No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Riscos de Exposiç ão de Frentes Urbanas Para Diferentes Intervenções de Defesa Costeira
... This involves the development of a method integrating the effects of both cross-shore and longshoresediment-transport processes into the system evolution. Following the recommendation presented by Hanson et al. [17], the method integrates both components of sediment transport by combining the results provided by two existing simplified numerical models: LTC [34] that simulates longshore-sediment-transport processes, and CS-Model [25], to obtain the cross-shore sediment transport within the beach profiles. To achieve the main objective defined for the study, the research comprised two primary phases: (1) the development of a method to integrate cross-shore and longshore processes of sediment transport; ...
... To achieve the proposed goal, a model was developed that longshore and cross-shore-sediment-transport processes associated with dune erosion caused by wave impact. To achieve the proposed goal, a model was developed that integrates the results of two existing numerical models, LTC [34] and CS-Model [25], which simulate medium-to-long-term longshore and cross-shore-sediment-transport processes, respectively. This section begins with the presentation of the main assumptions of the two models that are the basis for the study. ...
... LTC (Long-Term Configuration) is a shoreline evolution numerical model designed for sandy beaches [34]. Figure 1 presents the main features of the model, which considers a numerical domain defining the bathymetry and topography of the coastal system through a grid of points (NX-number of points alongshore and NY-number of points across-shore). ...
Beach–dune systems are highly dynamic features of the coastal system, the evolution of which is influenced by several processes that occur at very different spatial and temporal scales. To mitigate shoreline retreat that threatens extensive coastal areas worldwide, coastal erosion mitigation measures are implemented, aiming to make coastal areas resilient to the effects induced by coastal erosion and the anticipated climate change related to storms, flood events and sea level rise. Numerical modelling can support planned and sustainable coastal management from a medium-to-long-term perspective (decades). This research focuses on presenting contributions regarding the numerical modelling of subaerial beach dynamics (berm width and dune systems interactions) from a medium-term perspective. The method applied is based on a combination of the results of two simplified numerical models (the LTC and CS-Model). The results demonstrate the potential of the proposed combined model for medium-term projections, allowing for the interpretation of beach–dune dynamics and the evaluation of the importance of longshore and cross-shore sediment transport processes.
... The AX-COAST project aims to develop new capacities in modeling cross-shore sediment transport processes using a cost-benefit assessment tool, COAST [3]. The COAST tool has three main modules: a shoreline evolution numerical model (Long-Term Configuration model-LTC [4,5]), a coastal intervention pre-design module (XD-COAST [6,7]) and a cost-benefit analysis module. ...
... It considers processes related to dune erosion, overwash, sediment transport by wind and exchange of sedimentary material between the bar and the berm [9,16]. The LTC model is based on the one-line theory and simulates medium-to long-term shoreline evolution considering natural and anthropogenic scenarios [4]. Other shoreline evolution models include GENESIS [17,18], Delft3D [19,20], Cascade [21,22], ONELINE [23] and the General Shoreline beach model [24,25]. ...
... Other shoreline evolution models include GENESIS [17,18], Delft3D [19,20], Cascade [21,22], ONELINE [23] and the General Shoreline beach model [24,25]. The LTC model was developed by Coelho [4] and allows for the development of adaptations to include the combination of cross-shore and shoreline evolution capabilities. Integration of the two numerical models will help to better represent artificial nourishment behavior in the COAST tool. ...
Numerical models can be powerful tools for evaluating the best scenarios for the construction of artificial nourishments to mitigate coastal erosion. Until recent decades, when looking at medium- to long-term simulations, cross-shore and alongshore processes have been studied separately. Accounting for both processes in a shoreline evolution numerical model would improve the understanding and predictive capacity of future changes in coastline evolution. The AX-COAST project aims to develop new capacities in modeling cross-shore sediment transport processes by adding the CS-Model, a cross-shore numerical model, into the existing LTC (Long-Term Configuration) model. The LTC model is a shoreline evolution numerical model which is a module of the cost–benefit assessment tool COAST. This work presents the first steps of the CS-Model implementation, which involve evaluating its performance by calibrating the model with extensive measured datasets of wave climate, beach profiles, tide levels, etc., from coastal areas in IJmuiden and Sand Motor in the Netherlands. The results show good agreement between modeled and observed values. Additionally, wave climate datasets derived from global and regional wave models were considered to evaluate modeling performance at IJmuiden. Using derived timeseries from the wave models did not significantly lead to different results compared to using measured data. The obtained mean absolute and relative errors for each profile were low for both types of datasets. Calibration processes with consistent data are important in modeling simulations to accurately represent the study area and ensure the credibility of future simulations.
... Apresenta-se também a caracterização física da área de estudo, incluindo a definição dos agentes forçadores (a agitação marítima) e a caracterização das taxas de transporte sedimentar. Para a simulação da posição da linha de costa, optou-se por utilizar o modelo numérico LTC (Coelho, 2005), devido à sua capacidade de reproduzir e projetar a linha de costa a médio-longo prazo, com base na equação de continuidade aplicada ao transporte sedimentar. ...
... Foram preparados 4 domínios de cálculo (malhas), tendo como referência a localização das fronteiras identificadas. As malhas são compostas por uma grelha regular de pontos espaçados de 20 m no eixo X (direção Este-Oeste) e 40 m no eixo Y (direção Norte-Sul), e estendem-se sensivelmente entre as cotas -25 m e +25 m (ZH), conforme indicado na Tabela 1. (Coelho, 2005). Geralmente, para praias intermédias (características da generalidade da costa oeste portuguesa), as propostas variam entre m=1/2, m=4/7 e m=2/3, valor este que se generalizou e que foi adotado. ...
... O modelo LTC, Long-term Configuration (Coelho, 2005), permite fazer projeções da posição da linha de costa em zonas costeiras arenosas e admite o estabelecimento de cenários naturais e antropogénicos, sendo baseado nos pressupostos dos modelos de '1-linha'. Para efeitos de calibração do modelo LTC, foram simulados os últimos 50 anos completos da série hindcast produzida pelo modelo WAVEWATCH III Os resultados da calibração atenderam prioritariamente às taxas de variação da posição da linha de costa em prejuízo das taxas de transporte sedimentar, devido à dificuldade de considerar simultaneamente a representação adequada destes dois parâmetros. ...
Nas últimas décadas a extensa faixa do litoral continental português tem verificado um crescimento significativo na pressão exercida sobre o ambiente costeiro, associada à diminuição da contribuição sedimentar, acompanhada da ocorrência de eventos com elevada energia e a consequente tendência regressiva da posição da linha da costa. Neste contexto, decidiu-se aplicar o modelo numérico LTC, Long-term Configuration (Coelho, 2005) a três áreas costeiras em risco de erosão, para avaliar o comportamento da linha de costa, em projeções a 20 anos. Os três locais de estudo localizam-se na costa continental oeste, correspondendo aos trechos: São Jacinto-Gafanha da Boa Hora; Cabo Mondego-Leirosa; Cova do Vapor-Fonte da Telha. Os resultados permitiram identificar uma tendência regressiva da posição da linha de costa nos três trechos, com exceção na praia da Claridade (Figueira da Foz), onde se verifica uma tendência de acreção. É na região costeira compreendida entre a Costa Nova e a Vagueira que se verifica a projeção da maior taxa média de recuo da posição da linha de costa: 9.08 m/ano, associada a uma perda de 4.2x10^5 m2 de território.
... Estas obras podem ser construídas em: estruturas de concreto, de asfalto, de geossintéticos, paredes de estacas-prancha ou enrocamento; objetivam a redução da ação das ondas e, no caso dos blocos de enrocamento, atuam por meio da absorção da energia nas faces e espaços vazios (COELHO, 2005). O material é colocado ao longo da face de uma praia, de encostas ou dunas, e a estrutura apresenta três componentes principais: a camada de armadura estável (manto resistente), a camada de filtro, ou underlayer, e o pé de talude, fundação que oferece estabilidade à estrutura (FERNANDES, 2017). ...
... Os espigões são frequentemente utilizados em conjunto com outras obras; as mais comuns são as obras longitudinais aderentes e as de alimentação artificial de areia. Tratam-se de intervenções mistas, adotadas em zonas muito críticas ou com o intuito de reduzir os impactos negativos e minorar custos associados a cada intervenção de forma isolada (COELHO, 2005). ...
... Dessa forma, funcionam como obstáculo ao vento, de modo a reter a areia no pós-praia como estoque sedimentar para reposição. Coelho (2005) expõe que uma duna artificial com um núcleo estrutural em enrocamento ou em blocos de concreto pode funcionar como uma barreira ou como um revestimento longitudinal. ...
Dada a importância na economia local que as zonas costeiras representam, é
fundamental a manutenção dos ambientes costeiros para assegurar seu pleno funcionamento. A Praia do Meio, região de estudo localizada no município de Natal/RN, sofre do fenômeno de erosão costeira. Ainda que obras de reestruturação tenham sido concluídas em 2014, incidentes de desabamento já ocorreram e a infraestrutura da orla encontra-se ameaçada pelo avanço do mar; assim, a solução de proteção costeira adotada foi o enrocamento aderente. O presente trabalho tem
como objetivo a avaliação do método adotado na Praia do Meio, comparado a outras alternativas de proteção da Engenharia Costeira. A escolha do enrocamento foi coerente com o caráter emergencial da obra e com as condições do local, porém a adoção de outras soluções definitivas faz-se necessária.
... The aim of this study is to evaluate the behavior of the shoreline evolution in three coastal stretches from mainland Portugal, selected due to their long-lasting erosional tendencies: Aveiro, Figueira da Foz and, Caparica coast. The Long-Term Configuration (LTC) numerical model was used (Coelho 2005), based on its capacity to project and reproduce the coastline position in a mid-long term, through the application of the equation of continuity to sediment transport (Coelho 2005;Pombo et al. 2022). The shoreline behavior was analyzed through a 20-year projection. ...
... The aim of this study is to evaluate the behavior of the shoreline evolution in three coastal stretches from mainland Portugal, selected due to their long-lasting erosional tendencies: Aveiro, Figueira da Foz and, Caparica coast. The Long-Term Configuration (LTC) numerical model was used (Coelho 2005), based on its capacity to project and reproduce the coastline position in a mid-long term, through the application of the equation of continuity to sediment transport (Coelho 2005;Pombo et al. 2022). The shoreline behavior was analyzed through a 20-year projection. ...
... A 1-line numerical model, LTC (Coelho 2005;Coelho et al. 2007;Silva et al. 2007;Coelho et al. 2013;Lima and Coelho 2017), was applied in the present study. The LTC allows to project the shoreline position in sandy coasts and enables the establishment of natural and anthropogenic scenarios. ...
With climate change being addressed as a concern that poses a risk to the coastal communities, alongside with warnings of mean sea-level rise (SLR), the present study aims to highlight the influence of these two factors in the projection of the coastline position, in a time-frame of 20 years. The shoreline evolution of three littoral stretches from the western Portuguese coast (Aveiro, Figueira da Foz and Caparica coast) was analyzed, due to their vulnerability to persistent erosion processes. Coastline projections were simulated with the Long-Term Configuration (LTC) numerical model, calibrated by considering the past shoreline rate-of-change (1958–2010). The behavior of the coastline projection was studied by simulating six different forcing scenarios. Firstly, the coastline was subjected to three different wave climates to depict the effect of climate change: a historical wave climate (1989–2008); and two near future wave climates (2026–2045), assuming the Representative Concentration Pathway (RCP) RCP4.5 and RCP8.5. Secondly, the coastline was projected to simulate an annual increase in the sea water level of 0.75 cm for the three wave climates, isolating the influence of SLR. Considering the shoreline position over time, annual areas of erosion and accretion were measured for the six scenarios. Climate change wave scenarios showed a decrease in waves incoming from the NW quadrant and, an increase from the N and W quadrants when compared with historical data. The global shoreline tendencies where maintained on each study site, but the climate change scenarios influence showed different behavior of the coastline along the Portuguese littoral.
