main factors affecting coastal vulnerability and susceptibility. Among the most used approaches, the Coastal Vulnerability Index (CVI) accounts for all relevant variables that characterize the coastal environment dealing with: (i) forcing actions (waves, tidal range, sea-level rise, etc.), (ii) morphological characteristics (geomorphology, foreshore slope, dune features, etc.), (iii) socio-economic, ecological and cultural aspects (tourism activities, natural habitats, etc.). Each variable is evaluated at each portion of the investigated coast, and associated with a vulnerability level which usually ranges from 1 (very low vulnerability), to 5 (very high vulnerability). Following a susceptibility/vulnerability analysis of a coastal stretch, specific strategies must be chosen and implemented to favor coastal resilience and adaptation, spanning from hard solutions (e.g., groins, breakwaters, etc.) to soft solutions (e.g., beach and dune nourishment projects), to the relocation option and the establishment of accommodation strategies (e.g., emergency preparedness)
Medium-term shoreline evolution of the mediterranean coast of Andalusia (SW Spain)
No full textCoastal environment is a dynamic system in which numerous natural processes are continuously actuating
and interacting among them. As a result, geomorphologic, physical and biological characteristics of coastal
environments are constantly changing. Such dynamic balance is nowadays seriously threatened by the strong and
increasing anthropic pressure that favors erosion processes, and the associated loss of environmental, ecologic and
economic aspects. Sandy beaches are the most vulnerable environments in coastal areas.
The aim of this work was to reconstruct the historical evolution of the Mediterranean coastline of Andalusia,
Spain. The investigated area is about 500 km in length and includes the provinces of Cadiz, Malaga, Granada
and Almeria. It is essentially composed by cliffed sectors with sand and gravel pocket beaches constituting
independent morphological cells of different dimensions.
This study was based on the analysis of aerial photos and satellite images covering a period of 55 years, between
1956 and 2011. Aerial photos were scanned and geo-referenced in order to solve scale and distortion problems.
The shoreline was considered and mapped through the identification of the wet / dry sand limit which coincides
with the line of maximum run-up; this indicator - representing the shoreline at the moment of the photo - is
the most easily identifiable and representative one in microtidal coastal environments. Since shoreline position
is linked to beach profile characteristics and to waves, tide and wind conditions at the moment of the photo,
such parameters were taken into account in the calculation of shoreline position and changes. Specifically,
retreat/accretion changes were reconstructed applying the DSAS method (Digital Shoreline Analysis System)
proposed by the US Geological Survey.
Significant beach accretion was observed at Playa La Mamola (Granada), with +1 m/y, because the construction
of five breakwaters, and at Playa El Cantal (Almeria) and close to Garrucha harbor, with values of +2 m/y.
Erosion rates ranged from -0.4 m/y (at Playa Casarones, Rubite) and -0.7 m/y (at Playa Castillos de Baños,
Granada) to c. -2 m/y (at Punta de los Hornicos, Almeria).
The analysis of coastline evolution revealed as the distribution of erosion areas is strictly related to the incorrect
design of coastal structures and their negative effects on downdrift areas. Obtained results clearly evidenced as, in
order to evaluate the efficiency of emplaced coastal defense structures, a continuous coastal evolution monitoring
plan should be implemented
A Methodological Tool to Assess Erosion Susceptibility of High Coastal Sectors: Case Studies from Campania Region (Southern Italy)
No full textHigh coastal sectors constitute the most widespread coastal environment and, under the present accelerated sea-level rise scenario, are suffering huge impacts in terms of erosion. The aim of this paper is the proposal of a new methodological approach for the assessment of their susceptibility to erosive processes. The method is based on the combination of two matrices, i.e., a matrix considering the main physical elements (essentially morphological and geotechnical characteristics) that determine the proneness to erosion of a specific high coastal sector, and a forcing matrix, which describes the forcing agents affecting the considered sector. Firstly, several variables were selected to construct each one of the two matrices according to existing studies and, in a second step, they were interpolated to obtain the susceptibility matrix (CSIx). The approach was applied to Procida Island and Cilento promontory, both located in southern Italy. Results obtained were validated by comparing them with cliff retreat data obtained by means of aerial photographs and satellite images. The analysis shows that the greater part of the analyzed high coastal sectors belongs to the high-susceptibility class due to the combination of adverse morphological, geotechnical and forcing characteristics. Such sectors can be considered "hotspots" that require an increase in monitoring programs and, at places, urgent protective actions
Relationship between bar migration and swash duration: field assessments at Lido di Volano beach, Adriatic Sea, Northern Italy
No full textThe mediterranean coast of Andalusia (sw spain): the impacts of human coastal structures
No full textSpanish coasts, especially the Andalusia Mediterranean one, were affected over time by progressive urbanization
and associated construction of defense structures. Such structures protected small coastal sectors but at places
triggered processes of coastal erosion and associated degradation of habitats and ecosystems. A correct management
of coastal areas must be based on the monitoring of coastal evolution and human pressure. A useful tool to
evaluate the level of human anthropization is the estimation of the "Coastal Armouring", e.g. the quantification of
coastal defense structures, infrastructures, ports, etc.
