Efectos de temporales marítimos en sistemas litorales de la provincia de Cádiz

Las zonas litorales son ambientes dinámicos y cambiantes en donde los diversos procesos (e.g. físicos, químicos, biológicos) suelen desarrollarse rápidamente. Entre los elementos que contribuyen a la gran variabilidad de la zona litoral, los eventos extremos de oleaje (temporales, huracanes, tormentas tropicales, entre otros) son, quizás, los agentes que ocasionan los cambios más dramáticos, constituyendo además una de las principales fuentes de riesgo. La importancia de los eventos extremos de oleaje es tal que son considerados los principales responsables de la evolución de los sistemas de islas-barrera durante el Holoceno. De igual forma, se les asigna un papel principal en la evolución a largo plazo de las costas, a pesar de que su actuación está limitada a intervalos cortos de tiempo (Morton et al., 1995). Los ejemplos recientes de huracanes como Katrina (SE de EEUU, Agosto de 2005) y del ciclón Sidr (Bangladesh, Noviembre de 2007) confirman lo anteriormente mencionado. Además, dichos fenómenos han alertado a la opinión pública y a las diversas autoridades internacionales sobre los efectos devastadores de estos eventos, especialmente dañinos sobre costas bajas sobre todo ubicadas en países en vía de desarrollo. En términos ambientales y socioeconómicos, los eventos extremos de oleaje pueden llegar a ser considerados como generadores substanciales de riesgo debido a que su influencia puede llegar a afectar zonas densamente pobladas. Actualmente se estima que el 60% de la población del planeta vive a menos de 100 km del mar y los escenarios futuros prevén un aumento significativo de estos valores. Proyecciones efectuadas por las Naciones Unidas confirman lo antes mencionado, y a su vez, indican que el número de habitantes que se ubica en la franja costera podría alcanzar las tres cuartas partes (3/4) de la población mundial, equivalente a unos 4.500 millones de habitantes hacia el año 2020. En el caso de la Unión Europea, la costa se extiende a más de 100.000 km lo largo de 20 estados miembros (incluyendo España) y en el último medio siglo la población de las ciudades costeras se ha doblado hasta alcanzar 70 millones de personas en el año 2001 . De lo anterior, es indiscutible que esta concentración de la población en las áreas costeras está trayendo consigo un incremento en los riesgos asociados a los procesos generados por eventos extremos de oleaje. Este trabajo de tesis se ha enmarcado en parte dentro del proyecto ¿RESISTE: Mecanismos de Respuesta y Recuperación de Sistemas Litorales Frente a la Actuación de Temporales Marítimos¿ (CGL2008-00458) financiado por el Ministerio de Ciencia e Innovación y desarrollado dentro del Grupo de Geomorfología litoral de la Universidad de Cádiz. Dicho proyecto ha ido un paso adelante con respecto a otros proyectos desarrollados en el marco del mismo grupo: ¿Procesos de erosión costera en el litoral suratlántico español¿, ¿Análisis de la vulnerabilidad costera frente a la dinámica marina: implicaciones en la gestión del litoral suratlántico español¿ y ¿Riesgos geológicos costeros asociados a eventos energéticos marinos bajo diferentes regímenes maréales¿, financiados por el Ministerio de Educación y Ciencia. Estos proyectos se centraron en el análisis de los procesos físicos y sedimentarios involucrados en la erosión costera y en los ritmos naturales de cambio morfológico de las playas del Golfo de Cádiz. Estas investigaciones permitieron constatar que la evolución de la línea de costa presenta episodios críticos relacionados con eventos energéticos (fundamentalmente eventos extremos de oleaje), que dan lugar a cambios rápidos e intensos. En ocasiones, tras un evento energético, la llegada de nuevos temporales antes de que se recuperen los niveles volumétricos pre-evento da lugar a un déficit crónico, que deriva en una tendencia continua y a menudo irreversible de retroceso costero. En costas arenosas intensamente ocupadas, este mecanismo produce un rápido aumento de la vulnerabilidad costera y la consiguiente necesidad de abordar actuaciones de regeneración artificial, cuya vida media suele ser limitada. Además, los eventos energéticos de origen meteorológico también producen otros fenómenos peligrosos que generan claras situaciones de riesgo: desbordamientos del oleaje sobre frentes dunares (overwash), inundación de costas bajas debido a sobreelevación del nivel del mar (storm surge), entre otros. Dentro de este marco de referencia, el presente proyecto de Tesis Doctoral busca conocer la frecuencia, dinámica y efectos costeros de los eventos extremos de oleaje, así como los mecanismos mediante los cuales estos fenómenos pueden alterar la vulnerabilidad de la costa gaditana o sus tendencias evolutivas. Para esto se estudió el impacto de temporales concretos sobre tramos costeros tanto naturales como antropizados con diferentes características morfológicas, y se evaluaron las relaciones entre dichos cambios e indicadores climáticos de índole regional (e.g. NAO - North Atlantic Oscillation Index). Así mismo se determinaron los periodos de retorno ¿ probabilidades de ocurrencia de los eventos extremos de oleaje y se caracterizaron los cambios morfológicos registrados a lo largo de las últimas décadas y en especial de los últimos 3 años en las playas de Levante, Camposoto y La Cortadura, ubicadas todas dentro de la provincia de Cádiz