... This is based on a participatory process in which adaptation pathways for climate change adaptation were defined. To achieve this, the Long-Term Configuration (LTC) model, a coastline evolution model, was employed (Coelho, 2005;Coelho et al., 2013;Guimarães et al., 2016;Lima andCoelho, 2017, 2019) in combination with a cost-benefit analysis, using the COAST tool Lima, 2018;Lima et al., 2020), and local ecosystem service values (ESV) estimates, using meta-analytic function transfer (Magalhães Filho et al., 2021. This study builds upon previous research conducted by Coelho et al., 2020Coelho et al., , 2022Lima et al., 2020;Magalhães Filho et al., 2021 It introduces a participatory process for defining scenarios and incorporates an assessment of the costs and benefits associated with artificial nourishment in relation to the coastal works maintenance and overtopping events. ...
... The methodology developed is based on three main phases ( Fig. 1): i) Participative Workshops Alves, 2021;Matos et al., 2022;Rato et al., 2021); ii) Shoreline evolution projection in a long-term horizon (applying LTC numerical model, Coelho, 2005); iii) Cost-Benefit Analysis to each intervention scenario (applying COAST tool, Lima, 2018). The methodology is described in the following sections. ...
... This study uses LTC -Long Term Configuration model (Coelho, 2005), that is a shoreline model for sandy beaches that integrates a basic classical one-line model with a rule-based model for the distribution of erosion and accretion volumes along the beach profile (Coelho et al., 2004(Coelho et al., , 2007. This model allows the user to simulate different coastal erosion protection and adaptation interventions, such as artificial sand nourishment, groins, revetments, point source alluvial and detached breakwaters. ...
The Ovar coastline, located on the western coast of Portugal, is renowned for being one of the most erosion-prone and vulnerable areas in the country. Addressing the significant challenges faced by local communities requires the development of modern coastal adaptation strategies that encompass social, environmental, and economic factors. In this study, a participatory approach was employed to establish Climate Change Adaptation Pathways for the period between 2020 and 2100. The majority of the scenarios examined prioritize artificial nourishments, which are increasingly being acknowledged as a vital solution for mitigating coastal erosion worldwide. However , the effectiveness and durability of these measures rely on various design parameters, including placement location, frequency, volume, initiation, and the presence or absence of coastal works, among others. This research presents the primary findings of 12 scenarios simulated using the Long-Term Configuration (LTC) model and cost-benefit analysis using the COAST tool in combination with local ecosystem service value estimates (using meta-analytic function transfer) to take into account environmental benefits. This analysis aims to assess the physical and economic performance of artificial nourishments by examining the efficacy of different scenarios in mitigating coastal erosion, ultimately supporting decision-making processes related to coastal planning and management. The results highlight the intricate factors involved in determining the optimal nourishment option, which depends on aspects such as site-specific conditions, land uses and ecosystems services, and the main objectives of the intervention.
... Este mesmo autor também indica que a cartografia de suscetibilidade deve ser resultado de, no mínimo, o efeito combinado de quatro componentes: a cota do nível médio do mar, a elevação da maré astronómica, a sobre-elevação meteorológica e o espraio da onda. Já em Coelho (2005) e Coelho et al. (2006) são identificadas nove componentes da vulnerabilidade: cobertura do solo, amplitude da maré, taxa de erosão/acreção, geomorfologia, altura máxima da onda, ações antropogénicas, cota topográfica, distância à linha de costa e geologia. Em Direção Regional de Ambiente (2019) O fator vulnerabilidade é constituído por oito componentes: ...
... A metodologia utilizada foi adaptada de Coelho (2005) De acordo com Borges et al. (2014), baseado num run up (espraio) modal de 7 m, a área de inundação é determinada por uma faixa de 100 m da costa em direção a terra, correspondendo à máxima penetração em terra de inundação costeira durante eventos extremos (Borges & Andrade, 1999). Como tal a componente distância à costa foi classificada em níveis de vulnerabilidade de acordo com relatório da Direção Regional A classificação desta componente baseou-se na classificação proposta por Coelho (2005), (Quadro 11). ...
... Alguns autores consideram como fatores da exposição às ações energéticas do mar a densidade populacional, a atividade económica, o património histórico e a ecologia (Coelho, 2005), (C. Pereira & Coelho, 2013 ...
Climate change is currently one of the factors that bring risks to the territory, these risks arise from causes such as rising sea levels, increased extreme weather events, and shortage of drinking water, among others. For the correct planning of the territory, it is necessary to quantify and locate these risks, taking the form of risk cartography. This is the only way to plan how to mitigate or prevent these risks. Within the risks caused by these factors, in the case of coastal areas and oceanic islands, the risk of coastal flooding is one of the most evident, as such it is necessary to quantify and locate this same risk in these areas. Therefore, this work aims to create a methodology for producing detailed cartography of coastal flood risk, quickly and systematically, using tools for spatial modeling and analysis, specifically the ModelBuilderTM tool from ESRI's ArcMapTM software and the AHP (Analytic Hierarchy Process) analysis method. As a case study for the implementation of this methodology it is used the island of Pico in the Azores Archipelago.
... Artificial nourishments present positive and negative aspects, with different impacts, costs, and benefits; therefore, this evaluation is dependent upon technical and local variables [5][6][7][8]. Thus, to mitigate coastal erosion based on artificial nourishments in a sustainable long-term perspective, it is necessary to maximize the benefits and reduce the costs of the intervention. ...
... In the first stage is applied a long-term shoreline evolution numerical model (LTC-longterm configuration [5]) to obtain the physical impacts of the nourishment scenarios. The coastal areas gained and/or not lost due to the intervention are evaluated along time to estimate the benefits. ...
... Within a specific study area, the software allows the user to define different monetary values for the territory alongshore. LTC [5] is a shoreline evolution numerical model for sandy beaches that combines a simple classical one-line model with a rule-based model for erosion/accretion volumes distribution along the beach profile [17,18]. The model was designed to support coastal management and planning, allowing one to obtain shoreline projections in a medium-to long-term perspective (decades), considering different coastal erosion mitigation measures without a high computational effort and without a complex calibration and validation process [18][19][20][21][22]. ...
Worldwide, artificial nourishments are being considered as one of the main coastal erosion mitigation measures. However, this solution is not permanent, since the natural removal of sediments that occurs after the sand deposition leads to the need of re-nourishment projects; thus, its performance and longevity dependent on several design parameters (placement site and extension alongshore, frequency, and volume, etc.) In this work, a methodological approach for cost–benefit assessment is applied to analyze the performance of artificial nourishments from a physical and economical point of view, by analyzing the effectiveness of different scenarios. The study was developed considering two study areas: a hypothetical situation (generic study area) and a real coastal stretch (Barra-Vagueira, located in the Portuguese west coast). The findings show the complexity in defining the best nourishment option, being dependent on the wave climate, site specific conditions, and main goal of the intervention. The proposed cost–benefit approach allows one to obtain and compare the physical and economic performance of artificial nourishments to mitigate coastal erosion, aiding the decision-making processes related to coastal planning and management.
... Graphical model of EPR4Q adapted for QGIS 3.14 since the original EPR4Q was created in QGIS 3.4. Transect creation section: dark green (1) are the inputs (shorelines and baselines); orange (2) is the transects creation process; calculation section: yellow (4) the application of the end point rate (EPR) equations, blue (3 and 5) is the one-side buffer creation, pink (6) is an unfinished extension; graphical result group: light green (7), gray (8) and salmon (9), and purple color (10) are the steps to the visualization of EPR forecast, and the red (11) (Coelho, 2005) and in the present work. The coastline retreat results (CRR) in both situations are calculated using a sea-level rise (SLR) of 0.50 m. ...
... In this study, the classic Bruun equation (Equation 1) was applied on Barra-Poço da Cruz coastal stretch (Aveiro region), using bathymetry and UAV photogrammetry DEM data ( Figure 1b). The results were compared with (Coelho, 2005)'s study, which performed a Bruun rule analysis in the same region. Profiles for the GEE Model (BRGM) were created with the values detailed in this study. ...
... Profiles for the GEE Model (BRGM) were created with the values detailed in this study. However, there are some bathymetric and topographic differences between the profiles performed by (Coelho, 2005) Bruun rule results and the previous study (Coelho, 2005) was performed. After the validation process, was tested for the area a scenario of sea-level rise of 1.21 m, considering the contribution of the Antarctic Ice Sheet (AIS) melting process (AIS= 60 cm) (Frederikse et al., 2020a). ...
Nowadays, the effects of sea-level rise can be observed in several countries of the world. The continuous rise of the mean sea-level in this century, reported by altimetry sensors and tide gauge data, and the constant increase of gas emissions, which implies the increase of global warming, will lead to global warming and more threatened areas in the future.
In Brazil, the main cities are located on the coast site, which means studies that apply mapping and new projections are crucial to identify hazardous areas and prevent the worst scenario in the future.
The present work consists in carrying out an analysis of the impact of sea-level rise for the end of this century in Rio Grande do Sul Coastal Plain (Southern Brazil), using three different Geographic Information Systems tools (GIS) created for this study.
The tools are a product of an extensive study about sea-level models and coastal barriers that include a topographic and bathymetric survey with Unmanned Aerial Vehicle (UAV), a systematic literature review and the digitization of cross-sections of the stratigraphic coastal barriers of Rio Grande do Sul. The study highlights the scientific production of the region, having collected all the stratigraphic surveys carried out until 2021 and discussed the rise in sea-level related to the formation of coastal barriers.
The first tool, named End Point Rate for QGIS (EPR4Q), performs trend analysis of the shoreline, and was validated using the well-known Digital Software Analysis System (DSAS) and Analysing Moving Boundaries Using R (AMBUR) software. The obtained results disclosed a high statistical correlation coefficient of 0.98 and 1.00 on linear, extensive and non-extensive shorelines, respectively. The second tool, called Uncertainty Bathtub Model (uBTM), calculates the probability of sea- level flooding by uncertainties in the projections and showed high correlation values of 0.75 to 1.00 with similar tools (Terrset Sea-level Impact, and Bathub Model). The third tool, Bruun Rule for GEE model (BRGM), applies the Bruun Rule in the GIS environment. Its validation showed a value of 0.97 of statistical correlation. The EPR4Q, uBTM and BRGM tools are open to the scientific community for improvement and to adapt the code for in-house applications and scientific research.
The results using EPR4Q in the coastal plain Rio Grande do Sul showed that about 28.60% of the coastline may retreat in 2100, being more severe in the southern areas.
In addition, the uBTM pointed to that 38.11 Km2 to 44.57 Km2 of urban area may be lost due to sea-level flood in 2100. The BRGM model showed a shoreline retreat ranging from -298.45 m to -1.7 Km that reflects the morphodynamical differences between
coastal sectors. The results underscore the importance of being warned about the impacts of sea-level rise in Rio Grande do Sul Coastal Plain to provide more evidence for politics and coastal managers so they can act in advance. Therefore, the study
carried out confirmed the hypothesis that it is possible to perform initial assessments of sea-level rise with the three tools created, since the study drives similar results (i.e. identification of erosive hotspots) as previously reported from other authors.
... Relativamente ao modelo LTC (Coelho, 2005), o mesmo, tal como o anterior, foi elaborado para praias arenosas e considera que o transporte sedimentar longitudinal e as condições de fronteira nos extremos da grelha modelada são as principais causas de alteração na zona costeira. Difere do LITMOD na representação da linha de costa, em que o LTC admite um ajuste do perfil ativo com as zonas adjacentes, pelo que a posição daquela linha depende também da batimetria e da topografia em cada perfil transversal. ...