In this study, available aerial photographs and satellite images from 1956 to 2011 were scanned and geo-referenced
and used for the quantitative assessment of coastal human constructions impact on the studied coastal area. The so
called coefficient of technogenous impact (K) was used. It results from the relationship between the total length
of all maritime structures (groins, moles, seawalls, dikes, channels, etc.) and the entire length of the study coastal
section. For this purpose, the Andalusia coast, about 500 km in length, was divided into sections of 1 km. For each
one of such sections the technogenous impact was calculated in the 1956 and 2011 documents.
The analysis showed that the degree of anthropization in some areas (for example the Port of Montril) has
increased considerably, triggering degradation processes in the nearby coastal areas. Results also evidenced as, in
many cases, greatest human impacts are linked to the progressive construction of coastal defense.
The lack of a general strategy to combat the erosion problem and the urgency in the short term to protect specific
parts of the coast led to a reactive approach based initially in the construction of hard structures. Such interventions
locally solved erosion problems but gave rise to drowndrift erosion according to the “domino” effect. A more
general management plan is needed, essentially based on the by-pass of ports and harbors and beach nourishment
works
Caracterización y evolución del sistema playa-duna de la costa mediterránea de andalucía (España): influencia de procesos naturales y actuaciones antrópicas
Full text linkIn past decades coastal, erosion related impacts on the world’s shorelines have been significantly growing due to ongoing coastal development and tourist occupation as well as to natural erosion/flooding events exacerbated by climatic change. Ocean coastlines are highly dynamic and changing environments since they show great temporal and spatial variability in response to the action of different and complex coastal processes: at an inter-annual time scales, related to seasonal wave climate variations due to temporal and spatial distributions of high latitude storms and tropical storms/hurricanes, or as a result of events with a large return period, such as the impact of very energetic storms and tsunamis, sea level rise, and variations in rivers’ sediment supplies. In order to prevent and reduce such impacts, coastal managers need to know the sensitivity of natural coastal sectors, which is related to wave energy, beach characteristics/evolution, and sea level trend as well as the potential vulnerability and economic value of the urbanized sectors.
This paper shows coastal evolution and the impacts on it of coastal structures and the characterization and evolution of dune systems along the Mediterranean coast of Andalusia (Spain). For this purpose, an amount of 47 units were defined along the studied coast, and evolution rates (erosion/accretion/stability), for the period 1956-2016, quantified by using the DSAS extension of ArcGIS software. As a result, 9 units recorded accretion, 19 erosion and 19 stability and, concerning the beach surface balance, 17 units presented a positive balance and 28 a negative one and a net balance of -29,738.4 m2/yr. The analysis of coastal evolution evidenced the impact of hard structures: accretion was essentially observed up-drift of ports and groins and in correspondence of breakwaters; erosion was observed down-drift of ports and groins and in correspondence of seawalls and revetments, and at largest river deltas; and stability was observed at pocket beaches and coastal areas locally stabilized by protection structures and nourishment works. These results were used to determine the distribution of swash- and drift-aligned coastal sectors and main direction of sediment transport.
Concerning the characterization and evolution of dune systems, they were mapped different type dunes’ systems as well as dune toe position and fragmentation, and human occupation and evolution from 1977 to 2001 and from 2001 to 2016. In total, they were delimited 53 dune systems along the Mediterranean coast of Andalusia, differentiating three types: Embryo and mobile dunes, grass-fixed dunes and stabilized dunes. It was observed a general decrease in dunes’ surfaces in the 1977-2001 period (-7.5 x 106 m2), linked to the increase of anthropic occupation (+2.3 x 106 m2), and dunes’ fragmentation, especially in Málaga and Almería provinces. During the 2001-2016 period, smaller changes in the level of fragmentation and in dunes’ surfaces were observed. An increase of dunes’ surfaces was only observed on stable or accreting beaches (4 out of 53 dune systems), both in natural and anthropic areas (usually up-drift of ports)
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