Coastal erosion monitoring in Colombia: overview and study cases on Caribbean and Pacific coasts

Tourism is one of the fastest growing activities in Colombia; the coast represents the favourite destination for both national and foreign visitors. However, coastal erosion is an actual problem, with high erosive rates in some areas. This chapter shows a general overview of the coastal erosion problem in Colombia and emphasizes the institutional framework used in monitoring. Four study cases are included to present a wide diagnosis of relevant erosive processes, both on Caribbean and Pacific coasts. Findings show erosive rates due to human interventions in all coastal departments on the Caribbean Sea; highest values were recorded in Cordoba (3.3 m/yr), Magdalena (5.3 m/yr) and La Guajira (3.2 m/yr). In addition, monitoring of barrier islands indicated that erosive processes on the Pacific coast are essentially due to natural phenomena, i.e. tsunami and El Niño events. In conclusion, long-term coastal erosion monitoring is urgently required in order to make adequate decisions and assess their effectiveness, with special concern to the correct location of coastal infrastructure and the management of coastal risks

Assessing and managing scenery of the Caribbean Coast of Colombia

This study provides the coastal scenery assessment of 135 sites along the Colombian Caribbean littoral by analysing 26 physical and human factors. Sites were categorised into five classes from Class 1, top grade scenery, to Class 5, poor scenery. Fifty five percent of the investigated coastal areas were included in Classes 1 and 2, 18% belonged to Class 3 and 47% of the sites fall into Classes 4 and 5. Classification of analysed sites depends on the geological setting and the degree of human occupation. Classes 1 and 2 sites are located in natural protected areas in La Guajira and Magdalena departments. Low classification recorded at Classes 3, 4 and 5 corresponds to a progressive decrease of both natural and (especially) human parameters. Concerning coastal management issues, emphasis should be given to the upgrading of human parameters eliminating litter and sewage evidences, vegetation debris and enhancing beach nourishment work

Morphological cells in the Ragusa littoral (Sicily, Italy)

Geomorphologic information, topographic maps (dated 1967), aerial photographs (dated 1999 and 2008), and spatial analysis procedures were used to investigate a 90 km long coastal sector in South Sicily (Italy). Information was obtained on coastal erosion/accretion areas, general sediment circulation pattern and littoral cell distribution. Human-made structures and natural headlands constituted important artificial limits dividing littoral in morphological cells. Ports and harbours were observed at Scoglitti, Punta Secca, Marina di Ragusa, Donnalucata and Pozzallo. Most of them worked as “transit” limits which interrupted predominant, eastward directed sedimentary transport, this way generating accretion in updrift (west) side of mentioned structures and erosion in downdrift (east) side. During the 1967–2008 period, about 62,000 m2 and 42,000 m2 of beach surface were respectively formed updrift of Scoglitti and Donnalucata ports. The construction of Pozzallo port gave rise to the formation of a “convergent” limit which favoured large accretion (94,000 m2) east of port structure. Most important natural structures were observed at Punta Zafaglione, P. Braccetto and Cava d’Aliga. The knowledge of littoral cell distribution acquires a great importance for appropriate management of coastal erosion processes which may be mitigated installing by-passing systems in ports and harbours and carrying out nourishment works in eroding areas, often located downdrift of ports and harbours (when these structures work as transit limits) and in central part of littoral cells (when these structures work as convergent limits)

On the status and mechanisms of coastal erosion in Marawila Beach, Sri Lanka

Coastal erosion remains a problem in many developing countries because of a limited understating of erosion mechanisms and management. Sri Lanka is one of the countries that recognized coastal erosion management as a governmental responsibility, in 1984. Nevertheless, erosion mechanisms have not yet been fully understood. We investigate the status and mechanisms of coastal erosion using empirically collected data and various techniques, such as Geographic Information System analysis of satellite images, drone mapping, bathymetric surveys, hindcasting of wind-induced wave climate, questionnaires, and semi-structured interview surveys. We identified wave climate change, reduction in river sand supply, interruptions from previous erosion management measures, and offshore sand mining as potential causes of erosion considering sediment flux and rates of erosion. Erosion of Marawila Beach began during 2005–2010 and has been continuing ever since, due to a lack of integration in the beach and the entire sediment system. It is necessary to identify the long-term, large-scale changes in the sediment system through data collection. This study highlights the importance of an integrated coastal erosion management plan and could facilitate better coastal erosion management in Sri Lanka, as well as in other developing countries

