The complexity of studying coasts: From forms and processes to management

Coastal environments are characterized by their high dynamism, related to the interaction between marine agents (winds, waves, currents, sea level changes) and continental forms and processes. The present article summarizes the main morphodynamic characteristics of coasts and the resulting environments. Different oscillations of the sea level are considered, depending on their amplitude and frequency: rapid eustatic fluctuations, energetic tsunamis, storm waves and surges, tides and good weather wind waves. Coastal environments are classified in low, sedimentary coasts, including beaches, dunes, barrier islands, lagoons, salt marshes and river mouths, and high, rocky coasts. Management of coastal zones needs a deep knowledge of all the processes involved at the littoral, especially at the local scale, since coastal processes vary rapidly alongshore. At present the integrated coastal management intends to involve different socioeconomic sectors interested in the occupation and use of coasts. Coastal management must include the adaptation of human activities to the natural processes and associated coastal hazards and the protection of coastal values, both of natural and historical-cultural character. Public administrations at different levels should consider the knowledge of the coastal processes at different scales and their potential interaction with human activities in order to design laws and regulations accordingly

Evolución Geomorfológica de la región de Gallocanta (Cordillera Ibérica Central)

The paper represents a summary of the Doctoral Thesis of the author. It deals with several aspects related to the regional and evolutive geomorphology of the central sector of the Iberian Chain: neogene erosion surfaces, karst landforms, pediment deposits, fluvial terraces, endorheism and lacustrine deposits. Finally, the geomorphological evolution of the studied area is established, which is controlled by the neogene neotectonic activity and quaternary climatic evolution.Se ofrece un resumen de la tesis doctoral del autor, en la que se estudian diversos aspectos de la geomorfología regional y evolutiva del sector central de la cordillera ibérica: suerficies de erosión neógenas, modelado karstico, depósitos de piedemonte (glacis), terrazas fluviales, endorreismo y depósitos lacustres. Se establece finalmente la evolución geomorfológica del área de estudio, controlada en buena medida por la actividad tectónica neógena y por la evolución climática cuaternaria

Estuarine Mapping and Eco-Geomorphological Characterization for Potential Application in Conservation and Management: Three Study Cases along the Iberian Coast

Geomorphological changes in recent decades in three estuaries along the Iberian coast were analysed using aerial orthophotographs. A hierarchical classification scheme, based on a literature review representing 26 estuarine eco-geomorphological features relevant to estuarine dynamics and functioning, is described. The estuaries selected were San Vicente de la Barquera (N Spain), Guadiana River (SW border between Spain and Portugal) and the Ebro River Delta mouth (NE Spain). For these systems, a 60-year time series of high-resolution maps was developed, analysing the changes in feature surfaces. The main subsystems analysed were beach, dunes, saltmarshes and the drainage network. The results of the cartographies showed general behaviour common to all transitional systems, relationships among main subsystems and processes inherent to each one. This work illustrates how beaches and dunes serve as a protective barrier for the tidal flats, acting as a sediment buffer for the entire system. The subsystems are connected by the drainage network responsible for the exchange of matter and energy between them. Furthermore, an accuracy assessment was performed in one of the study zones to identify the limitations of mapping with aerial photographs. The results explain the changes with time but also the processes and relationships between the estuarine features at a long-term scale. This work adds an important perspective towards a general understanding of their dependence on intrinsic and boundary conditions

Fluvial base level control on the differential rejuvenation of the Olvera- Zaframagón gypsum karst system (NE Cádiz province)

