Development of a methodology to obtain climate change projections of coastline evolution considering multiple time and spatial scales in an uncertainty context

RESUMEN: En esta tesis doctoral se establece un marco para el análisis de impactos costeros compatible con los condicionantes computacionales y de escala impuestos por el cambio climático y orientado hacia una mejor estimación del riesgo y hacia el diseño de estrategias de adaptación efectivas. Para ello, se desarrolla un modelo de evolución de la línea de costa basado en la física de los procesos y enriquecido por datos mediante asimilación. Una vez validado, el modelo se usa para pronosticar la respuesta de un tramo costero considerando la incertidumbre asociada al oleaje y al nivel del mar futuros. Esas proyecciones de la línea de costa se emplean a su vez para actualizar la morfología costera y obtener proyecciones de inundación que incorporan el efecto de la erosión. Finalmente, se desarrolla un nuevo modelo capaz de resolver de forma acoplada la evolución de la línea de costa y la morfología costera aplicable a diferentes configuraciones incluidas playas con corales, vegetación y estructuras antrópicas.ABSTRACT: In this PhD thesis, a coastal impact modelling framework that fulfills the computational and scale constraints imposed by climate change and oriented to produce better risk estimates and designing effective adaptation strategies, is established. To this end, a novel physics-based and data-assimilated shoreline evolution model is built. Once validated, the model is used to forecast the shoreline response considering climate-related uncertainty associated to future waves and water levels. Next, the shoreline projections are employed to update the nearshore morphology and to obtain erosion-enhanced flooding projections. Finally, a novel model capable of jointly resolving the shoreline evolution and the complete coastal morphology applicable to most of the sandy coastal settings worldwide including beaches protected by coral reefs, vegetation or man-made structures; is developed

Modelado numérico de la interacción vehículo-estructura y aplicación al estudio de puentes atirantados frente al tráfico vehicular

RESUMEN: el presente estudio porta sobre el problema de interacción vehículo-estructura, ión de las propiedades dinámicas de los dos subsistemas (estructura y vehículos) por los efectos recíprocos entre ambos. Convencionalmente, la investigación aplicada al proyecto de estructuras se centraba en la determinación del factor de impacto, definido como el porcentaje de mayoración de la respuesta estática de la estructura al considerar los efectos inerciales y viscosos que se generan. Generalmente, el efecto del tráfico vehicular se modeliza mediante cargas móviles, por lo que no se tiene en cuenta la interacción. Este tipo de análisis resulta válido para analizar la respuesta de gran parte de los puentes convencionales, aunque no aporta ninguna información sobre la dinámica vehicular ni sobre el confort de tránsito del pasajero. En el caso de que el confort de tránsito sea un parámetro crítico de diseño o en el proyecto de estructuras en las que la masa de la sobrecarga de tráfico sea significativa frente al peso propio del tablero, se hace indispensable la modelización de la interacción vehículo-estructura. La complejidad de las ecuaciones acopladas de los dos subsistemas (vehículo y estructura) obliga al recurso a métodos numéricos. Por ello, se ha desarrollado un programa de elementos finitos en el plano que permite, entre otros, resolver problemas de interacción vehículo-estructura considerando la presencia de un pavimento rugoso. El programa es ampliamente validado mediante soluciones analíticas y semi-analíticas presentes en la literatura para casos simples y mediante el programa Sofistik en estructuras más complejas. Posteriormente se aplica al estudio de puentes atirantados mediante un análisis paramétrico en el que se hace variar la masa y el espaciamiento de los vehículos, la rugosidad del firme, la inercia del tablero, la vinculación pila-tablero y la configuración del sistema de atirantamiento. La respuesta de los global del siste- ma vehículo-estructura es evaluada mediante factores de impacto de esfuerzos y desplazamientos y mediante el nivel de confort de tránsito obt a partir dela serie temporal de aceleraciones en la cabina de los vehículos.Máster en Ingeniería de Caminos, Canales y Puerto

Neglecting the effect of long- and short-term erosion can lead to spurious coastal flood risk projections and maladaptation

