João Cascalho

• PhD
• Research Assistant at University of Lisbon

The in situ measurement of sediment transport in wave-dominated environments presents significant challenges and currently often relies upon the use of fluorescent sediment tracers. However, this method is constrained by challenges in conducting unbiased and representative sampling, as well as facing overall logistical complexities and labour-inten...

Commercially available, daylight and near-ultraviolet fluorescent, colored dyes can be used in long-or short-lived surface coatings on coarse sediments. Such tracer coatings make possible day-or nighttime visual and quantitative determination of river or beach sediment transport (Yasso, W.E., 1966. Formulation and use of fluorescent tracer coatings...

The main objective of this work is to assess the sediment dynamics at the inner shelf in the vicinity of the depth of closure (DoC). The present work was developed within the scope of ECOEXA project that aims to characterize the impact of sediment extraction on marine ecosystems and, at the same time, assess the respective recovery rate.

This report contains the description of my research activities between 2016 and 2019.

Beach nourishment is an increasingly recommended solution for reversing the erosion process that affects nowadays the coastal zone. Usually, it is used in emergency situations as a local and short-term solution or as a regional and long-term management strategy. From April 2017 to November 2019, sediment samples and beach profile data were collecte...

The continuous need for beach nourishment requires a detailed understanding of the sediment transport characteristics at the shelf borrow sites, to assess their recovery rate and to evaluate the long-term sustainability of these operations. The main objective of this work is to assess sediment transport conditions at an inner shelf borrow site expl...

Heavy minerals are typically rare but important components of siliciclastic sediments and rocks. Their abundance, proportions, and variability carry valuable information on source rocks, climatic, environmental and transport conditions between source to sink, and diagenetic processes. They are important for practical purposes such as prospecting fo...

Artificial nourishment of sandy beaches using sediment from borrow areas located on the continental shelf is increasingly a recommended solution for reversing the erosion process that affects the coastal zone. However, the impact of sand extraction in the shelf and deposition on the beach on the benthic communities (structure and functioning) is st...

In October 2012, Hurricane Sandy caused severe erosion on beaches and dunes of Fire Island (New York, USA). Major shoreline changes occurred with erosional dominance in the upper shoreline and aggradation in the lowermost section of the beach due to the deposition of eroded upper-beach and dune sediment. Sand laminae with a high concentration of he...

Resumo O projeto "Caracterização do impacte da extração de areias e avaliação da taxa de recuperação do ecossistema-ECOEXA" tem por objetivo estudar o impacto associado à extração de areia em manchas de empréstimo de sedimento, destinadas à alimentação artificial de praias, na integridade do fundo marinho. A monitorização servirá para estudar a evo...

This work describes and interprets the presence of heavy minerals in the WNW Portuguese continental margin using a set of 78 bottom samples collected from three distinct areas of this margin: the Porto, Aveiro, and Nazaré canyon head areas. The main transparent heavy mineral assemblage (mineral grains with frequencies ≥1% identified under a petrogr...

This work describes and interprets the presence of heavy minerals in the western Portuguese continental margin using a set of 78 bottom samples collected from 3 distinct areas of this margin: Porto, Aveiro and Nazaré canyon head areas. The main transparent heavy mineral suite (minerals with frequencies >10%), is composed by amphiboles (hornblende),...

The fluvio‑estuarine beaches of downtown Lisbon during the Iron Age and Roman Period. In the aim of the Lisbon Stories project several sediment samples, both sediment cores and discrete samples, were recovered in the riverine Lisbon area. The analyses of those sediments will allow rebuilding the palaeoenvironmental evolution of the northern Tagus m...

Recent work has applied microtextural and heavy mineral analyses to sandy storm and tsunami deposits from Portugal, Scotland, Indonesia and the USA. We looked at the interpretation of microtextural imagery (scanning electron microscopy) of quartz grains and heavy mineral compositions. We consider inundation events of different chronologies and sour...

The understanding of the sedimentary links between the beach and the continental shelf is crucial for the evaluation of the coastal sediment budget. However, the comprehension of this dynamics is still poorly understood owing greatly to the lack of direct sediment transport measurement at seasonal and longer time scales. This work aims at evaluatin...

Characterization of heavy mineral (HM) assemblages in tsunami deposits has been applied to infer inundation and backwash phases and to establish sediment sources. In ideal conditions and due to their specific density (>2.9 g/cm3), heavy minerals are the most suitable component of a sediment assemblage that can provide information regarding flow com...

Resumo: O areal da Praia Grande apresenta frequentemente uma areia escura que se associa à elevada concentração em minerais pesados. Neste trabalho pretende-se caracterizar este fenómeno e compreender as razões associadas a esta concentração. Para cumprir este objectivo foi analisado um conjunto de amostras de sedimento recolhidas na Praia Grande e...

O areal da Praia Grande apresenta frequentemente uma areia escura que se associa à elevada concentração em minerais pesados. Neste trabalho pretende-se caracterizar este fenómeno e compreender as razões associadas a esta concentração. Para cumprir este objectivo foi analisado um conjunto de amostras de sedimento recolhidas na Praia Grande e em prai...