Confirmation of beach accretion by grain-size trend analysis: Camposoto beach, Cádiz, SW Spain

An application of the grain size trend analysis (GSTA) is used in an exploratory approach to characterize sediment transport on Camposoto beach (Cádiz, SW Spain). In May 2009 the mesotidal beach showed a well-developed swash bar on the upper foreshore, which was associated with fair-weather conditions prevailing just before and during the field survey. The results were tested by means of an autocorrelation statistical test (index I of Moran). Two sedimentological trends were recognized, i.e. development towards finer, better sorted and more negatively skewed sediment (FB–), and towards finer, better sorted and less negatively or more positively skewed sediment (FB+). Both vector fields were compared with results obtained from more classical approaches (sand tracers, microtopography and current measurements). This revealed that both trends can be considered as realistic, the FB+ trend being identified for the first time in a beach environment. The data demonstrate that, on the well-developed swash bar, sediment transported onshore becomes both finer and better sorted towards the coast. On the lower foreshore, which exhibits a steeper slope produced by breaking waves, the higherenergy processes winnow out finer particles and thereby produce negatively skewed grain-size distributions. The upper foreshore, which has a flatter and smoother slope, is controlled by lower-energy swash-backwash and overwash processes. As a result, the skewness of the grain-size distributions evolves towards less negative or more positive values. The skewness parameter appears to be distributed as a function of the beach slope and, thus, reflects variations in hydrodynamic energy. This has novel implications for coastal management

Variability in storm climate along the Gulf of Cadiz: the role of large scale atmospheric forcing and implications to coastal hazards

In the context of increased coastal hazards due to variability in storminess patterns, the danger of coastal damages and/or morphological changes is related to the sum of sea level conditions, storm surge, maximum wave height and run up values. In order to better understand the physical processes that cause the variability of the above parameters a 44 years reanalysis record (HIPOCAS) was used. The HIPOCAS time-series was validated with real wave and sea-level data using linear and vector correlation methods. In the present work changes in the magnitude, duration, frequency and approach direction of the Atlantic storms over the Gulf of Cadiz (SW Iberian Peninsula) were identified by computing various storm characteristics such as maximum wave height, total energy per storm wave direction and storm duration. The obtained time-series were compared with large-scale atmospheric indices such as the North Atlantic Oscillation (NAO) and the East Atlantic pattern. The results show a good correlation between negative NAO values and increased storminess over the entire Gulf of Cadiz. Furthermore, negative NAO values were correlated with high residual sea level values. Finally, a joint probability analysis of storm and sea level analysis resulted in increased probabilities of the two events happening at the same time indicating higher vulnerability of the coast and increased coastal risks. The above results were compared with coastal inundation events that took place over the last winter seasons in the province of Cadiz.info:eu-repo/semantics/publishedVersio

Analyzing the impact and evolution of ocean & coastal management: 30 years in retrospect

Ocean & Coastal Management (OCMA) has significantly contributed to international ocean and coastal management, policy-making, governance, and other related research fields. This article highlights the contributions OCMA has made in these areas by summarizing the trends in 3782 articles published from 1992 to 2021. Using bibliometric and knowledge graph visualization analyses, this article systematically reviews the historical research contributions in each field and identifies emerging topics in recent years, such as the Blue Economy, shipping, and marine litter. OCMA has made a substantial positive impact on global ocean and coastal management by fostering collaboration among scholars and practitioners, advancing policy and regulatory development, enhancing management practices, increasing public awareness of environmental protection, and promoting sustainable development. In addition to its critical academic role in the field of ocean and coastal management, OCMA has also facilitated advancements in related research and practice (such as coastal erosion, litter, port management), ultimately contributing to the protection of global ocean and coastal ecosystems

A rapid assessment of litter magnitudes and impacts along the Torre Guaceto marine protected area (Brindisi, Italy)

This study focuses on assessing litter magnitudes along the Torre Guaceto Marine Protected Area (Brindisi, Italy). Collected litter was grouped into twenty different types and classified into four litter typologies according to the Guidance on Monitoring of Marine Litter in European Seas. All data were analyzed using an index-based approach that allowed the classification of a coastal stretch in terms of cleanliness, and presence of plastics as well hazardous items. The average litter abundance in the study area was 0.5 items/m2, being plastics the most common litter item. Hazardous litter items were found along the study area, reaching 21.3% of the total collected items. The application of environmental indices allowed to define the study area with a “moderate cleanliness” and a “moderate” presence of hazardous litter items. Sampled litter typologies and related magnitudes suggest a combination of sources that mainly include direct activities on the nearby coastal zones and river basins (dumping)