Process-based indicators to assess storm induced coastal hazards

Storms are responsible for several hazards (e.g. overwash, erosion, inundation) in coastal areas, leading to the destruction of property and loss of life in populated areas. Various indicators are used to express potential storm impact and describe the associated hazards. The most commonly used indicators include either forcing parameters (e.g. wave height, sea level) or coastal morphologies (e.g. dune height or berm width). Whereas they do not represent the processes associated with storm induced hazards in coastal areas. Alternatively, a hazard could be better characterised if process-based indicators are used instead. Process-based indicators express the result of the forcing mechanisms acting over the coastal morphology and reflect both hydrodynamic and morphological characteristics. This work discusses and synthesizes the most relevant process-based indicators for sandy shores subject to overwash, erosion and inundation promoted by storms. Those include: overwash depth, potential and extent; shoreline, berm or dune retreat; vertical erosion; and inundation depth and extent. The selection of a reduced set of process-based indicators to identify coastal hazards induced by storms in sandy coasts will facilitate comparison of different coastal behaviours for distinct storm return periods, and help to optimise coastal management plans, thereby contributing to the reduction of coastal risks.info:eu-repo/semantics/publishedVersio

Modeling of Coastal Erosion in Exposed and Groin-Protected Steep Beaches

Process-based models are suitable tools for reproducing storm-driven erosion. However, their performance has been mainly examined on mild-slope sandy beaches and their use on steep beaches still represents a challenge. Here, open-source process-based model XBeach experiments were combined with topographical measurements collected for two storms (16- and 5-year return period) to obtain a reliable model. The model parameters "facua"(parameterized wave asymmetry and skewness sediment transport component), "bermslope"(upslope transport term for semireflective beaches), and "wetslope"(critical avalanching submerged slope) were utilized for calibration and validation. The 16-year storm simulations on an exposed beach revealed that whether bermslope increased and "facua"must be reduced, and vice versa, to properly simulate erosion. Adding bermslope provided excellent results for these storms when using facua and wetslope values close to the recommended values. In a groin-protected site, XBeach was successfully calibrated and validated for the tested storms using these parameters, although with different values. These experiments demonstrated that the appropriate use of these parameters can satisfactorily simulate morphological changes on steep beaches for different hydrodynamic conditions and coastal settings (exposed and groin protected). © 2022 This work is made available under the terms of the Creative Commons Attribution 4.0 International license

Modeling of coastal erosion in exposed and groin-protected steep beaches

Process-based models are suitable tools for reproducing storm-driven erosion. However, their performance has been mainly examined on mild-slope sandy beaches and their use on steep beaches still represents a challenge. Here, open-source process-based model XBeach experiments were combined with topographical measurements collected for two storms (16- and 5-year return period) to obtain a reliable model. The model parameters “facua” (parameterized wave asymmetry and skewness sediment transport component), “bermslope” (upslope transport term for semireflective beaches), and “wetslope” (critical avalanching submerged slope) were utilized for calibration and validation. The 16-year storm simulations on an exposed beach revealed that whether bermslope increased and “facua” must be reduced, and vice versa, to properly simulate erosion. Adding bermslope provided excellent results for these storms when using facua and wetslope values close to the recommended values. In a groin-protected site, XBeach was successfully calibrated and validated for the tested storms using these parameters, although with different values. These experiments demonstrated that the appropriate use of these parameters can satisfactorily simulate morphological changes on steep beaches for different hydrodynamic conditions and coastal settings (exposed and groin protected).info:eu-repo/semantics/acceptedVersio

Erasmus experience between the University of Cadiz (Spain) and the University of Algarve (Portugal)