ABSTRACT: Flooding and erosion are among the most relevant hazards for coastal regions and although they are linked, their inherent complexity has typically led them to be addressed separately, potentially leading to highly uncertain estimates. This paper has three aims: (a) to present a methodology for coupling coastal flood projections with shoreline changes; (b) to quantify the effects of neglecting the coupling of flooding and erosion on future projections at a case study location; and (c) to analyse the relative importance of the climate-related uncertainty sources. We use a suite of statistical, process-based, and physics-based models to generate and downscale storms, compute water levels affected by storm morphodynamics and long-term profile changes and propagate flooding over topo-bathymetries that are in turn modified to incorporate the impact of sea-level rise, longshore sediment transport and storm-driven erosion. We sample climate uncertainty by considering storm variability (synthetic generation) and ensembles of radiative forcing scenarios, regional climate models, and sea-level rise trajectories. For illustration purposes, we consider a 40-km coastal stretch in the Spanish Mediterranean. We find that if the effect of erosion is neglected, the mean values of the total water level and flooded area can be either over- or underestimated by up to 18% and 22%, and up to 7% and 85%, respectively, with respect to our coupled results. The factors that most influence total water levels are storm erosion and profile geometry, highlighting the relevance of using real profiles in shoreface translation. In the flooded area, longshore transport can play a fundamental enhancing role. We also find that the coupling approach used can contribute more to the projection of flooded areas than the choice of climate models and sea-level rise trajectories even by 2100 (up to 76% versus 8% and 16%, respectively). We conclude that neglecting erosion effects on coastal flooding can have management implications, especially for urban beaches, leading to poor adaptation planning and maladaptation.This study was partially funded by the Spanish Government through the grant COASTALfutures (PID2021-126506OB-100); the Government of Cantabria through the FENIX Project; and the European Union’s Horizon 2020 CoCliCo Project (grant agreement No 101003598). AT and MA-C are also funded by the Spanish Ministry of Science and Innovation through the Ramon y Cajal Programme (RYC2021-030873-I) and the FPI studentship (PRE-2018-085009), respectively

Visualising the Uncertainty Cascade in Multi-Ensemble Probabilistic Coastal Erosion Projections

ABSTRACT:Future projections of coastal erosion, which are one of the most demanded climate services in coastal areas, are mainly developed using top-down approaches. These approaches consist of undertaking a sequence of steps that include selecting emission or concentration scenarios and climate models, correcting models bias, applying downscaling methods, and implementing coastal erosion models. The information involved in this modelling chain cascades across steps, and so does related uncertainty, which accumulates in the results. Here, we develop long-term multi-ensemble probabilistic coastal erosion projections following the steps of the top-down approach, factorise, decompose and visualise the uncertainty cascade using real data and analyse the contribution of the uncertainty sources (knowledge-based and intrinsic) to the total uncertainty. We find a multi-modal response in long-term erosion estimates and demonstrate that not sampling internal climate variability?s uncertainty sufficiently could lead to a truncated outcomes range, affecting decision-making. Additionally, the noise arising from internal variability (rare outcomes) appears to be an important part of the full range of results, as it turns out that the most extreme shoreline retreat events occur for the simulated chronologies of climate forcing conditions. We conclude that, to capture the full uncertainty, all sources need to be properly sampled considering the climate-related forcing variables involved, the degree of anthropogenic impact and time horizon targeted.AT acknowledges the financial support from the FENIX Project by the Government of Cantabria. This research was also funded by the Spanish Government via the grant RISKCOADAPT (BIA2017-89401-R)

Deep uncertainties in shoreline change projections: an extra-probabilistic approach applied to sandy beaches