... Esta ferramenta, desenvolvida no âmbito do trabalho de Lima (2018), tem a capacidade de avaliar a posição da linha de costa a médio-longo termo, e permitir a análise de cenários hipotéticos de intervenção na zona costeira, calculando o custo-benefício para cada cenário testado, por comparação com o cenário de não-intervenção. A ferramenta é composta por 3 módulos, que se integram entre si: módulo de evolução da linha de costa (Coelho, 2005;Lima, 2018); o módulo de pré-dimensionamento de obras de defesa costeira XD-COAST (Lima, 2011); e por último, o módulo de análise de custo-benefício. ...
... O método proposto utiliza o esquema de perfil transversal de praia representado pelo CS-Model (Figura 1), onde se podem incluir alimentações artificiais de sedimentos e os efeitos da subida do nível médio do mar (SLR). Os efeitos dos gradientes de transporte sólido longitudinal de sedimentos (SCR) são incluídos na evolução do perfil transversal de praia através das taxas de variação da posição da linha de costa fornecidas pelo modelo numérico de evolução da linha de costa LTC -Long Term Configuration (Coelho, 2005 ...
... (Housley, 1996). Atualmente, observações existentes a nível planetário mostram evoluções acentuadas nas zonas costeiras resultando em algumas locais numa perda significativa do território (Coelho, 2005). A nível da zona costeira continental do território português verifica-se o agravamento dos fenómenos de erosão que se repercutem numa situação generalizada de recuo da linha de costa (Veloso Gomes, 2007). ...
... Desta forma é fundamental sustentar as opções de mitigação dos problemas de erosão costeira. Como ferramenta de apoio à decisão e previsão pode-se recorrer à utilização de modelos numéricos, uma vez que, permitem modelar diversos cenários, comparando desempenhos e tornando-se uma técnica poderosa de apoio na avaliação de soluções (Coelho, 2005). Segundo , o movimento dos sedimentos ao longo da costa pode provocar erosão ou acreção, sendo que, a erosão provoca recessão da linha de costa (remoção de sedimentos) e a acreção provoca o avanço da posição da linha de costa em direção ao mar (adição de sedimentos). ...
... Os modelos numéricos de evolução da linha de costa são uma generalização dos modelos analíticos, simulando a evolução da linha de costa para diferentes configurações de praia, podendo incluir diversos tipos de estruturas costeiras e condições fronteira, sob a ação da agitação marítima variável no espaço e no tempo (Silva, 2010 (Coelho, 2005). (Silva, 2010). ...
O litoral de Portugal revela graves problemas de erosão que se relacionam
com a existência de défices sedimentares significativos. Em 2014, o GTL
(Grupo de Trabalho do Litoral) definiu como principal estratégia de defesa
costeira para o litoral português a reposição do balanço sedimentar, através de
alimentações artificiais de sedimentos. Nesse sentido, torna-se essencial o
estudo e modelação da evolução da linha de costa de forma a prever o
desempenho da alimentação, servindo de suporte à definição de cenários de
intervenção.
A morfologia que o litoral adquire é dependente do transporte de sedimentos
que ocorre ao longo da costa. Os sedimentos são distribuídos por ação das
ondas, correntes e ventos. No entanto, as características da agitação incidente
são consideradas o principal agente modelador e o maior responsável pela
capacidade de transporte de sedimentos. Os sedimentos podem adquirir
movimentos paralelos ou perpendiculares à linha de costa. Os movimentos
perpendiculares à linha de costa refletem o comportamento a curto prazo da
evolução morfológica do litoral e os movimentos paralelos estão associados às
alterações da linha de costa a longo termo.
O presente trabalho teve como principal objetivo o estudo do impacto das
alimentações artificiais, como medida de defesa costeira, na evolução da
morfologia do litoral. Analisou-se como ocorre a distribuição espacial e
temporal dos sedimentos induzidos pela alimentação artificial de sedimentos
ao longo da costa, para diferentes tipos de praia, em função das
características da agitação incidente. Para tal utilizou-se o modelo numérico
LTC (Long-Term Configuration). Assim, avaliou-se o impacto que a
alimentação artificial de sedimentos provoca na evolução da linha de costa em
planta, na geometria dos perfis transversais e nas variações de altimetria da
região modelada. De forma a obter-se o impacto da alimentação artificial
comparou-se a situação de evolução natural da linha de costa (sem realizar
alimentação artificial) com a situação de ser realizada a adição artificial de
sedimentos. Para além disso, tentou-se avaliar a velocidade de transporte do
centro de gravidade da alimentação artificial de sedimentos, de forma a
antecipar o tempo de permanência das alimentações e a necessidade de
proceder a novas alimentações.
O estudo realizado demonstra que a realização da alimentação artificial de
sedimentos provoca, de um modo geral, um impacto benéfico na morfologia,
atenuando efeitos negativos da erosão sobre a evolução da linha de costa,
contrariando os défices sedimentares existentes. Esse impacto repercute-se
na diminuição do recuo da linha de costa e no aumento da robustez do perfil
transversal. Por último, a análise qualitativa do impacto da alimentação artificial
de sedimentos em três troços costeiros da faixa continental portuguesa
também revela o efeito benéfico da alimentação artificial de sedimentos
... Vulnerability reveals the characteristics and conditions of the community, system or asset that make it vulnerable to damage caused by coastal erosion hazards [9]. Coelho (2005) developed a methodology for assessing the risk of coastal erosion. This method was chosen in this study because there is no other complex model which in its formulation allows for rapid application at the research site by adjusting the number and detail of parameters based on the availability of field data. ...
... This study uses the methodology proposed by Coelho (2005) to assess vulnerability, consequences and risks associated with coastal erosion. This method is focuses specifically on coastal erosion, rather than most of other methods that generally concerned on sea level rise [12]. ...
... Coastal erosion risk assessment divides into two parts. The first is a vulnerability assessment that estimates, qualitatively and quantitatively, the level of vulnerability of a coastal area to coastal erosion [13]. This assessment focuses on the physical characteristics of the coastal area and the potential threats to erosive agents. ...
Coastal erosion is the process of land erosion in coastal areas due to waves and ocean currents which reduce land and can adversely affect socio-economic activities in coastal areas. Coastal erosion risk assessment in the estuary is a development of previous research, because the erosion and accretion processes do not only occur along the shoreline, but also on the side facing river water bodies, due to the confluence of fluvial and marine processes. The landward shift of the shoreline in the Muara Asam Asam coastal area has reached 90 meters in the last 28 years, and has been detrimental because the area is a densely populated area with major economic activities in the fisheries and agriculture sectors. This study aims to determine the coastal erosion risk level zones based on the relationship among vulnerability and consequence parameters, through distance decay weighted based method. The results indicate that Muara Asam Asam has high risk zones of coastal erosion, especially in densely populated residential areas and dry land agriculture on the west side of the estuary, due to the lack of implementation of preventive measures through hard coastal structure and coastal zoning policy to protect socio-economic activities and coastal ecological environments.
... In this study, the classic Bruun equation (Equation (1)) was applied on Barra-Poço da Cruz coastal stretch (Aveiro region), using bathymetry and UAV photogrammetry DEM data ( Figure 1b). The results were compared with [57]'s study, which performed a Bruun rule analysis in the same region. Profiles for the GEE Model (BRGM) were created with the values detailed in this study. ...
... Profiles for the GEE Model (BRGM) were created with the values detailed in this study. However, there are some bathymetric and topographic differences between the profiles performed by [57] and the present analysis because it was necessary to adapt the length of some profiles to get similar values of height and depth. The topographic and bathymetric data used have two sources, the COSMO Program [58] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [59] (bathymetry) with 82.4 m of spatial resolution. ...
... The topographic and bathymetric data used have two sources, the COSMO Program [58] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [59] (bathymetry) with 82.4 m of spatial resolution. Subsequently, a Spearman correlation analysis between the GEE Bruun rule results and the previous study [57] was performed. After the validation process, was tested for the area a scenario of sea-level rise of 1.21 m, considering the contribution of the Antarctic Ice Sheet (AIS) melting process (AIS = 60 cm) [60]. ...
Sea-level rise is a problem increasingly affecting coastal areas worldwide. The existence of free and open-source models to estimate the sea-level impact can contribute to improve coastal management. This study aims to develop and validate two different models to predict the sea-level rise impact supported by Google Earth Engine (GEE)-a cloud-based platform for planetary-scale environmental data analysis. The first model is a Bathtub Model based on the uncertainty of projections of the sea-level rise impact module of TerrSet-Geospatial Monitoring and Modeling System software. The validation process performed in the Rio Grande do Sul coastal plain (S Brazil) resulted in correlations from 0.75 to 1.00. The second model uses the Bruun rule formula implemented in GEE and can determine the coastline retreat of a profile by creatting a simple vector line from topo-bathymetric data. The model shows a very high correlation (0.97) with a classical Bruun rule study performed in the Aveiro coast (NW Portugal). Therefore, the achieved results disclose that the GEE platform is suitable to perform these analysis. The models developed have been openly shared, enabling the continuous improvement of the code by the scientific community.
... If the quantity of sediments leaving a coastal stretch is balanced by the same quantity of sediments coming in, the system is in a dynamic equilibrium, not resulting in erosion or accretion. But if the sediment balance is not maintained, erosion or accretion occurs, representing, respectively, the retreat or advance of the shoreline position [2,3]. ...
... Due to the complexity of the coastal processes and taking into account the incompatibility of their time scales of interest, it is common to divide the assessment of the littoral sediments transport in two components [17,18]: Longitudinal transport, where sediments are transported in a direction parallel to the coastline; and cross-shore transport, where sediments are transported in a direction perpendicular to the coastline [19]. The crossshore sediment transport reflects the short-term morphological evolution (storm to seasonal behavior) and the longshore sediment transport is associated with long-term shoreline changes, related to years or decades [3,14,19]. ...
... The numerical LTC model, developed by Coelho [3], was specifically designed for sandy beaches, where the main cause of medium-term shoreline evolution is the longshore sediment transport gradients. The latter mainly depends on the wave climate and the domain boundary conditions. ...
Serious erosion problems related to significant negative sediments budgets in the coastal systems are referred worldwide. Artificial nourishments are a coastal erosion mitigation strategy that allow for a decrease in those negative budgets by adding sediment to the coastal system. Thus, it is essential to understand and adequately model the shoreline response after a nourishment operation, in order to support the definition of the best intervention scenarios. The main goal of this work was to study the artificial nourishment effects on the longshore sediment transport and consequently on the morphological evolution at the intervention site and nearby areas, in a time horizon of 5 years. The longshore transport of the nourished sediments was evaluated, aiming to contribute to the evaluation of the sediment’s permanence at the deposition site and the frequency required for new nourishments. The shoreline evolution numerical long-term configuration (LTC) model was applied in order to evaluate the spatial and temporal distribution of the nourished sediments along the coast, considering different types of beaches and incident wave climates. The adopted approach is generic and supported by simple numerical models, which can be useful for preliminary site-specific evaluations. The results show that the nourishment impact is mainly observed nearby the intervention site. It is highlighted that higher longshore sediment transport rates are associated with more energetic wave climates, but not necessarily with incident waves more oblique to the shoreline.
... In this study, the classic Bruun equation (Eq. 1) was applied on the Portuguese coastal stretch, between Barra and Poço da Cruz beaches (Aveiro region), using bathymetry and UAV photogrammetry DEM data (Figure 1). The results were compared with [58]'s study, which performed a Bruun Rule analysis in the same region. Profiles for the GEE Model (BRGM) were created with the values detailed in this study. ...
