Francisco Sancho | National Laboratory for Civil Engineering (original) (raw)

Papers by Francisco Sancho

The Proceedings of the Coastal Sediments 2011, 2011

Large-scale physical model tests are ongoing at CIEM wave flume of the Polytechnic University of ... more Large-scale physical model tests are ongoing at CIEM wave flume of the Polytechnic University of Catalonia. This paper presents some aspects of the study aimed to analyze the effect of wave storm events on dune erosion and overwash processes. Two different regimes of storm attack on the sandy beach/dune system are investigated: a collision regime with swash and run-up to the dune face and an overwash regime with wave run-up overtopping the dune crest (Sallenger et al. 2003). Eight run tests are performed with a combination of four irregular wave conditions and two different water depths. Detailed measurements in time and space of profile evolution, hydrodynamics, sediment concentration, overtopping rate and photogrammetric survey are carried out.

Proceedings of SEASAR, 2006

Rip currents are near-shore cellular circulations that can be described as narrow, jet-like and s... more Rip currents are near-shore cellular circulations that can be described as narrow, jet-like and seaward directed flows. These flows originate close to the shoreline and may be a result of alongshore variations in the surface wave field. The onshore mass ...

Este trabalho tem como principal objetivo verificar se diferentes linhas de costa iniciais,<br... more Este trabalho tem como principal objetivo verificar se diferentes linhas de costa iniciais, extraídas de imagens de satélite e de sensores, influenciam os resultados da modelação da sua evolução a longo prazo. Primeiramente, comparam-se as posições da linha de costa, em instantes próximos. Seguidamente, determina-se em que medida a ordem de grandeza da variação inicial observada influencia a evolução da linha de costa, usando o modelo numérico LITMOD. Verifica-se que as imagens de satélite mais indicadas para a extração da linha de costa são as obtidas pelos sensores NIR e RGB (satélite Sentinel2), concluindo-se que a morfologia da praia poderá influenciar a precisão da extração da linha de costa. Ao usar o modelo LITMOD constata-se que a importância dos desvios iniciais na posição da linha de costa se atenua com o tempo de simulação, embora haja um impacte significativo no cálculo de sedimento...

Apresenta-se uma panorâmica geral sobre a protecção da orla costeira. Referem-se os processos fís... more Apresenta-se uma panorâmica geral sobre a protecção da orla costeira. Referem-se os processos físicos responsáveis pela dinâmica sedimentar, e os principais problemas a ela associados que afectam praias e embocaduras de estuários e lagunas. As soluções mais comuns para este tipo de problemas são depois revistas de forma crítica. Finalmente, três casos de estudo são utilizados para exemplificar problemas e soluções, e, simultaneamente, ilustrar abordagens seguidas em estudos de engenharia: uma praia encaixada em erosão (praia de Hac-Sá, República Popular da China), um sistema composto por três praias, um canal e uma laguna com problemas simultâneos de erosão e assoreamento (praias de Leblon, Ipanema e Arpoador, Brasil) e uma embocadura lagunar com problemas de assoreamento e de estabilidade (Lagoa de Óbidos, Portugal).

Natural beaches often present a breaker bar that significantly affect physical phenomena like, fo... more Natural beaches often present a breaker bar that significantly affect physical phenomena like, for example, wave transformation, wave reflexion, energy dissipation due to breaking and wave reforming into the trough region. These transformations are associated to nonlinear wave modifications. In this work the oscillatory flow near the bottom of barred beaches is characterised. To achieve that purpose, the data obtained during two experiments were examined and processed: the data from a large-scale laboratory experiment carried out at the wave flume of the Polytechnic University of Catalonia (Barcelona, Spain) and the data from a nearshore field experiment, denoted by DUCK94, performed in

Ocean & Coastal Management, 2017

Abstract Coastal zones are socially and economically very important, leading to a high pressure f... more Abstract Coastal zones are socially and economically very important, leading to a high pressure for its permanent development. Simultaneously, these zones are subject to several maritime hazards, able to cause coastal erosion. Therefore, a thoughtful management of these zones is required in order to protect society, economy and natural environments. This work presents a GIS-based tool that aims to provide a quick assessment to coastal erosion risk, called CERA: Coastal Erosion Risk Assessment. The simple processes and small amount of data required by the tool provides a viable alternative to other methods, which are often more complex and difficult to apply. The assessment method used in CERA is divided in two parts. The first part is a vulnerability assessment, which combines several parameters that influence coastal erosion, each being classified in a scale of 1–5. The second part, a consequence assessment, follows the same procedure, but considering socio-economic aspects. Then, a risk matrix is applied to determine a risk classification, also divided in 5 classes, from I to V. Aveiro, in Portugal, and Macaneta spit, in Mozambique, were selected to test the application. Data was gathered for both locations. While in Aveiro it was used a considerable amount of available georeferenced data, for the Macaneta spit the data was mainly prevenient from previous publications and local expert knowledge. The results show that both study areas have similar vulnerabilities to coastal erosion, with classes IV and V dominating along the areas closer to the shoreline. On the other hand, the consequence classification in Aveiro is higher than in Macaneta, resulting in a higher risk level in several regions in Aveiro district. The higher level of detail in Aveiro data also resulted in a more even distribution across all class levels in the results.