A mobility program was carried out during the last two years between the Universities of Cadiz (Spain) and Algarve (Portugal) under the EU funded Erasmus+ Mobility for Teaching. The objective of the mobility was twofold: on one hand, it included the strengthening of the existing scientific cooperation between the University of Cadiz (home institution) and the University of Algarve (host institution) in the field of the Gulf of Cadiz Physical Oceanography; on the other hand, it pretended to improve the teaching quality, focusing on both the lecturers and the students. Both institutions have long ties of cooperation that have recently been intensified under the umbrella of the International Campus of Marine Excellence (CeiMar). Specific objectives oriented towards the lecturers included the exchange of teaching experiences among them as well as the comparison of teaching strategies and methodologies between the host and home institutions at the Master level in order to evaluate and enhance the best teaching practices with the aim of improving the students learning process. Specific objectives oriented towards the students included: (1) to provide local students that cannot afford studying a Master degree abroad with a foreign teacher in the discipline that will offer them different added expectations; (2) to teach students different subjects from those taught at the host institution, thus benefitting from new scientific knowledge and experiences. It must be pointed out that the subject taught by the home institution lecturer represents a competence lacking at the host institution, hence complementing the program of the discipline and providing an added value to the Master degree. Informal questionnaires carried out among students by the host institution revealed that they evaluated having a foreign teacher as a very positive experience. In terms of research, collaboration among both institutions is of great importance because they are both located within the same geographic region and hence, they share common interests. The mobility promoted finishing on-going collaborative publications as well as sharing new research experiences, data and knowledge, hence leading to an improvement of the Physical Oceanography state-of-the-art in the Gulf of Cadiz. In fact, two scientific papers on the Gulf of Cadiz circulation system and two on the storm climate along the Gulf of Cadiz and its relation with coastal hazards have been recently published as a direct result of the mobility program.info:eu-repo/semantics/publishedVersio

Assessing the effects of Tidal Energy Converter array size on hydrodynamics of Ria Formosa (Portugal)

info:eu-repo/semantics/publishedVersio

Estimating the optimum size of a tidal array at a multi-inlet system considering environmental and performance constraints

This paper investigates the optimum tidal energy converter array density at a tidal inlet by applying surrogate-based optimisation. The SBO procedure comprises problem formulation, design of experiments, numerical simulations, surrogate model construction and constrained optimisation. This study presents an example for the Faro-Olhão Inlet in the Ria Formosa (Portugal), a potential site for tidal in-stream energy extraction. A 35 kW Evopod™ floating tidal energy converter from Oceanflow Energy Ltd. has been used for array size calculations considering two design variables: (1) number of array rows, and (2) number of tidal energy converter per row. Arrays up to 13 rows with 6–11 tidal energy converters each are studied to assess their impacts on array performance, inlets discharges and bathymetry changes. The analysis identified the positive/negative feedbacks between the two design variables in real case complex flow fields under variable bathymetry and channel morphology. The non-uniformity of tidal currents along the array region causes the variability of the resource in each row, as well as makes it difficult to predict the resultant array configuration interactions. Four different multi-objective optimisation models are formulated subject to a set of performance and environmental constraints. Results from the optimisation models imply that the largest array size that meets the environmental constraints is made of 5 rows with 6 tidal energy converter each and an overall capacity factor of 11.6% resulting in an energy production of 1.01 GWh year−1. On the other hand, a higher energy production (1.20 GWh year−1) is achieved by an optimum array configuration, made of 3 rows with 10 tidal energy converters per row, which maximises power output satisfying environmental and performance restrictions. This optimal configuration permits a good level of energy extraction while having a reduced effect on the hydrodynamic functioning of the multi-inlet system. These results prove the suitability and the potential wide use of the surrogate-based optimisation method to define array characteristics that enhance power production and at the same time respect the environmental surrounding conditions.info:eu-repo/semantics/publishedVersio

Development of tutorials to promote self-directed programming learning: application to postgraduate studies

Most students graduated in Marine Science or other related disciplines (e.g. Geology, Biology, Chemistry) lack the basic background knowledge in scientific programming and modelling (e.g. Matlab, Fortran, Python), necessary in numerical disciplines such as Physical or Coastal Oceanography. Hence, when they enroll for postgraduate studies in Oceanography they are not able to properly follow the lessons related to the above disciplines and generally become discouraged. Trying to meet the needs of those students during the lessons would result in not accomplishing the course’s program, given the fact that MSc programs have concentrated material and are extremely demanding for the students. For this reason, a collaborative effort has been made among various lecturers to develop tutorials in order to promote self-directed learning among the MSc students with the aim of alleviating those deficiencies. These tutorials were applied in two different courses and consisted in: i) a quick-start Matlab guide for NetCDF meteorological and oceanographic data handling and plotting, and ii) the use of a front-end platform for visualising, analysing and evaluating results from the state-of-the-art morphodynamic model XBEACH-G. The above methods helped the students to understand the potential of programming and numerical modelling, as well as, the importance of applying such approaches both in consulting and research-based carriers. Overall, this methodology resulted in a higher level of satisfaction among students because it offered an active, flexible and self reliant learning method that was adapted to each person’s learning pace and difficulties. Finally, the tutorials proved to be an inclusive teaching strategy able to address the needs of students with different backgrounds, learning styles, and abilities, hence providing a more efficient learning environment, in which all students could reach their potential at their own pace and feel equally valued at the end of the course