... Profiles for the GEE Model (BRGM) were created with the values detailed in this study. However there are some bathymetric and topographic differences between the profiles performed by [58] and the present analysis because it was necessary to adapt the length of some profiles to get similar values of height and depth. The topographic and bathymetric data used have two sources, the COSMO Program [59] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [60] (bathymetry) with 82.4 m of spatial resolution. ...
... The topographic and bathymetric data used have two sources, the COSMO Program [59] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [60] (bathymetry) with 82.4 m of spatial resolution. Subsequently, a Spearman correlation analysis between the results of the GEE Bruun Rule and the previous study [58] was performed. After the validation process, was tested for the area a scenario of sea level rise of 1.21 m, considering the contribution of the ice sheets melting process (AIS = 60 cm) [61]. ...
Sea-level rise is a problem increasingly affecting coastal areas worldwide. The existence of Free and Open-Source Models to estimate the sea-level impact can contribute to better coastal man-agement. This study aims to develop and to validate two different models to predict the sea-level rise impact supported by Google Earth Engine (GEE) – a cloud-based platform for planetary-scale environmental data analysis. The first model is a Bathtub Model based on the uncertainty of projections of the Sea-level Rise Impact Module of TerrSet - Geospatial Monitoring and Modeling System software. The validation process performed in the Rio Grande do Sul coastal plain (S Brazil) resulted in correlations from 0.75 to 1.00. The second model uses Bruun Rule formula implemented in GEE and is capable to determine the coastline retreat of a profile through the creation of a simple vector line from topo-bathymetric data. The model shows a very high cor-relation (0.97) with a classical Bruun Rule study performed in Aveiro coast (NW Portugal). The GEE platform seems to be an important tool for coastal management. The models developed have been openly shared, enabling the continuous improvement of the code by the scientific commu-nity.
... In this study, the classic Bruun equation (Equation (1)) was applied on Barra-Poço da Cruz coastal stretch (Aveiro region), using bathymetry and UAV photogrammetry DEM data (Figure 1b). The results were compared with [57]'s study, which performed a Bruun rule analysis in the same region. Profiles for the GEE Model (BRGM) were created with the values detailed in this study. ...
... Profiles for the GEE Model (BRGM) were created with the values detailed in this study. However, there are some bathymetric and topographic differences between the profiles performed by [57] and the present analysis because it was necessary to adapt the length of some profiles to get similar values of height and depth. The topographic and bathymetric data used have two sources, the COSMO Program [58] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [59] (bathymetry) with 82.4 m of spatial resolution. ...
... The topographic and bathymetric data used have two sources, the COSMO Program [58] (topography) with 1 m of spatial resolution and the Portuguese Hydrographic Institute [59] (bathymetry) with 82.4 m of spatial resolution. Subsequently, a Spearman correlation analysis between the GEE Bruun rule results and the previous study [57] was performed. After the validation process, was tested for the area a scenario of sea-level rise of 1.21 m, considering the contribution of the Antarctic Ice Sheet (AIS) melting process (AIS = 60 cm) [60]. ...
Sea-level rise is a problem increasingly affecting coastal areas worldwide. The existence of Free and Open-Source Models to estimate the sea-level impact can contribute to better coastal management. This study aims to develop and to validate two different models to predict the sea-level rise impact supported by Google Earth Engine (GEE)-a cloud-based platform for planetary scale environmental data analysis. The first model is a Bathtub Model based on the uncertainty of projections of the Sea-level Rise Impact Module of TerrSet-Geospatial Monitoring and Modeling System software. The validation process performed in the Rio Grande do Sul coastal plain (S Brazil) resulted in correlations from 0.75 to 1.00. The second model uses Bruun Rule formula implemented in GEE and is capable to determine the coastline retreat of a profile through the creation of a simple vector line from topo-bathymetric data. The model shows a very high correlation (0.97) with a classical Bruun Rule study performed in Aveiro coast (NW Portugal). The GEE platform seems to be an important tool for coastal management. The models developed have been openly shared, enabling the continuous improvement of the code by the scientific community.
... The model developed to integrate the effects of cross-shore and longshore sediment transport processes relies on the assimilation of the results generated by the numerical models LTC (Coelho, 2005) and CS-Model which, respectively, simulate medium to long-term longshore and cross-shore sediment transport processes based on a user-defined set of inputs. ...
... The LTC (Long-Term Configuration) is a one-line model designed for application to sandy beaches. The evolution of the shoreline position in the LTC results from the gradients in longshore sediment transport driven by the action of waves, water levels and boundary conditions at the modelled domain (Coelho, 2005;Coelho et al., 2007;Lima and Coelho, 2017;Ferreira and Coelho, 2021). The model employs a dataset defined by the user, encompassing calculation times, characteristics of offshore waves, sediment properties, bathymetry and topography of the study area, boundary conditions of the modelled grid, and water levels. ...
... Based on the modelling outputs presented before, this work developed the complete evaluation of the proposal, comparing the potential costs and benefits of each alternative design. To this end, the evolution of the shoreline for the reference scenario (which consists of the natural progression of the shoreline assuming the maintenance of the current coastal protection conditions) and four design alternatives (combining different breakwater lengths and distances to the shoreline) was modelled using the LTC software (Coelho 2005;Lima and Coelho 2017). These outputs were then overlapped with the land use and land cover (LULC) map for the area of interest to determine expected eroded and flooded areas, over a 20-year time horizon. ...
... After identifying the LULC classes present in the model domain, it was possible to determine their exposure to coastal flooding and erosion. For this, the numerical modelling of the coastal morphodynamics was performed in LTC -Long-Term Configuration software (Coelho 2005;Lima and Coelho 2017), which enables forecasting the evolution of the shoreline based on local hydrodynamics and topobathymetric conditions, after being calibrated and validated with historical data. The model grid points were defined as spaced 20 m in both directions. ...
Defining the most suitable intervention to mitigate coastal hazards in a specific area, under an integrated coastal management strategy, is complex for several reasons including the lack of stakeholders’ consensus. In this respect, Cost-Benefit Analyses (CBAs) can help decision-makers to better understand the environmental, social and economic implications of a planned intervention. Nevertheless, CBAs are not yet largely applied in coastal management studies, as could be expected. Hence, this work aims to consolidate the use of a CBA to support coastal management decisions, considering its application to a real case study. The case study consists in evaluating the long-term impacts, benefits and costs of a detached breakwater for the protection of a coastal village located on the Portuguese northwest coast against flooding and erosion. This assessment was made based on the estimation of the costs of the structure and the benefits associated with the protection of the coastal community and natural areas, considering morphodynamics’ forecasts determined through numerical modelling. Out of several configurations defined based on length (L; in meters) and distance to the shoreline (D; in meters), four detached breakwater scenarios were selected. Results demonstrate that scenario L200D200 can be a feasible solution with overall low costs and low benefits; L300D400 can be an alternative solution with higher costs but higher benefits too. The consolidation of the CBA described is a step forward to improving the expedition of future analysis and proof of its potential in what concerns analysis at the local scale.
... Esta ferramenta, desenvolvida no âmbito do trabalho de Lima (2018), tem a capacidade de avaliar a posição da linha de costa a médio-longo termo, e permitir a análise de cenários hipotéticos de intervenção na zona costeira, calculando o custo-benefício para cada cenário testado, por comparação com o cenário de não-intervenção. A ferramenta é composta por 3 módulos, que se integram entre si: módulo de evolução da linha de costa (Coelho, 2005;Lima, 2018); o módulo de pré-dimensionamento de obras de defesa costeira XD-COAST (Lima, 2011); e por último, o módulo de análise de custo-benefício. ...
... Esta ferramenta, desenvolvida no âmbito do trabalho de Lima (2018), tem a capacidade de avaliar a posição da linha de costa a médio-longo termo, e permitir a análise de cenários hipotéticos de intervenção na zona costeira, calculando o custo-benefício para cada cenário testado, por comparação com o cenário de não-intervenção. A ferramenta é composta por 3 módulos, que se integram entre si: módulo de evolução da linha de costa (Coelho, 2005;Lima, 2018); o módulo de pré-dimensionamento de obras de defesa costeira XD-COAST (Lima, 2011); e por último, o módulo de análise de custo-benefício. Lima (2018) aplicou a ferramenta COAST a um caso de estudo hipotético, permitindo comprovar a versatilidade e potencialidades da ferramenta. ...
Ao longo dos séculos, os povos têm vindo a fixar-se nas zonas litorais, pelas oportunidades que oferecem, quer ao nível económico, quer ao nível de bem estar e lazer. No entanto, o litoral também se encontra exposto a graves perigos. A erosão afirma-se como um dos principais riscos associados a zonas costeiras. Este fenómeno pode causar elevados prejuízos, com particular incidência nas frentes urbanas, e potenciar consequências derivadas de fenómenos adjacentes, como cheias e galgamentos. É, portanto, essencial o aprofundamento do estudo de estratégias de previsão, prevenção e mitigação deste fenómeno. O COAST (Coast Optimization Assessment Tool) é uma ferramenta de análise integrada de custo-benefício de intervenções costeiras. Esta ferramenta, desenvolvida no âmbito do trabalho de Lima (2018), tem a capacidade de avaliar a posição da linha de costa a médio-longo termo, e permitir a análise de cenários hipotéticos de intervenção na zona costeira, calculando o custo-benefício para cada cenário testado, por comparação com o cenário de não-intervenção. A ferramenta é composta por 3 módulos, que se integram entre si: módulo de evolução da linha de costa (Coelho, 2005; Lima, 2018); o módulo de pré-dimensionamento de obras de defesa costeira XD-COAST (Lima, 2011); e por último, o módulo de análise de custo-benefício.
... The Portuguese Northwest coast is exposed to the Atlantic Ocean wave climate, characterized by significant wave heights (Hs) between 2 m and 2.5 m, inducing a potential net longshore drift estimated to be around 1.1x10 6 m 3 /year directed towards South (Andrade et al., 2002;Coelho, 2005, Santos et al., 2014. Storms come predominantly from the NW sector and occur during the maritime winter months (from October to March) with significant wave heights that can exceed 8 m and can persist 5 days (Costa et al., 2001). ...
... These scenarios enabled the examination of factors such as bypass volumes, alongshore and cross-shore deposition sites, frequency of interventions and number of outlets for the fixed solutions. The LTC numerical model (Coelho, 2005) was applied to assess the shoreline evolution and the CS-Model (Larson et al., 2016) was used to evaluate the cross-shore beach profiles evolution over a period of 30 years ( Figure 3). A baseline scenario (BS) was defined considering the results of the historical interventions performed on the coastal sectors, corresponding to the deposition of 5x10 6 m 3 /year of sediments in the area designated as BS ( Figure 1). ...
To mitigate coastal erosion in the sectors Barra-Vagueira and Figueira da Foz-Leirosa (NW of Portugal), Portuguese coastal authority has promoted the discussion on the feasibility of implementing a sand bypassing system to restore natural littoral sediment transport. This study synthesizes the main results of the proposed solutions for Aveiro and Figueira da Foz tidal inlets. The methodology to develop the study compromised tree main phases that included the historical characterization of the study area, the preliminary design of different sand bypassing solutions for each coastal inlet and the discussion of their economic feasibility. The physical performance of the sand bypass solutions demonstrated that several bypassing solutions are technically viable to mitigate coastal erosion. However, it was found that the solution is economically viable only at the coastal sector Figueira da Foz-Leirosa.
... The location factor (F1) includes variables that describe the coastal characteristics of the environment, such as the elevation (V1) of land with respect to sea level [36][37][38][39], the orientation (V2) of the percentage of the perimeter without obstructions of the wind wave, the distance from the coastline (V3) [38,40], and geomorphology (V4), since wave energy is related to erosion capacity, where relief and vertical movements of the earth are considered indicators of flood risk [35,36]. ...