El presente trabajo analiza la evolución del relieve en un sector localizado entre la depresión del Guadalquivir y la cuenca de Ronda, en la Cordillera Bética noroccidental, representado por extensos afloramientos de arcillas y yesos triásicos, sobre los que destacan relieves rocosos aislados formados por bloques de calizas jurásicas, como el peñón de Zaframagón, al oeste del municipio de Olvera. Estos bloques dibujan una antigua superficie de erosión con pendiente hacia el NO, muy probablemente asociada a la progresiva continentalización de la cuenca del Guadalquivir durante el Plioceno. Los afloramientos triásicos están afectados por una intensa karstificación en forma de dolinas y simas y otras depresiones de fondo plano, de tipo polje, en las zonas interfluviales. La incisión diferencial de los ríos Guadamanil y Guadalporcún, en la parte alta de la cuenca del río Guadalete, parece haber condicionado el desarrollo vertical de las formas kársticas. El río Guadalporcún corta transversalmente al peñón de Zaframagón a través de un corto pero profundo cañón, que ha actuado como obstáculo a la incisión del río, lo que ha provocado una menor tasa de encajamiento con respecto al río Guadamanil. Este encajamiento diferencial ha afectado al desarrollo de las formas kársticas de absorción que drenan a uno y otro río, generando simas más profundas en la vertiente que drena al Guadamanil. Por otro lado, en las laderas del valle de este río se ha reconocido una secuencia de surgencias escalonadas, cuyas alturas con respecto al cauce coinciden con las alturas generales asignadas a los niveles de terrazas cuaternarias definidos para la cuenca fluvial del Guadalete. Todos estos aspectos apuntan a que el desarrollo vertical del karst de Olvera-Zaframagón durante el Pleistoceno ha estado muy condicionado por el comportamiento del nivel de base, tanto a escala regional como local.The present work deals with the relief evolution in an area of the northwestern sector of the Betic Ranges. It is characterized by extensive outcrops of Triassic clays and gypsums over which several isolated reliefs of Jurassic carbonate rocks stand out, like the Zaframagón Rock, West of Olvera village. The flattened summits of all these carbonate blocks delimit an old erosion surface sloping NW, very probably related to the progressive continentalization of the nearby, formerly marine, Guadalquivir Tertiary Depression during the Pliocene. The Triassic gypsums are presently affected by intense karstification in form of dolines and shafts, as well as other flat-bottomed depressions similar to poljes in the interfluve areas. Differential incision in the Guadamanil and Guadalporcún Rivers, located in the head of the Guadalete fluvial basin, seems to have conditioned the vertical development of karst forms in the region. The Guadalporcún River crosses the Zaframagón Rock through a short but deep gorge. The Rock has acted as an obstacle to the river incision and this has hampered its vertical erosion if compared to the one of the Guadamanil River. This differential incision has affected the development of absortion karst forms which drain to both rivers: dolines and shafts are deeper when draining to the Guadamanil River valley. The slopes of the valley are plenty of active and inactive springs, drawing a sequence of stepped outflow points, whose relative heights coincide with the general heights assigned to the Quaternary fluvial terrace levels regionally defined for the Guadalete River basin. All these aspects suggest a strong relationship between the Pleistocene vertical development of the Olvera-Zaframagón karst system and the behavior of the base level, both at regional and local levels

Historical morphological changes (1956-2017) and future trends at the mouth of the Ebro River delta (NE Spain)

The present work focuses on the recent morphological changes recorded in the Ebro River delta, by using aerial photographs in the last six decades and by analyzing changes in the main constitutive features through geomorphological maps. Geomorphological maps of the years 1956 and 2017 are here presented. The results obtained give very valuable clues about the recent trends of the river delta mouth, which can be used to predict future coastal changes to be expected in the following decades. In this sense, by analysing changes in the surface by means of the geomorphological maps together with a shoreline analysis, a differential behavior has been described at both sides of the river mouth: the left side, El Garxal wetland, shows an accretionary trend with rates reaching +40 m/year, while the right side, San Antonio Island, shows erosive trends of more than -20 m/year. This last side also presents a surface reduction of more than 50 ha in the last 60 years. These results suggest that, approximately by the year 2050, the emerged San Antonio Island may disappear if shoreline retreat trends are maintained, making El Garxal exposed to easterly storms, the main erosive dynamic processes in this zone and, therefore changing the entire configuration of the Ebro River delta mouth in the upcoming years. Despite possible solutions have been described in recent works, they may not contribute to a total recovery of the most natural part of the Ebro Delta. Urgent management plans are required to attempting to slow or reverse these trends, otherwise one of the most valuable ecosystems of the delta could disappear

The Mediterranean Coast of Andalusia (Spain): Medium-Term Evolution and Impacts of Coastal Structures

This paper shows coastal evolution along the Andalusia Region (Spain) and the impacts on it of coastal structures. The study area was divided into 47 units to calculate the erosion/accretion/stability (or evolution) rates by using the DSAS extension of ArcGIS software. Evolution rates were divided into different classes from “Very high accretion” to “Very high erosion”. As a result, 9 units recorded accretion, 19 stability and 19 erosion. Further, 17 units presented a positive balance and 28 units a negative one, showing a negative net balance of 29,738.4 m2/year corresponding to the loss of 1784.30 km2 of beach surface in the 1956–2016 period. The distribution of evolution areas along the studied coast was carried out by means of the “R” project for statistical computing. The analysis evidenced the impact of rigid structures: accretion was essentially observed up-drift of ports and groins and in correspondence of protection structures, especially of breakwaters. Erosion classes were observed down-drift of ports and groins and in correspondence of revetments/seawalls, and at largest river deltas, and “stability” was observed at pocket beaches and coastal areas locally stabilized by protection structures. Last, results were used to determine the distribution of swash- and drift-aligned coastal sectors and main direction of sedimentary transport

Reconstructing the historical shoreline evolution of the Northern Bay of Cádiz (SW Spain) from geomorphological and geoarchaeological data

During the last 3 ka, different human communities occupied the Bay of Cádiz (SW Spain), including Phoenician, Carthaginian, Roman, Medieval and Modern settlements. Traces of such historical occupations have been recognized along the bay from a geoarchaeological point of view. Some of them bear a palaeogeographical interest related to the historical location of the shoreline. At the same time, Holocene sedimentary units and geomorphological elements identified along the bay can be interpreted as evidences of its morphological evolution. The objective of the present paper is to represent all the available data about archaeological sites and geomorphology in the northern Bay of Cádiz, with the aim of combining both sources of data for elaborating a simple proposal of landscape evolution during the last 3 millennia. The base for mapping was multiple, from historical aerial photographs to satellite imagery and a digital terrain model with a maximum resolution of 0.35 m.12 página