ABSTRACT:Global mean sea level rise and its acceleration are projected to aggravate coastal erosion over the 21st century, which constitutes a major challenge for coastal adaptation. Projections of shoreline retreat are highly uncertain, however, namely due to deeply uncertain mean sea level projections and the absence of consensus on a coastal impact model. An improved understanding and a better quantification of these sources of deep uncertainty are hence required to improve coastal risk management and inform adaptation decisions. In this work we present and apply a new extraprobabilistic framework to develop shoreline change projections of sandy coasts that allows consideration of intrinsic (or aleatory) and knowledge-based (or epistemic) uncertainties exhaustively and transparently. This framework builds upon an empirical shoreline change model to which we ascribe possibility functions to represent deeply uncertain variables. The model is applied to two local sites in Aquitaine (France) and Castellón (Spain). First, we validate the framework against historical shoreline observations and then develop shoreline change projections that account for possible (although unlikely) low-end and high-end mean sea level scenarios. Our high-end projections show for instance that shoreline retreats of up to 200m in Aquitaine and 130m in Castellón are plausible by 2100, while low-end projections revealed that 58 and 37m modest shoreline retreats, respectively, are also plausible. Such extended intervals of possible future shoreline changes reflect an ambiguity in the probabilistic description of shoreline change projections, which could be substantially reduced by better constraining sea level rise (SLR) projections and improving coastal impact models. We found for instance that if mean sea level by 2100 does not exceed 1m, the ambiguity can be reduced by more than 50%. This could be achieved through an ambitious climate mitigation policy and improved knowledge on ice sheets.This research has been supported by the BRGM, IHCantabria and the ERA4CS-ECLISEA project (grant no. 690462)

Hydrodynamic analysis of the Sardinero and Puntal-Somo-Loredo beaches with XBeach

RESUMEN: Se realiza un análisis hidrodinámico utilizando el módulo de propagación del modelo numérico XBeach en las playas del Sardinero y Puntal-Somo-Loredo. El objeto de este estudio es modelar físicamente procesos de inundación costera aprovechando la capacidad que tiene el citado programa para generar la onda infragravitatoria asociada al grupo de olas. En la mayoría de los casos, cuando se estudia inundación costera, la parte de determinación de los niveles de run-up y surfbeat se lleva a cabo mediante fórmulas empíricas basadas en observaciones en playas. El fin de este estudio es modelar el surfbeat, generado por las ondas infragravitatorias, y su variabilidad espacial. En el primer capítulo analizamos la motivación de este estudio, la ubicación de las playas, el objetivo y la estructura del TFG. Posteriormente se exponen los procesos fundamentales que contribuyen a la inundación costera así como el estado del arte de su parametrización. En el capítulo 3, se describe el modelo XBeach así como el análisis de sensibilidad de la resolución del grid computacional. En el capítulo 4 se realizan varias simulaciones alterando distintos parámetros físicos para ver la respuesta de XBeach. Después de comprender el modelo, en el capítulo 5 estudi- amos la inundación ocurrida en el temporal de Marzo del 2014, gracias a mapas en 2-D, perfiles transversales, series temporales en puntos clave y sensores de run-up. Finalmente ejecutamos XBeach en el modo no hidrostático, para realizar un análisis espectral, primero puntual y luego espacial, en busca de concentraciones de energía de onda larga y periodos resonates en la zona de estudio. De esta investigación se extraen dos conclusiones principalmente. Por un lado, si queremos estudiar en detalle la inundación, las fórmulas empíricas de surfbeat y run-up no describen con detalle la variabilidad espacial ni la vulnerabilidad de zonas concretas, por lo que es de necesidad el empleo de modelos numéricos tipo XBeach. Por otro lado, del estudio espectral hemos obtenido el modo de oscilación natural de onda infragravitatoria en el sistema Sardinero y Puntal - Somo - Loredo en rangos de periodos de 270 s < T < 320 s y 340 s < T < 430 s.ABSTRACT: We have performed a hydrodynamic analysis using the XBeach propagation module in the Sardinero and Puntal-Somo-Loredo beaches. The objective of this research is to physically model coastal flooding taking the advantage of the XBeach capabil- ity of generating the infragravity wave associated to wave groups. When studying coastal flooding, the determination of run-up and surfbeat levels is mainly done by empirical formulations from beach surveys. The aim of this study is to model surf- beat, generated by infragravity waves, and its spatial variability. In the first chapter we have analyzed the motivation of this research, the location of the study area, the objective and the structure of the document. Later, the different fundamental processes that trigger coastal flooding are exposed, as well as the state of the art of their parametrization. In chapter 3, we have described the XBeach model and the computational grid resolution adopted from the sensitivity analysis. In chapter 4, several XBeach simulations in which we have altered several physical parameters are analyzed with the purpose of studying the behavior of the model. In chapter 5 we have studied the flooding event that happened during the 2014 storm in March by looking at 2-D plots, transverse profiles, temporal series and run-up gauges. Finally XBeach was executed in the non hydrostatic mode, in order to per- form an spectral analysis, first at key points and then in the 2-D domain, in order to look for long wave energy concentrations and resonant periods in the study area. From this investigation we can extract two conclusions. On one hand, if we want to study flooding in detail, the empirical surfbeat and run-up formulations do not describe properly the spatial variability nor the vulnerability of particular zones, that is why we need to employ numerical models such as XBeach. On the other hand, from the spectral analysis we have obtained the natural oscillation mode of infragravity waves in the system Sardinero and Puntal - Somo - Loredo in periods of 270 s < T < 320 s y 340 s < T < 430 s.Grado en Ingeniería civi