... The location factor (F1) includes variables that describe the coastal characteristics of the environment, such as the elevation (V1) of land with respect to sea level [36][37][38][39], the orientation (V2) of the percentage of the perimeter without obstructions of the wind wave, the distance from the coastline (V3) [38,40], and geomorphology (V4), since wave energy is related to erosion capacity, where relief and vertical movements of the earth are considered indicators of flood risk [35,36]. ...
Accidents in port areas in the Gulf of Mexico have had great economic costs, since this is an area exposed to extreme phenomena. Tropical cyclones or cold fronts, also known as Tehuantepecers, result in intense winds and waves that impact the coastal infrastructure. The chemical risk associated with extreme winds and waves for the fuel storage tanks of the facility of the Port of Veracruz, the main Mexican port in the Gulf of Mexico, was evaluated with a historical analysis of accidents as a tool to identify significant factors in disasters and establish risk acceptance criteria. It was found that the critical hazard threshold for Veracruz corresponds to winds stronger than 160 km/h (44 m/s) that may result in coastal waves of more than 5 m high. The vulnerability to these phenomena was calculated with the vulnerability index (VI), considering the structural, functional, and chemical factors in the infrastructure, including exposure levels. By means of a risk matrix, it was determined that gasoline storage tanks have a moderate chemical risk, since exposure to the extreme wind wave hazard is low, and diesel tanks are at low risk. These assessments are important elements to consider in the expansion plans for the Port of Veracruz.
... Portugal possui uma costa extensa, diversificada e pouco sinuosa onde predominam os litorais de erosão (i.e., arribas, plataformas de abrasão) sobre os de acumulação (i.e., praias, dunas, estuários, ilhas barreira, lagunas, rasos de maré, sapais Face ao exposto, e com o objetivo de tentar mitigar problemas de dimensão local ou regional e de proteger pessoas e bens, foi (e continua a ser) necessário tomar medidas precaucionárias face ao iminente risco de galgamento e inundação costeira, sendo disso exemplo: (i) a retirada e recolocação das pessoas e bens das áreas vulneráveis; (ii) a realização de obras denominadas "flexíveis" sobre o litoral vulnerável ou já em condição de erosão, como alimentações artificiais de praias, ripagem de areias, construção/recuperação de dunas; (iii) ou a realização de obras de engenharia rígidas, para manutenção da posição da linha de costa, como esporões, obras aderentes (paredões), quebra-mares e enrocamentos ou, ainda, estabilização de arribas. Todas estas possibilidades devem ser bem avaliadas antes de serem aplicadas (Coelho, 2005), pois qualquer uma delas representa uma interferência com um meio altamente dinâmico e, consequentemente, os resultados a longo prazo são difíceis de estimar, pelo que é essencial uma compreensão dos fenómenos que ocorrem na costa, tais como o regime de agitação marítima, as correntes litorais e o transporte sedimentar que resultam na sua variabilidade morfológica (Komar, 1998). ...
... Em Portugal, até ao final da década de 80 do século XX, associava-se, em larga medida, a proteção costeira à construção de obras de engenharia rígidas, para reduzir os riscos de exposição das frentes edificadas à ação das ondas e marés, ao invés de se apostar em políticas de ordenamento que, naturalmente, têm objetivos muito mais vastos do que a redução desses riscos (embora tenham, também, de os equacionar e reduzir), mas que pressupõem decisões políticas de grande responsabilidade pelas profundas implicações de natureza social, cultural, económica e técnica, nas atuais e futuras gerações, numa ótica local, regional ou até global (Veloso-Gomes & Taveira- Pinto, 1997;Coelho, 2005). ...
This dissertation is focused on the evolution of the S. João da Caparica beach-dune system after the most recent interventions that were required in face of the coastal erosion that affects it since the mid-20th century. The main objectives are the characterization and interpretation of the morphological and volumetric evolution of the beach-dune system following the last nourishment operation and the reconfiguration of the aeolian sand fences, the characterization of sediments, and the investigation of relations between the morphological and volumetric evolution of the dune, the wind regime and precipitation. Three types of data — topographic, sedimentological and wind — compiled from several authors and entities and from two field campaigns were used in the scope of this dissertation.
The topographic data allowed to calculate morphological indicators and to characterize the seasonal evolution of the beach, as well as to quantify evolution trends at a longer time scale. It also allowed the construction of altimetric difference distribution maps and the determination of volumetric retention, sediment budget and accretion and erosion volume in the beach and dune. The dune, berm and beach face samples were subjected to grain-size analysis to extract the main statistical distribution parameters. Wind characterization allowed the determination of the effective wind, which, in turn, translated into a proxy of the potential solid transport. For the same periods the patterns of dune volumetric evolution were compared with the aeolian solid transport potential, considering the dry surface and all the effective winds, and then reducing the series to winds blowing from sea to land. In a second approach the influence of sand moisture determined by precipitation, which influences the threshold shear velocity required to maintain wind transport was also considered.
Results indicate that S. João da Caparica beach acquires, during most of the time, reflective characteristics and, occasionally, characteristics closer to the dissipative extreme, simplifying its morphology. The southern sector is more susceptible to erosion and is more fragile in retaining sands. The monotony of the granulometric results demonstrates that sediment texture has remained unchanged for at least 30 years; the beach nourishment of September 2014 and October 2019 having left no recognisable signature on the samples analysed. The last beach nourishment, completed in September 2019, imposed a disturbance to the system which was, however, followed by the resumption of the previously established erosive trend. The longevity limits of the artificial nourishment were estimated to 4 years, considering a threshold volume of 160 000 m3. Overall, the dune system is accreting, at rates of +3 500 m3/year, due to the ReDuna project restoration intervention. Accretion was more intense and spatially more continuous in the dune domain located closer to the beach, adjacent to the row of sand fences bordering the upper beach. Values of potential aeolian transport and volumetric variation observed in the two outermost domains of the dune system showed high correlation. The introduction of humidity as a factor of inhibition of solid transport produced results below the expected due to the parameterization methodology adopted. It was not possible to objectively conclude on the relationships between berm width (which conditions fetch) and aeolian solid transport.
... Depth of closure (DoC) used in this study was estimated from profile convergence (s < 0.15 m) and is-9.3 m (CD) (Figure 7). This depth is lower than previous wavebased empirical estimates of DoC for the same area, which can vary from −8.5 m CD to −17 m CD [28,40,41]. Discrepancies are mostly related to the different approaches (empirical versus morphological) and time scale of the analyses [42]. ...
... Depth of closure (DoC) used in this study was estimated from profile convergence (s < 0.15 m) and is-9.3 m (CD) (Figure 7). This depth is lower than previous wave-based empirical estimates of DoC for the same area, which can vary from −8.5 m CD to −17 m CD [28,40,41]. Discrepancies are mostly related to the different approaches (empirical versus morphological) and time scale of the analyses [42]. ...
Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 106 m3 shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km2 and 12 km2, respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 106 m3) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere.
... É necessário realizar um trabalho de projeção que passa também por identi car os locais onde a linha de costa vai regredir com menos intensidade, permitindo uma ocupação com menos custos, e os locais de maior risco, promovendo a retirada das populações. Nesta análise, o modelo numérico LTC -Long-Term Con guration (COELHO et al., 2004, COELHO, 2005, COELHO et al., 2007, SILVA et al., 2011, BAPTISTA et al., 2014, que tem vindo a ser desenvolvido com aplicabilidade para o local em estudo, permitirá facilitar a identi cação do custo e do benefício de cada hipótese, o que é fundamental, para avaliar a relação entre o ganho que se retira da construção da obra e o prejuízo econômico da sua realização e manutenção. Só esta análise (complexa) permite sustentar tecnicamente as opções políticas a adotar. ...
... Como referido, as situações comuns de recolha de dados originam 240 registos mensais, mas facilmente se constata, pela análise do grá co da Figura 4, que é raro o mês com esse número de registos. Os meses com número de registos superior a 240 revelam necessariamente a ocorrência de temporais(COELHO, 2005). ...
presente publicação surge da necessidade de um melhor
conhecimento dos processos e impactos associados às Ressacas do
Mar/Temporais, especialmente, tratando-se do litoral brasileiro.
O conhecimento prévio dos fenômenos naturais de alta energia
é importante para prevenção de impactos indesejados, pois, em
alguns casos, as consequências podem ultrapassar o limiar que
envolve os danos ao patrimônio edi cado, ocasionando vítimas.
O livro aborda diversas formas pelas quais as ressacas do
mar/ temporais são estudadas no Brasil e no mundo, contribuindo
para uma melhor compreensão do assunto, que, por vezes,
é bastante confuso e controverso, especialmente no que concerne
à sua origem e de nição. De forma geral, esta publicação foi
construída a partir da preocupação dos editores em transmitir
aos interessados uma visão integrada de algumas re exões acadêmicas
e experimentos cientí cos que envolvem análise histórica,
riscos e vulnerabilidade costeira, determinação de limiares para
ocorrência de impactos, aplicações metodológicas e políticas de
gestão costeira.
... Em cenários de tempestade as zonas costeiras desempenham um papel fundamental na proteção de pessoas e bens, servindo de barreira à propagação dos riscos costeiros e absorvendo as ações energéticas do mar (Dias, 2005). O clima de agitação ao longo do litoral português apresenta uma elevada capacidade energética, com valores elevados de deriva litoral, que associados à redução do fornecimento sedimentar devido à atividade antrópica promovem o agravamento dos fenómenos de erosão, refletindo-se numa situação generalizada de recuo da linha de costa e provocando em alguns locais uma perda significativa do território (Coelho, 2005;Veloso-Gomes, 2007, Santos et al., 2014. O presente estudo teve como objetivos principais prever as características de eventos futuros de tempestade na zona costeira de Aveiro e avaliar os impactos que as eventuais variações no clima de agitação marítima devido ao efeito das alterações climáticas provocam no transporte longitudinal de sedimentos. ...
... Em cenários de tempestade as zonas costeiras desempenham um papel fundamental na proteção de pessoas e bens, servindo de barreira à propagação dos riscos costeiros e absorvendo as ações energéticas do mar (Dias, 2005). O clima de agitação ao longo do litoral português apresenta uma elevada capacidade energética, com valores elevados de deriva litoral, que associados à redução do fornecimento sedimentar devido à atividade antrópica promovem o agravamento dos fenómenos de erosão, refletindo-se numa situação generalizada de recuo da linha de costa e provocando em alguns locais uma perda significativa do território (Coelho, 2005;Veloso-Gomes, 2007, Santos et al., 2014 ...
A tendência regressiva que se observa no litoral português combinada com a prevista subida do nível médio da água do mar e a eventual alteração da frequência e intensidade de tempestades, causadas pelas alterações climáticas, coloca em risco pessoas e bens, obrigando a uma gestão fundamentada das zonas costeiras com o objetivo de proteger o património económico, social e ambiental. A gestão das zonas costeiras passa pela previsão das tendências futuras do regime de agitação marítima com o objetivo de se perceber como irão evoluir os eventos de tempestade e as taxas de transporte sólido de sedimentos (deriva litoral). Este trabalho apresenta os resultados de um estudo que teve como objetivos caracterizar os eventos de tempestade e o transporte sedimentar longitudinal na região costeira de Aveiro (trecho Barra-Vagueira, no Noroeste de Portugal), para diferentes cenários de alterações climáticas. O estudo apresentado permite concluir que os eventos de tempestade ainda que menos frequentes, serão mais intensos para os cenários de alterações climáticas considerados, e os valores líquidos do transporte sólido longitudinal de Norte para Sul tendem a ser menores no futuro.