Contribution of storms to shoreline changes in mesotidal dissipative beaches: case study in the Gulf of Cadiz (SW Spain)

In this study an analysis of storminess and rates of shoreline change is performed and discussed jointly in four geomorphological units of the Gulf of Cadiz (SW Spain) for the period of 1956-2010. For this purpose, storm events are identified based on the following characteristics: wave height above 2.5 m, a minimum duration of 12 h and events with calm periods of less than 24 h were considered as a single event. Subsequently, energy parameters are determined in order to characterize storm-induced impacts. Conversely, geographic information system (GIS) tools are used to measure shoreline changes in aerial photographs and orthophotographs of each site, selecting the high water line as shoreline proxy. Each geomorphological unit is divided into different behavioural patterns according to recorded coastal changes, so that each one shows a particular behaviour.In general the variability of shoreline changes that is explained by storms and the relation between storm parameters and coastal changes present better results in exposed areas (Cadiz and Vistahermosa) than in sheltered areas (Valdelagrana spit barrier) because the former are more sensitive to storm impacts. On the contrary, in areas where there is no relation between coastal changes and storm parameters (Valdelagrana and Sancti Petri sand spit), it is suggested that anthropogenic factors are the main forcing agents determining shoreline behaviour. However, in these areas the storminess also modulates coastline recession by increasing erosion when the number of storms is high

The Influence of Camera Calibration on Nearshore Bathymetry Estimation from UAV Videos

Measuring the nearshore bathymetry is critical in coastal management and morphodynamic studies. The recent advent of Unmanned Aerial Vehicles (UAVs), in combination with coastal video monitoring techniques, allows for an alternative and low cost evaluation of the nearshore bathymetry. Camera calibration and stabilization is a critical issue in bathymetry estimation from video systems. This work introduces a new methodology in order to obtain such bathymetries, and it compares the results to echo-sounder ground truth data. The goal is to gain a better understanding on the influence of the camera calibration and stabilization on the inferred bathymetry. The results show how the proposed methodology allows for accurate evaluations of the bathymetry, with overall root mean square errors in the order of 40 cm. It is shown that the intrinsic calibration of the camera, related to the lens distortion, is the most critical aspect. Here, the intrinsic calibration that was obtained directly during the flight yields the best results

Desarrollo de tutoriales para promover el auto-aprendizaje entre estudiantes de postgrado

Gran parte de los graduados en Ciencias del Mar o disciplinas similares carecen de una formación básica en programación científica y modelización numérica. Como consecuencia, cuando acceden a ciertos estudios de postgrado, encuentran grandes dificultades para seguir los contenidos de muchas asignaturas. Otra consecuencia directa de esta falta de formación es que, el profesor se ve obligado a reducir el programa de la asignatura. Varios profesores han llevado a cabo un esfuerzo cooperativo para promover el auto-aprendizaje de los alumnos. Se desarrollaron tutoriales centrados en dos asignaturas del Máster de Oceanografía que consistieron en: (i) una guía para la lectura, tratamiento y representación gráfica de datos oceanográficos y meteorológicos con Matlab y (ii) una aplicación interactiva para visualizar, evaluar y analizarlos resultados del modelo morfodinámico XBEACH-G. En general, esta metodología incrementó el nivel de satisfacción de los estudiantes con las asignaturas implicadas, ya que les proporcionó un método de aprendizaje activo, flexible y autónomo. Además, este aumento en la motivación les permitió entender el gran potencial de la programación científica y los modelos numéricos y su relevancia tanto para la investigación académica como para el sector empresarial. El uso de los tutoriales demostró ser una estrategia de educación inclusiva capaz de atender las necesidades de estudiantes con diferentes grados de formación, aptitud y capacidad de aprendizaje, generando por lo tanto un ambiente de aprendizaje más eficiente en el que todos los estudiantes, protagonistas del proceso de enseñanza-aprendizaje, pudieron desarrollar su máximo potencial de manera progresiva a su propio ritmo. Por último, el trabajo cooperativo entre el profesorado, que se ha convertido a día de hoy en una nota distintiva del sistema educativo actual, permitió el intercambio de ideas y materiales. En un futuro, se espera continuar con esta filosofía y desarrollar nuevas estrategias bajo el enfoque constructivista