Grande beach's sand often presents a dark color due to the abundant presence of heavy minerals. This work aim to understand this phenomenon based on the analysis of heavy mineral distribution along Grande beach and adjacent beaches located in the same sedimentary littoral cell (São Lourenço, Foz do Lizandro, Maçãs, Pequena, Adraga, Abano and Guinch...

At Grande beach it is common observe the presence of blackish sand (heavy mineral placer) that makes a contrast with the predominant white sand that characterize the nearby beaches. This study aims to understand the presence of such blackish sand using the mineralogical composition of the Grand beach and 7 nearby beaches was studied. At Grande beac...

A plataforma continental desempenha um papel fundamental na dinâmica sedimentar costeira ao fazer a ligação entre a praia e o domínio oceânico. Este trabalho tem por objetivo estudar a dinâmica sedimentar deste ambiente ainda pouco conhecido. Nesse sentido, foi realizada uma experiência com areias marcadas ao largo de Tavira, que envolveu a injeção...

This study applies heavy mineral analysis to the Storegga tsunami deposit across a range of locations (Whale Firth, Maggie's Kettle Loch and Scatsta Voe) in Shetland (Scotland). The usefulness of this proxy is tested in the identification and characterization of these palaeotsunami units. Furthermore, provenance relationships are established based...

Sand spits are important coastline features in western Angola, but only limited knowledge on their recent evolution and sediment sources were obtained so far. The present study is focused on the Baía Farta and Lobito sand spits of coastal Benguela that develop to the north (i.e. downdrift) of the Coporolo and Catumbela river outlets. We used grain-...

The sand from Grande Beach (Sintra, Portugal) often presents a dark color due to high concentration in heavy minerals. This work pretends to characterize this phenomenon as well as to explain what causes it. To fulfill this objective, it was collected a sample set from Grande Beach and other beaches of the same sedimentary littoral cell (São Louren...

The aim of this study is to discuss and to extend the characterization of (palaeo)tsunami deposits, and their source materials, based upon the detailed study of their heavy mineral assemblages. Results obtained from three distinct locations (Portugal, Scotland and Indonesia), different coastal contexts and chronologies (the tsunami events studied t...

The sedimentological record provides a database useful to characterize and evaluate recurrence of tsunamis and storms, which contributes to assess the vulnerability of coastal areas to these natural hazards. Thus, the enhancement of our ability to recognize specific signatures of tsunami and storms in coastal sediments is of unquestionable interest...

Resumo: O presente trabalho baseia-se no estudo de mais de 100 amostras de sedimentos oriun-das de três áreas do sudoeste da Península Ibérica: i) área envolvente do Cabo de Sines (plataforma interna), ii) rio Guadiana e plataforma interna adjacente à sua foz e iii) plataforma média do Golfo de Cádiz. A partir destas amostras foram feitas preparaçõ...

This work aims to characterize and understand the textural selection process related to headland sediment bypassing at three adjacent beaches (Norte, Prainha and Nazaré) located at the west coast of Portugal. To characterize sediment median grain size variability across the study site, 72 samples were collected and photographed with a digital singl...

Efetua-se a caraterização geoquímica e mineralógica dose sedimentos recolhidos com um core de gravidade em dois locais: crista da ilha Terceira e monte submarino Great Meteor (cruzeiro EMEPC G3/2007). Os dois testemunhos verticais de sedimentos são descritos tendo em atenção a granulometria das partículas, o conteúdo em carbono orgânico e inorgânic...

Today, scientific literacy has become increasingly important as a hallmark of citizenship and as a way to facilitate many of life's daily decisions. Scientific literacy can be achieved through learning, a complex lifelong process that occurs both in school and out-of-school settings. As most adults only engage in formal education about science duri...

Forthy eight surface sediment samples were collected in April and July 2002 in the Minho and Coura estuaries, where pronounced daily changes in environment conditions were found. The samples included bottom estuary and tidal marsh deposits in order to characterize the benthic foraminiferal zonation. A total of 34 calcareous and 28 agglutinated spec...

The longshore sediment transport is one of the most determinant processes in the evolution of littoral spits and therefore its estimates has a very important role in the study of these coastal landforms evolution and forecast. The aim of this work is to compare the longshore drift estimated by three independent methods (coastline evolution, energy...

The Beach Sand Code project (BSC) aimed to place the sediments at the center of beach morphodynamics research. BSC project made relevant advances over the current state-of-art in several key research topics, namely in the understanding of beach sediment textural variability and in grain size effects on sediment transport. These results prove that t...

N atural History museums are institu-tions devoted to scientific research, collections management, science education and scientific dissemi-nation. As such they are important places for non-formal education and science public outreach. When planning for any sort of ac-tivity Museu Nacional de História Natural e da Ciência (MNHNC) aims to provide re...

Sediment grain size variability is fundamental to understand the processes and direction of sediment transport on littoral systems. The aim of this work is the characterization of the grain size variability and the implications on the definition of adequate sampling strategies. The work was developed at Norte beach, a high energetic and heterometri...