... Various vulnerability assessment tools are employed to support climate risk management and adaptation. These include videotapeassisted vulnerability analysis (AVVA), a quick and low-cost approach to meet data gaps in coastal areas (Coelho, 2005); the coastal zone simulation model (COSMO) (CZMC and Resource Analysis, 1994); and index-based methodologies, developed as a rapid and consistent way to characterize the relative vulnerability of the coast. Index-based approaches are preferred as they support the integration and combination of multiple variables, capturing various levels and dimensions of vulnerability. ...
... Offshore wave climate is characterized by a highly energetic wave regime due to its exposure to the waves generated in the North Atlantic. The predominant wave direction is from WNW and NW, with an average significant wave height of 2 m and an average peak period of 11 s, but during winter and transition periods, the average significant wave height and peak period exceeds 4 m and 11 s, respectively (Coelho, 2005;Plecha et al., 2012;Silva et al., 2012). Storms that hit the coast are characterized by significant wave height above 5 m and peak periods that may exceed 16 s, predominantly from NW and SW (IH, 1990;Vitorino et al., 2002). ...
... Este artigo tem como objetivo geral o resumo do trabalho relativo ao estudo de evolução da linha de costa no litoral de Quarteira, realizado com a intenção de definir soluções que assegurem a posição da linha de costa atual e que, preferencialmente, também potenciem o aumento da largura de praia (Figura 1). (Coelho, 2005). Com o objetivo de caracterizar e reproduzir o trecho costeiro neste modelo, foi avaliada a evolução do litoral costeiro quanto à construção de estruturas de defesa costeira e ao registo histórico de taxas de recuo. ...
Este trabalho apresenta os resultados das projeções da linha de costa no horizonte 2020-2070, para diferentes cenários de restruturação do campo de esporões de Quarteira, com o objetivo de manter a sua posição atual e, idealmente, aumentar a largura de praia. Após a caracterização física da área de estudo e calibração do modelo numérico de evolução da linha de costa,
realizaram-se testes preliminares para avaliação da sensibilidade do modelo, tendo-se convergido na definição de oito cenários de intervenção. Os cenários simulados avaliaram o efeito da eliminação de alguns esporões existentes e o prolongamento de outros, e a sua conjugação simultânea com operações de alimentação artificial de sedimentos. Todos os cenários foram replicados considerando a subida do nível do mar por efeito das alterações climáticas. Os resultados antecipam o agravamento da situação de referência nos próximos anos devido ao défice sedimentar verificado, mas a retirada de esporões alternados e o prolongamento de outros remanescentes demonstra cumprir o objetivo quando se preveem realizar alimentações artificiais periódicas num volume de 200 000 m3/biénio.
... Relativamente ao modelo LTC (Coelho, 2005), o mesmo, tal como o anterior, foi elaborado para praias arenosas e considera que o transporte sedimentar longitudinal e as condições de fronteira nos extremos da grelha modelada são as principais causas de alteração na zona costeira. Difere do LITMOD na representação da linha de costa, em que o LTC admite um ajuste do perfil ativo com as zonas adjacentes, pelo que a posição daquela linha depende também da batimetria e da topografia em cada perfil transversal. ...
O "Estudo de caracterização e viabilidade de um quebramar destacado multifuncional em frente à Praia da Vagueira", efetuado pelo consórcio LNEC-UAveiro-IST para a Agência Portuguesa do Ambiente (APA) incluiu a modelação numérica da evolução da linha de costa. Neste trabalho apresentam-se os principais resultados dessa modelação, que recorreu aos modelos numéricos de evolução da linha de costa, do tipo "1-linha", LITMOD e LTC. O modelo LITMOD (Vicente e Clímaco, 2003) é um modelo numérico unidimensional em que a evolução da costa é representada pelas variações de posição da linha de água, as quais são calculadas, em cada célula em que se divide o trecho de praia, a partir das diferenças de caudal sólido que nela penetra e a abandona num curto intervalo de tempo, admitindo-se que o perfil transversal no seu avanço ou recuo se desloca paralelamente a si próprio, sem alteração de forma. Este modelo tem a possibilidade de modelar quebramares destacados submersos (QMDs). Para tal, o modelo inclui a ação das ondas refratadas, difratadas e transmitidas sobre o QMD, este último fenómeno exigindo a introdução de um coeficiente de transmissão. O cálculo do Kt foi realizado com três fórmulas empíricas e a partir de resultados do modelo numérico DREAMS (Canelas et al., 2020), que entra em conta com os efeitos de refração, difração e rebentação de ondas (através da limitação da altura de onda sobre a estrutura em função do bordo livre). Relativamente ao modelo LTC (Coelho, 2005), o mesmo, tal como o anterior, foi elaborado para praias arenosas e considera que o transporte sedimentar longitudinal e as condições de fronteira nos extremos da grelha modelada são as principais causas de alteração na zona costeira. Difere do LITMOD na representação da linha de costa, em que o LTC admite um ajuste do perfil ativo com as zonas adjacentes, pelo que a posição daquela linha depende também da batimetria e da topografia em cada perfil transversal. A área de estudo comum e de modelação matemática estende-se, a norte, desde o molhe sul da Barra de Aveiro até à Praia do Areão, a sul, numa extensão de 12 km. Por conveniência das condições de fronteira, no modelo LITMOD o domínio de cálculo estende-se mais para sul, até à Praia de Mira. Ambos os modelos utilizam informação da posição da linha de costa extraídas de ortofotomapas no trecho S. Jacinto-Praia do Areão. No caso do modelo LTC utilizou-se informação batimétrica obtida no âmbito do programa COSMO, de julho de 2018. Ambos os modelos utilizam ainda informação sedimentológica obtida de campanhas in situ. Neste resumo comparam-se os resultados obtidos com estes dois modelos numéricos, traduzidos por diferentes descritores da evolução da linha de costa, para diferentes configurações do quebramar destacado submerso.
... Coastline projections were simulated with the LTC, Long-Term Configuration, numerical model (Coelho, 2005). The model calibration relied on average shoreline rate-of-change, evaluated through shoreline position displacements between of 1958 and 2010 (Lira et al., 2016) and, considering previously validated wave climate data produced in WAVEWATCH-III (WWIII) spectral model for a similar period as the forcing agent (Dodet et al., 2010;GeoFCUL, 2021). ...
Coastal sandy areas are highly dynamic environments, where sediment transport driven predominantly by wave action define its morphology. More than 50% of the sandy coast of Portugal is under a significant recess of the coastline (Pranzini et al., 2015), where low-lying sandy coasts are most vulnerable when it comes to storm surges and flood risks (Santos & Miranda, 2006; Alves et al., 2011). Additional risks can be expected from climate change and its undesirable consequences, such as a projected increase in frequency and magnitude of extreme events, demanding an ever-increasing need for adaptation actions (SROCC, 2019).
In an effort to overcome the effects of climate change, the United Nations Intergovernmental Panel on Climate Change (IPCC) defined a series of future scenarios based on greenhouse gas concentration trajectories, designated as RCP (Representative Concentration Pathway). The present work aims to highlight the influence of climate change on the western Portuguese coastline, studying its effects in the future wave characteristics and in the sea level rise (SLR). Regarding the effects of climate change in the wave characteristics, two wave series generated considering the future RCP intermediate scenario (RCP4.5) and the most adverse (RCP8.5) were studied. Under these different forcing scenarios, the shoreline evolution of three littoral stretches were analyzed, with a total length of 43 km, due to their vulnerability to persistent erosion processes: Barra-Vagueira (Aveiro); Claridade-Leirosa (Figueira da Foz) and; São João-Fonte da Telha (Caparica coast).
... A aplicação de um modelo numérico (LTC; Coelho, 2005) para projeção de cenários de evolução da posição da linha de costa requer a caracterização física da área de interesse, o processamento dos dados recolhidos e a respetiva integração no domínio de cálculo. A posição da linha de costa é essencialmente definida pelos agentes forçadores (nível da superfície do mar e clima de agitação), através da aplicação da equação de continuidade aos balanços sedimentares. ...
Em Portugal, os trechos costeiros em risco (i.e., onde são detetados fenómenos de erosão ou de galgamentos e inundações que possam colocar em causa a segurança de pessoas e bens) estão identificados em diversos trabalhos científicos e definidos nas principais diretivas de ordenamento do litoral. Com efeito, estas zonas são com frequência alvo de diversos estudos prospetivos para fundamentar e garantir a adequabilidade das ações contínuas de intervenção, executadas pelas autoridades nacionais de gestão das zonas costeiras, com vista à prevenção e mitigação de riscos. Neste sentido, o presente trabalho identificou a necessidade e oportunidade de constituir, de forma sistemática e coerente, domínios de cálculo de modelação que permitam a qualquer momento iniciar a discussão de cenários de evolução da linha de costa para alternativas de intervenção (isoladas ou conjugadas) nas zonas litorais em risco. Para tal, constituiu-se um repositório com domínios de cálculo devidamente caracterizados e calibrados, que podem ser expeditamente reaplicados em estudos futuros. Não obstante as limitações inerentes à modelação numérica de processos hidro e morfodinâmicos, validou-se a utilidade do repositório criado, verificando a redução do tempo alocado à duplicação das tarefas de caracterização da física costeira e calibração dos modelos a cada nova análise.
... As ações das ondas e da deriva litorânea interferem no resultado final entre o volume de entrada e saída de sedimentos do sistema, isto é, no balanço sedimentar, resultando no comportamento de progradação (balanço sedimentar positivo), estabilidade (balanço sedimentar nulo) ou erosão (balanço sedimentar negativo) da linha de costa (Bird 2008 Dominguez et al. 2018), com a presença de pontais (Morales et al. 2001, Angulo et al. 2009, Dan et al. 2011, ou ainda, ocupados pelo homem (Sanchez-Arcilla et al. 1998, Dutrieux et al. 2000, Coelho 2005, Ribeiro 2008, Pereira & Coelho 2013, Silva et al. 2014) são ambientes mais vulneráveis à erosão costeira. ...
Este trabalho teve o objetivo de avaliar a influência da dinâmica das ondas e características locais nos processos erosivos na planície costeira do rio Itapicuru, no litoral norte do estado da Bahia. A modelagem da dinâmica costeira foi realizada com o programa Sistema de Modelagem Costeira do Brasil (SMC-Brasil) e envolveu o cálculo da refração de ondas e do transporte longitudinal de sedimentos ao longo do litoral. Os resultados da modelagem mostraram que as ondas de sudeste são determinantes na definição do transporte resultante, que é predominante para nordeste. Em apenas um trecho do litoral estudado, o transporte teve sentido sudoeste. Isso se deveu a influência de uma “cava” batimétrica presente na plataforma que foi responsável pela divergência de raios de ondas de sudeste. Também tiveram influência na refração das frentes de ondas a presença de altos batimétricos na desembocadura dos rios Itariri e Itapicuru, associadas às suas barras de desembocadura, que geraram a convergência e aumento da energia de ondas. O estudo da interação da dinâmica de ondas com as características da zona costeira permitiram identificar duas situações de maior probabilidade de ocorrência de erosão no trecho estudado: i) na região das desembocaduras dos rios Itariri e Itapicuru, que além de apresentarem alta variabilidade de posição, intrínseca a desembocaduras fluviais, têm uma maior energia de ondas incidentes, provocada pela refração causada por suas próprias barras de desembocadura; e ii) na região do povoado de Poças, onde se localiza a única divergência de deriva litorânea constatada no trabalho, que torna o balanço sedimentar negativo na costa, e ocorre em trecho estreito de uma península, que por esta razão, também é vulnerável à ocasional erosão fluvial provocada por um afluente do rio Itapicuru que corre na retaguarda da mesma. Os resultados desse trabalho mostram a importância da modelagem da dinâmica costeira em escala de detalhe, que permitiu, por exemplo, identificar a divergência de deriva litorânea presente no povoado de Poças. Conclui-se também pela importância de evitar a ocupação nos trechos costeiros vulneráveis, como aqueles próximos de desembocaduras fluviais e aqueles associados a penínsulas estreitas e outras formas de acumulação, como pontais.