Extreme morphodynamic analysis of the Sardinero and Puntal-Somo-Loredo beaches with XBeach

RESUMEN: Se realiza un análisis morfodinámico partiendo del modelo numérico de erosión extremal en playas XBeach, una vez se ha comprendido su comportamiento en el estudio de la hidrodinámica, en las playas del Sardinero y Puntal - Somo - Loredo. El objeto de este estudio es el modelado de los procesos de erosión costera y su calibrado gracias a la ayuda de la campaña de medida realizada antes y después del temporal del 2016. Una vez calibrado el modelo se mostrará su utilidad mediante un caso práctico, el diseño de la regeneración de la duna Loredo. En el primer capítulo, analizamos la motivación de este estudio, la ubicación de las playas, el objetivo y la estructura del TFG. Posteriormente se exponen brevemente los procesos que desencadenan la erosión costera, se estudian los componentes del nivel del mar, la morfodinámica de playas y el estado del arte del modelado numérico de la evolución costera. En el capítulo 3, se describe el modelo XBeach y se incluye un análisis de la sensibilidad del grid computacional. En el capítulo 4 se lleva a cabo la calibración del modelo gracias a la campaña de campo realizada antes y después del temporal del 2016. Una vez calibrado el modelo, en el capítulo 5 lo aplicamos en el estudio probabilístico de la erosión en la duna de Loredo. Para ello se simulan varios temporales asociados a diferentes periodos de retorno obteniendo la relación entre volumen erosionado y periodo de retorno en años. En el capítulo 6 y para concluir el TFG de la mención de Construcción se diseña la duna de Loredo siguiendo la ROM, para así obtener un periodo de retorno de diseño y por lo tanto un volumen de erosión. Con ese dato se estudia el proceso de regeneración y revegetación dunar, que alcanza un presupuesto base de licitación de 640.338,13 euros. Como conclusiones podemos extraer que el modelado morfodinámico extremal a corto plazo es todavía un campo en desarrollo cuyos algoritmos son extremadamente complejos y computacionalmente exigentes, que requieren calibración para la obtención de resultados. Sin embargo, una vez afinados, sus campos de aplicación y utilidad son muy amplios en ingeniería de costas y puertos.ABSTRACT: We have performed a morphodynamic analysis using the extreme beach erosion model XBeach, once we understood its response in the hydrodynamic study, in the Sardinero and Puntal - Somo - Loredo beaches. The aim of this research is to model coastal erosion and its calibration procedure thank to the field measurements carried out before and after the 2016 storm in the Somo - Loredo area. Once the model is calibrated, one practical application is shown, the nourishment design of the Loredo dune. In the first chapter, we analyzed the motivation of this research, the location of the beaches, the objective and the structure of the end of degree final thesis. In the next chapter, we briefly described the different processes that trigger coastal erosion, we studied the different sea level components, beach morphodynamics and the state of the art of the beach evolution numerical modelling. In chapter 3, the XBeach model is described and the grid resolution sensitivity analysis is also included. In chapter 4 we carried out the model calibration thank to the data from the survey we did before and after the 2016 storm. Once the model is calibrated, in chapter 5 we applied it in the probabilistic study of erosion in the Loredo dune. To achieve that, we have simulated several storms associated to several return periods obtaining the relationship between the return period in years and the associated dune eroded volume. In chapter 6 and to conclude the construction end of degree final thesis we designed the Loredo dune following the ROM, to obtain the design return period and therefore an erosion volume. With this data we studied the nourishment and revegetation procedure that yields a based tender budget of 640.338,13 euros. As conclusions we can extract that short term extreme morphodynamic modelling is still a developing field whose algorithms are extremely complex and very expensive computationally, that require calibration to yield reasonable results. However, once the model is trimmed, their fields of application are really wide in coastal and port engineeringGrado en Ingeniería civi