Longshore sediment plays a major role in coastal evolution; however its quantification still rely on empirical formulas calibrated with disparate field techniques. This work aims to evaluate and compare the longshore drift estimated by empirical formulations and experimental predictors. In order to achieve this objective it was carried out a field...

In order to characterize the beach active layer textural variability, an innovative application of sand digital image analysis was successfully developed and applied at two Portuguese beaches. This method, based on digital image analysis techniques coupled with an acquisition device specially developed for this type of application, allowed the char...

Presently, conceptual and numerical sediment concentration modelling is largely based on the diffusion approach. However, several works have shown that this approach is, frequently, unsuitable to model the profile distribution of different grain size particles in the same flow. In order to understand the grain size effects on suspended sediment con...

This study addresses to the evaluation of the suspended sediment concentration in a fetch limited beach (Alfeite Beach) using optical backscatter sensors (OBS) appraising, simultaneously, sensor response to the physical characteristics of suspended particles. In order to achieve these objectives two OBS sensors, deployed at the intertidal zone of A...

The study of heavy minerals from of 21 samples, collected at the continental shelf and littoral stretch of Nazaré, was made in order to get further insights on the hydraulic behaviour of these minerals. Based on mean grain-size differences between sediment and heavy minerals, of normal distributed samples, it was possible to differentiate settling...

Knowledge of the transparent heavy minerals present in the sand fraction of sediments on the northern Portuguese continental margin rests on the study of 504 samples, obtained from the shelf and upper slope (358), and from the major rivers (146). Results show the main association comprising biotite, andalusite, tourmaline, amphibole, garnet, stauro...

A fluorescent sand-tracer experiment was performed at Comporta Beach (Portugal) with the aim of acquiring longshore sediment transport data on a reflective beach, the optimization of field and laboratory tracer procedures and the improvement of the conceptual model used to support tracer data interpretation.The field experiment was performed on a m...

This paper presents a multi-proxy study of sediment samples from the area of the northern Gulf of Cadiz Shelf (SW Iberia) influenced by the Guadiana River. 471 surface sediment samples from the northern gulf of Cadiz Shelf from January 1999 to November 2003 are analysed for grain size variations and composition, including a series of samples retrie...

In order to investigate the sedimentary dynamics of the Madeira's southern shelf several aspects of this North Atlantic island shelf were studied. The principal goals of this work are: identification of the major sediment sources to the shelf; understand the sedimentary patterns and obtain further insight into the governing mechanisms of the shelf....

The main objective of this work is to investigate intra-tidal morphology changes during a tidal cycle and understand their relationship with the geometry of the sand mixing depth layer. To accomplish this objective high resolution elevation changes and mixing depth levels were monitored in a cross-shore profile. From analysis of the detailed beach...

The relative abundance of the different heavy mineral species may be used as a tool to deduce the provenance signal of the sediment and the dominant transport mode that occurred just prior to sedimentation. In this work, the sedimentary infilling of the Douro estuary was analysed using Principal Components Analysis (PCA) in order to characterize th...

Since June 2001 Faro beach (Algarve, Portugal) has been studied in the scope of a scientific project that aims the study of cross-shore processes. During several field experiments, sand layers rich in heavy minerals were observed in the beach face. The presence of these layers at beach face is generally accepted as a consequence of a marked erosion...

The main objective of this paper is the use of heavy minerals assemblages in the study of coastal dynamic processes. The study was carried out in a peculiar sector of the Portuguese coast, where an exotic intrusive sub-volcanic complex makes a distinct contrast in the Southwest Portuguese coastal area (Paleozoic formations). To achieve this objecti...

Forthy eight surface sediment samples were collected in April and July 2002 in the Minho and Coura estuaries, where pronounced daily changes in environment conditions were found. The samples included bottom estuary and tidal marsh deposits in order to characterize the benthic foraminiferal zonation. A total of 34 calcareous and 28 agglutinated spec...

The multidisciplinary study (sedimentology: texture, carbonates, organic matter, elemental composition, mineralogy of sand and clay; micropaleontology: foraminifera, calcareous nannoplankton and pollen -and radiocarbon dating) of three cores recovered from the Douro estuary infill has allowed to reconstruct the paleoenvironmental guidelines of this...

This work focuses on the study of 90 heavy mineral samples from three different sand size classes (medium, fine and very fine sand) of three cores collected from the Douro estuary. These cores were obtained by rotary drilling. For each sample the heavy minerals were counted and twelve major non opaque species were identified. Studying the relative...

RESUMO Palavras-chave: foraminíferos bênticos; Actual; salinidade; estuário Minho/Coura; Portugal. O estudo da evolução do estuário do rio Minho, desde o Último Máximo Glaciário, (projecto ENVICHANGES-FCT) iniciou-se pela análise das associações de Foraminíferos bênticos actuais, para apoiar a posterior interpretação de sondagens. A realização de p...

On the basis of sedimentological and oceanographical data, a transport scheme for fine-grained material is proposed in order to explain the location of a muddy deposit present in the northern Portuguese continental shelf, north-west off the Douro River mouth. This mid-shelf deposit is recent, active and its main source is apparently the Douro River...