Geomorphology, 2008

Two years of offshore wave data and daily time exposure images from Trafalgar beach, a 2-km-long ... more Two years of offshore wave data and daily time exposure images from Trafalgar beach, a 2-km-long sandy beach located on the southwest coast of Spain that frequently exhibits rhythmic features, were used to (1) explore the variability of the beachface morphology and (2) determine environmental conditions associated with the different morphological states. The beachface morphology at three distinct alongshore sectors was analyzed and classified and five different morphological states were found that are related with the presence or absence of beach cusps and a berm: (1) large beach cusps, (2) small beach cusps, (3) low-tide terrace; (4) plane beach berm and (5) plane beach. The predominant beachface morphology is characterized by the presence of large beach cusps, and the main wave climate consisted of offshore significant wave heights ranging from 0.5-1 m and wave periods between 4 and 12 s. An alongshore variation of the morphology is found which might be related to the nearshore wave variability (SWAN wave model results). The morphologies are, in some cases, well-correlated with the daily offshore incident wave climate (described by the daily maximum significant wave height and the corresponding period), particularly for the moderate to high energy wave conditions. Small beach cusps appear under short period waves, whereas when the wave periods are longer the morphology tends to change to large beach cusps. This transition only occurs if the forcing is maintained as constant for a certain duration, which depends itself on the wave energy. It is concluded that correlations over 90% are only found for the highest wave energy conditions or under long wave periods. For the remainder, it is not possible to generally correlate the beachface morphology based only on the wave forcing because the previous morphological state cannot be ignored.

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

The bed forms in the surf zone can grow as a result of natural morphodynamic instabilities, force... more The bed forms in the surf zone can grow as a result of natural morphodynamic instabilities, forced by the wave-induced flow. This work gives a contribution to the dynamics of the formation and evolution the bed forms in surf zone. We use the new morphodynamic model, M-SHORECIRC, to analyze the growth and dynamics of bar-type, rhythmic, bed forms of a barred beach. These analyses include the effects of initial wave angle, wave energy, and bar location. These are all seen to influence the dynamics of the rhythmic bed-forms regarding the longshore length-scales, and intensity and location of bed-forms.

Ocean Modelling, 2012

The morphology of estuaries and rivers changes constantly due to the dynamic imbalance between th... more The morphology of estuaries and rivers changes constantly due to the dynamic imbalance between the forcing actions (e.g. river flow, tides, surface waves and wind) and the sedimentary reactions. Understanding and predicting these changes are very important for an scientific-based, sustained management of these systems. Morphodynamic process-based numerical models can be used for this purpose. The development and validation of a new three-dimensional unstructured grid morphodynamic modelling system, MORSELFE, aiming at simulating short-term morphological evolutions of estuaries and sandy rivers (temporal scale of days to month), are presented. MORSELFE couples a three-dimensional hydrodynamic model, with an advection–diffusion transport model for the suspended sediments, an empirical formula for the bed load, and a bed updating module. The model considers the simulation of non-cohesive sediment and does not account for wave effects. A new approach is proposed to compute the erosive f...

ABSTRACT Thesis (Ph. D.)--University of Delaware, 1998. Principal faculty adviser: Ib A. Svendsen... more ABSTRACT Thesis (Ph. D.)--University of Delaware, 1998. Principal faculty adviser: Ib A. Svendsen, Dept. of Civil and Environmental Engineering. Includes bibliographical references (leaves 310-319).

This research provides an overview of the large-scale physical model experiments conducted at the... more This research provides an overview of the large-scale physical model experiments conducted at the Canal d'Investigacio i Esperimentacio Mar‘itima, Laboratori d'Enginyeria Mar‘itima, Universitat Politecnica de Catalunya, Barcelona, within the EU-Hydralab III Integrated Infrastructure Initiative. The model tests have been carried out in a flume with a sandy dune exposed to a combination of water levels and wave conditions. Different regimes of wave attacks on the sandy beach/dune system were investigated. In particular, the study provides a unique set of large-scale physical data concerning the wave-induced dune overwash. Measurements of velocities, sediment concentrations and beach–dune profile evolutions were considered. The profile measurements have been used to calibrate and validate a numerical model predicting the beach–dune profile modifications over the near-shore region. The numerical model compares well with the experimental data.

The Proceedings of the Coastal Sediments 2011, 2011

Proceedings of SEASAR, 2006

Ocean & Coastal Management, 2017

Geomorphology, 2008

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

Ocean Modelling, 2012