A nearshore evolution model for sandy coasts: IH-LANSloc

This paper presents IH-LANSloc (IH-Long-term Anthropized coastlines Simulation tool for local-scale studies), a numerical model that solves shoreline and nearshore evolution at short and long-term time scales and in a wide variety of sandy coastal settings. IH-LANSloc results from the two-way fully coupling of a data-assimilated shoreline evolution model with a process-based wave propagation model and a rules-based profile translation tool. In contrast to shoreline evolution models, IH-LANSloc is able to reproduce the nearshore evolution in areas with complex bathymetries, considering the effects of human interventions (e.g., groynes, seawalls, breakwaters and nourishments) and natural ecosystems (e.g., coral reefs, seagrasses, and vegetation patches). This nearshore evolution model is less computationally expensive and is applicable to larger time scales than most process-based models and provides more accurate and richer results than present-day physics-based models. Model validation is carried out at an embayed beach in northern Spain showing great agreement with satellite-derived shoreline observations (RMSE<7m).MA-C acknowledges the financial support from the Ministerio de Ciencia e Innovaci´on and Innovation through the FPI studentship (PRE, 2018–085009). This research was partially supported by the Ministerio de Ciencia e Innovaci´on through the grants COASTALfutures (PID2021- 126506OB-100; MCIN/AEI/10.13039/501100011033/FEDER UE), CoastDiTwin (TED2021-131885B-100; MCIN/AEI and NextGenerationEU/ PRTR) and the ThinkInAzul programme (with funding from European Union NextGenerationEU/PRTR-C17.I1 and the Comunidad de Cantabria) and by the Comunidad de Cantabria through the FENIX Project (GFLOOD). AT is also funded by the Ramon y Cajal Programme (RYC2021-030873-I) of the Ministerio de Ciencia e Innovaci´on (MCIN/ AEI and NextGenerationEU/PRTR)

Demonstrating the value of beaches for adaptation to future coastal flood risk

Cost-effective coastal flood adaptation requires a realistic valuation of losses, costs and benefits considering the uncertainty of future flood projections and limited resources for adaptation. Here we present an approach to quantify the flood protection benefits of beaches accounting for the dynamic interaction of storm erosion, long-term shoreline evolution and flooding. We apply the method in Narrabeen-Collaroy (Australia) considering uncertainty in different shared socioeconomic pathways, sea-level rise projections, and beach conditions. By 2100, results show that failing to consider erosion can underestimate flood damage by a factor of 2 and maintaining present-day beach width can avoid 785 million AUD worth assets from flood damage. By 2050, the flood protection and recreational benefits of holding the current mean shoreline could bemore than 150 times the cost of nourishment. Our results give insight on the benefits of beaches for adaptation and can help accelerate financial instruments for restoration.A.T. acknowledges financial support from the Ministerio de Ciencia e Innovación (MCIN/AEI and NextGenerationEU/PRTR) through the Ramon y Cajal Programme (RYC2021-030873-I). This research was also funded by the Ministerio de Ciencia e Innovación through the grant COASTALfutures (PID2021-126506OB-100 with funding from MCIN/AEI/ 10.13039/501100011033/FEDER UE) and the ThinkInAzul Programme (with funding from European Union NextGenerationEU/PRTR-C17.I1 and the Comunidad de Cantabria) to A.T. and I.J.L.; the Comunidad de Cantabria through the FENIX Project to A.T.; and the European Union through the Horizon 2020 CoCliCo Project (grant agreement No 101003598) to A.T., I.J.L. and G.L