Evolución histórica de la línea de costa en el sector meridional de la bahía de Cádiz

Los cambios paleogeográficos que han afectado históricamente a la Bahía interna de Cádiz han estado condicionados por la variación relativa del nivel del mar, por los cambios climáticos, por la actuación puntual de eventos energéticos (tsunamis, temporales marítimos) y por la actividad humana. Los cambios climáticos han sido especialmente determinantes, ya que han controlado la frecuencia de llegada de los temporales marítimos erosivos, así como la instalación de condiciones meteorológicas que favorecen el desarrollo de sistemas dunares activos

Fish farming in «Baetica». The «piscine» of the halieutic site at Trafalgar Cape (Cádiz)

The present paper presents a structure of Roman date, cut into bedrock, and possibly used for fish farming purposes. So far, this sort of evidence, which is well attested in Italian villae maritimae dating to the Late Republic and the Early Empire, had only been found in the Iberian Peninsula in the southern Tarraconense (coast of Alicante). The above mentioned structure is, therefore, the first of its kind found in the Baetica. Interpretation must combine archaeological evidence for Roman fish farming in Andalusia (ostrearum vivaria at Traducta, current Algeciras) and geoarchaeological features; the structure is located in the intertidal zone and enjoys fresh water supply from the nearby halieutic site of Trafalgar Cape (Barbate, Cádiz). This paper aims at the re-interpretation of this coastal site, previously interpreted as a salted products factory, or cetaria, but the topographical and architectural features of which (vats with inner steps, cisterns, terraced structures, etc.) are rather suggestive of a villa maritima or a complex centre for the exploitation of marine resources.Se presenta a continuación una estructura excavada en la roca interpretada como un posible vivero romano destinado a tareas de acuicultura, constituyendo la primera evidencia de estas características en Baetica, pues hasta la fecha solamente se disponía de piscinae construidas siguiendo esta conocida costumbre vinculada a las villae maritimae itálicas de la Tardía República e inicios del Alto Imperio en la Tarraconense meridional (costa de Alicante). Junto al análisis de las evidencias arqueológicas relacionadas con acuicultura romana en Andalucía (ostrearum vivaria de Traducta, actual Algeciras) se presenta la problemática arqueológica y geoarqueológica de este hallazgo situado en un área intermareal, con aporte de agua dulce, vinculado al yacimiento haliéutico del Cabo Trafalgar (Barbate, Cádiz). Se plantean propuestas sobre la interpretación de este yacimiento costero, tradicionalmente considerado como una factoría de salazones o cetaria, cuyas singularidades topográficas y arquitectónicas (piletas escalonadas, aljibe y disposición en terrazas) inducen a pensar más bien en una villa maritima o en un centro de explotación de recursos marinos de gran complejidad

Fish farming in «Baetica». The «piscine» of the halieutic site at Trafalgar Cape (Cádiz)

The present paper presents a structure of Roman date, cut into bedrock, and possibly used for fish farming purposes. So far, this sort of evidence, which is well attested in Italian villae maritimae dating to the Late Republic and the Early Empire, had only been found in the Iberian Peninsula in the southern Tarraconense (coast of Alicante). The above mentioned structure is, therefore, the first of its kind found in the Baetica. Interpretation must combine archaeological evidence for Roman fish farming in Andalusia (ostrearum vivaria at Traducta, current Algeciras) and geoarchaeological features; the structure is located in the intertidal zone and enjoys fresh water supply from the nearby halieutic site of Trafalgar Cape (Barbate, Cádiz). This paper aims at the re-interpretation of this coastal site, previously interpreted as a salted products factory, or cetaria, but the topographical and architectural features of which (vats with inner steps, cisterns, terraced structures, etc.) are rather suggestive of a villa maritima or a complex centre for the exploitation of marine resources.Se presenta a continuación una estructura excavada en la roca interpretada como un posible vivero romano destinado a tareas de acuicultura, constituyendo la primera evidencia de estas características en Baetica, pues hasta la fecha solamente se disponía de piscinae construidas siguiendo esta conocida costumbre vinculada a las villae maritimae itálicas de la Tardía República e inicios del Alto Imperio en la Tarraconense meridional (costa de Alicante). Junto al análisis de las evidencias arqueológicas relacionadas con acuicultura romana en Andalucía (ostrearum vivaria de Traducta, actual Algeciras) se presenta la problemática arqueológica y geoarqueológica de este hallazgo situado en un área intermareal, con aporte de agua dulce, vinculado al yacimiento haliéutico del Cabo Trafalgar (Barbate, Cádiz). Se plantean propuestas sobre la interpretación de este yacimiento costero, tradicionalmente considerado como una factoría de salazones o cetaria, cuyas singularidades topográficas y arquitectónicas (piletas escalonadas, aljibe y disposición en terrazas) inducen a pensar más bien en una villa maritima o en un centro de explotación de recursos marinos de gran complejidad