... The morphological impacts of the different intervention scenarios idealized for each stretch were simulated by applying the first module of COAST, the shoreline evolution model, LTC (Coelho, 2005;Lima and Coelho, 2017;Lima and Coelho, 2019). The model allowed to obtain erosion/accretion patterns in addition to the position of the coastline on a time scale of 20 years, considering climate change (RCP4.5 -IPCC) and mean sea level rise (0.0075 m/year -Antunes, 2019). ...
Over the years, people have been settling in coastal areas, as they provide opportunities, both economically and in terms of well-being and leisure. However, the coastline is also exposed to serious problems of coastal erosion, particularly on urban fronts, increasing the consequences derived from adjacent phenomena such as overtopping and flooding. It is therefore essential to deepen the study of strategies for the prediction, prevention and mitigation of this phenomenon. In this sense, COAST (Coast Optimization Assessment Tool), a tool for integrated cost-benefit analysis of coastal interventions to mitigate erosion problems, was developed. The COAST4US project - Application of the COAST tool to the Portuguese coast - aims to contribute to the feasibility of applying this tool in real situations, contributing to an efficient mitigation of coastal erosion, and providing decision makers with more and better information. The project proposes to apply COAST to three stretches of coastline at high risk of coastal erosion on the Portuguese west coast: Aveiro, Figueira da Foz, and Costa de Caparica. The project is divided in several tasks, including scenario modeling, cost prediction and benefit assessment, being this work focused on benefit assessment by estimating the value of each beach, and analyzing the effectiveness of three nourishment scenarios.
... The Northwest Portuguese coast, where the coastal sector Esmoriz-Nazaré is located, is characterized by continuous sandy beaches with foredune systems which have been developed from rivers sediment supply and wave action ( Figure 1). The sector is exposed to a very energetic wave climate with mean values of significant wave height (Hs) between 2 m and 2.5 m (Andrade et al., 2002;Coelho, 2005). According to Santos et al. (2014), the wave climate at the West Portuguese coast promotes a North to South directed net littoral drift estimated to be around 1.1x10 6 m 3 /year. ...
The Northwest Portuguese coastal sector Esmoriz-Nazaré is exposed to a very energetic wave climate that promotes a net littoral drift estimated to be around 1.1x106 m3/year. This study aimed to characterize the littoral drift in the coastal sector Esmoriz-Nazaré, discussing past and future trends by applying two bulk longshore sediment transport formulas: CERC (1984) and Mil-Homens et al. (2013). Generically, the results present a longshore sediment transport variability at the study area. In spite of the differences between the considered formulas, both of them present similar trends along the coastal sector and for the past and future wave climates. In the future, mainly due to changes in the projected waves direction, the net littoral drift is expected to decrease.
... Araújo et al. [17] applied one-line models of GENESIS [18] in a case study to assess the impact of detached breakwaters on shoreline evolution. Guimarães et al. [19] adopted LTC [20] to estimate the long-term shoreline changes due to detached breakwaters under oblique wave action. Recently, de Macêdo et al. [21] carried out the geometric parameters of salients and tombolos behind reefs and breakwaters in a tropical mesotidal environment along the Central Brazilian Coast based on the relationship proposed by Klein et al. [22]. ...
Detached breakwaters are widely used for shore protection. The planforms of tombolos or salients behind structures have also been used to provide a recreational and sustainable coastal environment. In this study, the comprehensive XBeach model was used to numerically simulate the evolution of wave transformation, nearshore current, and morphological changes in tombolo planforms behind detached breakwaters. Given various gap spacings between consecutive breakwaters, the numerical results indicated that both equilibrium bay-shaped shorelines and bottom profiles form in the lee of detached breakwaters after long-term persistent wave action. These equilibrium shorelines and bottom profiles were verified using well-known empirical formulas. Post-wave-action retreat displacement to the initial shoreline was analyzed, and an empirical relationship was proposed for predicting the equilibrium bay-shaped shoreline. By associating the empirical formula with a parabolic bay-shape equation, some actual beaches were evaluated to validate the predictions of equilibrium shorelines behind detached breakwaters. In conclusion, to appropriately plan the layouts of breakwaters, bay-shaped shorelines of tombolo planforms in the lee of detached breakwaters can be predicted at the design stage by using the proposed relationship.
... Third, LTC -Long-Term Configuration software [9,10] was properly calibrated with local hydrodynamic and topo-bathymetric conditions and validated with historical data. This software allowed to forecast the evolution of the shoreline over time, for each scenario (i.e., "do nothing" and "breakwater deployment"), relevant for the calculations of eroded areas. ...
Vagueira is a Portuguese village located on the northwest coast of the country. The waterfront of the coastal settlement hosts relevant economic activities and the beach is well visited by tourists, hence concerning a diversity of assets of interest to protect. Nevertheless, it has been affected by a persistent trend of erosion, due to the prevailing deficit of coastal sediments in the littoral drift, and experienced overtopping and flooding events in
the past. Consequently, the inefficiency of existing coastal defences (a longitudinal revetment along the waterfront and a groin located on its downdrift limit) to mitigate coastal hazards is
being discussed.
The objective of this study is to determine if the deployment of a detached breakwater in front of Vagueira beach would help protect the coastal community and safeguard its natural services and general assets. For this purpose, elements at risk were assembled into uniform Land Use and Land Cover (LULC) classes, following the classification adopted in the COS2018 Portuguese map. The numerical modelling of the case study was made using the LTC shoreline evolution model, considering local hydrodynamic and topo-bathymetric conditions and historical sets of data. Thereafter, the LULC map was
overlapped with LTC projections, in a GIS-based environment, to determine the future exposure to coastal erosion and flooding considering the situation of “do nothing” versus the breakwater deployment.
Results demonstrate that the construction of the breakwater can have a global
positive performance, with benefits from halting land losses, increasing the emerged beach
area and reducing flood risk. However, it is not a “one-size-fits-all” solution. Despite several
configurations have been tested, the salient does not cover the whole extension of the
waterfront and there is a negative impact on some LULC classes.
... No presente trabalho, desenvolvido no âmbito do "Estudo de Viabilidade de Transposição Aluvionar das Barras de Aveiro e da Figueira da Foz", aplicou-se o modelo numérico de evolução da posição da linha de costa LTC (Coelho, 2005), para avaliar o desempenho físico (impacto na evolução da posição da linha de costa) de soluções de transposição de sedimentos a 30 anos (2050). As soluções avaliadas contemplaram sistemas de by-pass e alimentações artificiais de sedimentos, com dragagem a Norte das barras e deposição a Sul, tendo-se estudado diferentes parâmetros que condicionam o desempenho e longevidade das soluções: volume transposto, localização e número de saídas, para o sistema by-pass; volume, local de deposição e frequência das intervenções, para as alimentações artificiais. ...
Os setores costeiros Barra-Vagueira e Figueira da Foz-Leirosa, do litoral Oeste português, apresentam recuo generalizado da posição da linha de costa. A retenção de sedimentos a barlamar das estruturas portuárias, que definem a fronteira Norte dos setores costeiros, é apontada como uma das causas para o défice sedimentar e consequente recuo da posição da linha de costa, levando a que se equacionem soluções de transposição de sedimentos através das barras portuárias, com o objetivo de aproximar a dinâmica sedimentar à natural deriva que ocorre no litoral. No presente trabalho, desenvolvido no âmbito do "Estudo de Viabilidade de Transposição Aluvionar das Barras de Aveiro e da Figueira da Foz", aplicou-se o modelo numérico de evolução da posição da linha de costa LTC (Coelho, 2005), para avaliar o desempenho físico (impacto na evolução da posição da linha de costa) de soluções de transposição de sedimentos a 30 anos (2050). As soluções avaliadas contemplaram sistemas de bypass e alimentações artificiais de sedimentos, com dragagem a Norte das barras e deposição a Sul, tendo-se estudado diferentes parâmetros que condicionam o desempenho e longevidade das soluções: volume transposto, localização e número de saídas, para o sistema bypass ; volume, local de deposição e frequência das intervenções, para as alimentações artificiais. Os resultados demonstram que se não forem adotadas medidas para mitigar a erosão costeira, a linha de costa continuará a recuar, levando a perdas de território de cerca de 40 ha no setor Barra-Vagueira e 42 ha no setor Figueira da Foz-Leirosa, em 2050 (Figura 1). As soluções de transposição permitem mitigar os problemas de erosão, sendo os sistemas de bypass as soluções com maior capacidade de contrariar o recuo da linha de costa. Contudo, os impactos são distintos nos dois setores costeiros. Na Figueira da Foz a transposição anual de 1x10 6 m 3 de sedimentos permite anular o efeito erosivo, mas em Aveiro a transposição do mesmo volume não anula o efeito erosivo entre a Barra e a Vagueira. Esta diferença é atribuída em parte ao caudal sedimentar longilitoral que se concluiu ser mais intenso em Aveiro.
... En este sentido, como lo afirma Acosta (2005), la idea del riesgo pensado desde el colectivo social "Se relaciona con una construcción de pensamiento humano, siendo un resultado social y distinto de acuerdo con los contextos experimentados por individuos o grupos, que generan múltiples interpretaciones del evento". A su vez, esta imagen del riesgo que tiene un determinado grupo social, puede ser un instrumento útil para las instancias de protección civil y entidades relacionadas con la seguridad en sus procesos de toma de decisión y acción (Coelho, 2005). Así, la percepción es un producto en que interviene la variedad de características de la personalidad y de la conformación histórica de los individuos en relación con un determinado contexto ambiental, económico, político, social o cultural donde se plasma toda la vida humana. ...
Introducción Ante las condiciones de riesgo socio-naturales, en parte, definidas por la geografía de territorio, las campañas de medios se han visto como una herramienta inmediata para reducir la vulnerabilidad en la población. Ante eventos asociados al cambio climático, que amenazan ser más intensos y de mayor frecuencia, surge la construcción social del riesgo, de acuerdo con Trelles y Donoso (2017) "estas circunstancias se ven agravadas por la pobreza y factores estructurales que pueden incrementar la vulnerabilidad y la exposición de las personas frente a una amenaza", en donde dicha amenaza puede ser del tipo natural o humana.
... The present study aims to assess the impact of artificial nourishments performed south of the Aveiro harbour inlet and sand bypassing systems at the inlet on the morphological evolution of the stretch Barra-Vagueira, considering their performance and longevity. The study was performed through the application of the numerical models LTC -Long Term Configuration (Coelho, 2005), to simulate the shoreline evolution, and CS -Model (Larson et al., 2016), to simulate the cross-shore profile evolution, both in a 30 years perspective. ...
... They change the flow regime of rivers, with consequences on the amount of sediments reaching the littoral. Dams act as a barrier that decrease the river flow velocity, weaken the rivers' sediment transport capacity and consequently trap sediments in updrift areas of the reservoirs (Chen 2005, Coelho 2005, Coelho et al. 2009). However, the negative impacts of dams in the river's sediment transport rate can be mitigated through measures to reduce and control silting in reservoirs, which includes techniques to reduce affluent sediments and their deposition, plus techniques to remove those already deposited. ...
Many shorelines have been retreating at sandy coasts worldwide (Luijendijk et al. 2018), in a redistribution process of sediments resulting from the relationship between sediment availability in the coastal system and their transport capacity by natural hydrodynamic forces (waves, tides and currents). This process is considered a problem, as it endangers activities, infrastructures and human development along the coast. Problems with coastal erosion are complex and their worsening tendency generates frequent criticism among the populations, for whom immediate solutions are necessary. However, coastal erosion mitigation demands effective strategies, planned in long-term perspectives, supported by the identification of risk areas and by cost-effective and cost-benefit analyses. The definition of risk areas allows establishing priorities, in which human occupation can be considered (or should be) forbidden. Costeffective and cost-benefit analyses may also help decisionmakers, showing what is best in a longer perspective, by comparing the costs of the strategies with their physical and economical behavior. To better delineate the strategies to mitigate coastal erosion, an adequate understanding of the causes and consequences of this phenomenon is required, all the physical, environmental, social and economic processes, plus impacts resulting from each intervention or strategic scenario that can be adopted.
... At Vagueira, the beach is both confined by one revetment and one groyne. The reader is referred to [23] for a more in-depth characterization of the study area. ...
In Aveiro (NW coast of Portugal), a coastal monitoring programme was carried out in sequence of a shoreface nourishment intervention (over than 2 M m3) performed in 2020. In this programme, almost one year of biweekly subaerial topographies and quarterly bathymetric surveys have been collected along a 10 km coastal stretch between June 2020 and June 2021. In this study, topographic and bathymetric surveys were analysed to assess the expectation that if the shoreface nourishment is located in sufficiently shallow water depths, its landward movement will feed adjacent beaches and, consequently, increase the subaerial beach volume. Results show that the subaerial beach volume is well correlated with the 1.05 m (above MSL) isoline displacement through time. While the seaward limit of the shoreface nourishment moved landwards about 200 m, the shoreline proxy (isoline of 1.05 m) displayed a maximum seaward displacement of 60 m. The displacement of the shoreline proxy was highly variable in space, along the 10 km coastal stretch, and also in time, during storm events. During such events, both landward and seawards displacement of the shoreline proxy took place, depending on the spatial position. Moreover, while beaches close to the initial shoreface nourishment intervention displayed faster accretion patterns than those located farther away, the well-defined onshore movement of the shoreface nourishment did not result in a considerable beach volume increase. The achieved results were also compared against case studies of shoreface nourishments with similar volumes performed worldwide.
... As construções sobre os sistemas dunares diminuem as proteções naturais e aumentam os níveis de risco de exposição. A destruição dos sistemas dunares leva a uma redução de sedimentos no sistema, diminuindo a capacidade natural das defesas costeiras durante os eventos de tempestades, resultando em galgamentos e inundações mais prováveis, danos e destruição de zonas edificadas ou áreas marginais (Coelho, 2005). ...
O projeto INCCA (Adaptação Integrada às Alterações Climáticas para Comunidades Resilientes) tem por objetivo promover uma abordagem que integre a adaptação às alterações climáticas e a mitigação da erosão costeira em perspetivas de curto, médio e longo-prazo. A adaptação e mitigação deve considerar as dimensões social, ambiental, económica e de engenharia, para ajudar os órgãos de decisão a conceber planos de ação para implementação de estratégias de adaptação às alterações climáticas sustentáveis e duradouras. É um projeto com uma componente participativa, que pretende envolver as populações locais e stakeholders através da realização de workshops de forma a desenvolver um modelo participativo e económico, reduzindo a vulnerabilidade dos territórios costeiros e aumentando a resiliência das comunidades locais. Este trabalho apresenta uma componente do projeto INCCA, cujo objetivo inicial corresponde ao desenvolvimento de um manual de medidas de mitigação e adaptação à erosão costeira e às alterações climáticas, de aplicação transversal a todas as zonas costeiras de características arenosas sedimentares. Esta compilação, identificação e caracterização de medidas é um processo dinâmico, que no âmbito do projeto INCCA, conta com o envolvimento das comunidades locais e stakeholders, através da realização de workshops participativos realizados no concelho de Ovar (caso de estudo do projeto) e apresenta neste momento 53 medidas. A listagem das medidas de mitigação e adaptação à erosão costeira e às alterações climáticas, bem como, cada uma das 53 fichas individuais já construídas, estão disponíveis online (http://incca.web.ua.pt/) e podem ser consultadas e comentadas. Palavras-chave: INCCA; COAST; workshops participativos; impactos; análise custo-benefício.
... Weighted Analytic Hierarchy Process methodology (AHP) for the classification of vulnerability, exposure, and risk of sea action, with the aim of delimiting risk areas. It does not take into account several important variables for the study of coastal risk, such as: historical data on overtopping and flooding; existing species and ecosystems on the coast; existing cultural heritage; wave period and frequency of sea actions [13,41]. ...
Coastal areas are densely populated areas, and they have been experiencing increasing pressures as a consequence of population growth, but also because of climate change aggravation. For this reason, hazard, vulnerability, and risk indexes have been becoming more recurrent, especially to study and analyze low-lying coastal areas. This study presents an analysis on wave overtopping and coastal flooding, using an Analytic Hierarchy Process (AHP) multicriteria methodology, in Costa da Caparica (Portugal). The definition of the different criteria, as well as their respective weighting for the overall problem and index calculation, was carried out with the help of experts in the subject. By following this methodology, and by using Geographic Information Systems (GIS), hazard, vulnerability, and risk indexes were obtained. The most hazardous areas are located closest to the sea, where the elevation is the lowest, whereas the most vulnerable areas are in neighborhoods with specific socioeconomic characteristics (high urban and economic density). Overall, around 30% of the study area displays moderate to very high risk regarding the occurrence of overtopping and flooding events. The results of this study will be helpful in decision-making processes in matters of coastal zone management and monitoring.
Overtopping phenomena and consequent floods cause significant damage to coastal communities. Morphological changes in front of structures during storms can influence their functionality, affecting their stability and leading to failures, impacting the population that are depending on those coastal interventions for their protection. The effect of climate changes, such as sea level rise and increase of the frequency and intensity of storms, can raise the number of overtopping events over defense structures, also increasing coastal morphological changes, challenging future managers, engineers and the scientific coastal communities. A review of morphological changes in front of coastal defense structures and in natural barriers due to overtopping, wave run-down and reflux was conducted. The objective of this review was to find and gather relevant information, sometimes dispersing, reflecting and grouping the concepts found in the literature. Additionally, the gaps in scientific research are addressed, focusing on topics that may be enhanced. Several keywords used in the research were presented, emphasizing the relationship between overtopping and models (physical and numerical), storms, defense structures and morphological changes, also related to wave run-down during storms. The results show that there is limited information available that is mainly related to morphological changes in front of coastal defense structures during storm events, showing an opportunity to develop knowledge.
As the maintenance of ecosystems, the well-being of populations and the economic viability of many commercial activities in coastal zones depend on the balanced and sustainable management of these areas, a cost-benefit analysis was performed to assess the feasibility of constructing a detached breakwater for coastal protection at Vagueira, in Central Portugal. The Vagueira waterfront has been affected by coastal erosion, overtopping and flooding events in the past, so the existing coastal defences are not completely successful in mitigating those phenomena alone. Previous hydraulic and structural tests performed in numerical models, regarding requirements for overtopping and flooding reduction and increment of the beach area, have shown that a detached breakwater, submerged and parallel to the coast, can help meet those targets. Out of the several configurations considered based on length (L) and distance to the shoreline (D), four final options were selected for further examination: L300D400 (best technical solution), L350D400 (second-best solution) and L200D200 and L350D580 (which are two extreme options regarding dimensions of the work and its detachment to the shoreline).
A praia da Vagueira, tal como diversas zonas costeiras em Portugal, tem sofrido o recuo da linha de costa com o consequente aumento dos riscos de erosão e galgamento/inundação (ver Figura 1). Neste sentido, pretendeu-se avaliar o custo-benefício de uma solução específica de intervenção que idealiza a implantação de um quebra-mar destacado (QMD) em frente ao aglomerado urbano da praia da Vagueira. Para tal, discutiram-se 4 opções de configuração do QMD, previamente selecionadas de um conjunto mais vasto, após apreciação do desempenho quanto ao galgamento, à dinâmica sedimentar e à evolução morfológica adjacente. As opções selecionadas variam o comprimento da estrutura (c) e a distância à linha de costa (d), numa combinação de 4 cenários designados c300d400 (melhor solução técnica), c350d400 (segunda melhor solução) e c200d200 e c350d580 (que constituem 2 opções extremas quanto à dimensão da obra e afastamento à linha de costa e que representam, respetivamente, o menor e maior custo de construção).
Cruise tourism is expanding almost everywhere, despite the pandemic generated by COVID-19 in this sector as well. According to estimates and reported by the CLIA (2021), between mid-March and September 2020, the economic damage was around 77 billion dollars, with a loss of jobs that exceed 500 000. The CLIA itself, however, records a significant increase in travelers who aspire to join a cruise, even among those who have never been there. Cruise ships and their economic impact have been the subject of research for many years and the data, which can also be obtained from various agencies and shipping companies, denote the importance of this particular sector, in the more general context of tourism. It is therefore increasingly appropriate to direct research towards an interdisciplinary and multidisciplinary analysis that considers the concept of environmental impact (now in many cases somewhat emptied of its deep meaning and become a sort of opportunistic slogan), so as to consider, in addition to the economic aspects, also the anthropogeographic ones (both negative and positive). In fact, the opportunity to enrich the technical and organizational changes required by the pandemic with second thoughts that also have a cultural impact, in addition to the usual environmental impact, is a delightful opportunity. Through the MSC case study, this contribution aims to partecipate in the reflection on the theme of sustainability, which is also abused lexically, to look at the possibility of directing cruise tourism towards a new way of introducing Man into the landscape.
Wave overtopping situations, mainly caused by growing coastal erosion processes, directly affect the populations, causing coastal flooding, damages, and losses. Investments required for the construction and maintenance of coastal defence structures are thus expected to increase in the future over social, environmental and economically valuable coastal areas. The high costs incurred through coastal structures lifetime require improved knowledge on their performance, being important to deliver optimal solutions that consider impacts, costs and benefits. XD-Coast model was developed to facilitate pre-design processes of coastal structures and the COAST model was developed to perform subsequent cost-benefits analysis. However, the first version of XD-Coast does not allow forecasting wave overtopping phenomena. Thus, this work aims to improve the understanding of the overtopping impacts by including this valence in the XD-Coast and COAST numerical models, allowing to evaluate the relation between the structure design cost and the consequent costs due to overtopping and flooding hazard in the search for optimized solutions. Throughout this work it will be discussed the design of rocky revetments (slope and crown level) and their construction costs, with the potential benefits of reducing the overtopping and flooding consequences. A real case study on the Portuguese coast (Ovar) is also analysed. Conclusions demonstrate that the overtopping and flooding data recorded by the Portuguese Environment Agency (APA) and the ability to adequately reproduce it by formulations, can represent a step forward in the estimative of coastal overtopping and flooding impacts and to define a correlation between events and related costs.
El desarrollo científico tecnológico moderno ha mostrado la vulnerabilidad de la naturaleza, insospechada antes de que se hiciesen reconocibles los daños causados. Y es esta capacidad de daño sobre la naturaleza la que hace considerar la importancia del saber previo, como principio de cautela frente a las acciones del hombre El presente trabajo tiene como objetivo profundizar en las particularidades que caracterizan a la educación para la percepción del riesgo de contaminación por el recurso agua y la
situación que al respecto presenta en el municipio de Mella de la provincia Santiago de Cuba, todo lo cual servirá de base para
fundamentar la necesidad de crear una estrategia de comunicación que incida favorablemente en la calidad de vida de la población.
ResearchGate has not been able to resolve any references for this publication.