Papers by Sebastião Braz Teixeira
Sedimentological features of tsunami and storm deposits in Almargem (central Algarve)
EGU General Assembly Conference Abstracts, Apr 1, 2019
Morphosedimentary and ecosystem evolution at Belharucas beach after a sand nourishment (Algarve, south Portugal)
<p>Beach nourishment is an increasingly recommended... more <p>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.</p><p>From April 2017 to November 2019, sediment samples and beach profile data were collected seasonally, before and after a sand nourishment (100.000m<sup>3</sup>) that increased 30m of width in Belharucas beach (south Portugal, Algarve).</p><p>The main objective of the work was to evaluate the nourishment impact in the beach ecosystem, aiming at contributing to seafloor integrity assessment, in the scope of Descriptor 6 of the Marine Strategy Framework Directive. </p><p>Methodology included grain size and macrobenthic fauna analyses in two profiles of the nourished area and another one further away, selected as a control area. Each profile was sampled at three intertidal zones: supralittoral (beach berm), mediolittoral (beach face) and infralittoral (low tide terrace).  Beach profile data were collected with the main objective of measuring the beach width and evaluate nourishment longevity.</p><p>Results show that grain size variability, higher at beach face, is dominated by local energy beach conditions rather than to changes related to the nourishment.</p><p>Morphological data shows that beach nourishment had a relatively low longevity as two years after the nourished beach present roughly the same width as priori to nourishment.</p><p>While supralittoral samples were defaunated, medio and infralittoral ones exhibited extremely low diversity. Assemblages were dominated by small-size polychaetes, bivalves and isopods. No statistically significant differences were found in assemblage composition regarding pre- and post-sand nourishment, year seasons, tidal zones and control stations.</p><p>In conclusion, Belharucas beach exhibited high resilience to the sand nourishment, preserving its morphodynamics and ecosystem conditions.</p><p> </p><p>The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and through the strategic project UIDB/MAR/04292/2019 - MARE and ECOEXA project (MAR-01.04.02-FEAMP-0016)</p>
Impacts of sand extraction and deposition on the ecosystem recovery rate in the southern coastal zone of Portugal
<p&amp... more <p>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 still poorly known, contributing to the lack of information needed for the assessment of Descriptor 6 (Sea-floor integrity) of the Marine Strategy Framework Directive (MSFD).</p><p>The aim of this work is to evaluate the morphological and ecosystem impacts of sand extraction at the inner shelf, as well as the consequent impacts of sand deposition at the nourished beaches. In this context, short-term and long-term monitoring activities based on a multidisciplinary approach were implemented at new and former borrow areas located in the southern Portugal (Algarve) inner continental shelf and adjacent beaches. These activities include multibeam bathymetric surveys complemented by surface sediment sampling, wave and current measurements, and a fluorescent tracer-marked sand experiment. Moreover, benthic macrofauna composition and structure are being studied at borrow areas (former and new) and at the nourished beaches. The acquired data allow a first assessment of the recovery rates regarding the sea-bottom morphology and benthic communities, and contribute to a better understanding of the involved processes.</p><p>The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and ECOEXA project (MAR-01.04.02-FEAMP-0016)</p>
Coastal Engineering, Jun 1, 2014
Offshore sand and gravel extraction for aggregates and beach nourishment is an important economic... more Offshore sand and gravel extraction for aggregates and beach nourishment is an important economic activity and has been a common practice in various countries worldwide for many years. The evolution of a sandpit, in particular its migration and rate of replenishment, depends strongly on the type of sediments involved, and on the physical and hydrodynamic characteristics of the surrounding area. In order to fully assess the associated impacts on local ecosystems and on the neighboring coastline morphology it is essential to make accurate predictions of the excavation recovery times. For this purpose it is fundamental to investigate areas where there is an adequate observational control of the evolution of the sandpit, prior and after the excavation, to properly calibrate existing numerical models with observations and fully evaluate their prediction adequacy. The present work investigates the evolution of an offshore sandpit located off Vale do Lobo, Algarve, Portugal, within a time span of four years (2006-2010), based on 4 bathymetric surveys, prior to and after the dredging operations, complemented with the analysis of wave data and numerical modeling simulations. The bathymetric data were used to evaluate the morpho-sedimentary evolution and to calculate the sediment volume changes. The results show an infill of approximately 17% of the initial exploration pit in the first 4 years, with an overall smoothing of the initial excavation bottom topography. Observations combined with modeling results demonstrate that the pit evolution depends mainly on storm events, since it is essentially during these periods that there is a significant sediment movement at the site water depth. Based on (1) the predicted number of stormy days for the forthcoming years, assuming that (2) the yearly average of such events in the past 57 years is representative, and considering (3) a decrease of the sandpit recovery rate in time, predicted by models and observations, it was possible to estimate that the Vale do Lobo sandpit recovery period is of ca. 38 years for its full, or near full, replenishment.
Arqueologia e geodinâmica do litoral: o caso de Quarteira (Algarve, Portugal)
3O Congresso De Arqueologia Peninsular Utad Vila Real Portugal Setembro De 1999 Vol 8 2000 Isbn 972 98807 2 7 Pags 609 622, 2000
Geodinâmica Das Arribas, Ocupação e Risco No Troço Carvoeiro-Algar Seco (Lagoa, Algarve)
SlopeMassMovments Inventory 2020 21 Barlavento Coast 1Jul2021
Intervenções executadas em 2009/2010 visando minorar o risco associado à geodinâmica das arribas do litoral do Algarve
Slope mass movements field inventory 2014/15. Rocky sea cliffs, Barlavento Coast (Algarve, Portugal)
Síntese Dos Trabalhos De Caracterização Da Reserva Ecológica Nacional Submarina Do Algarve Central
Slope mass movements field inventory 2017/18. Rocky sea cliffs Barlavento Coast (Algarve-Portugal)
Slope mass movements field inventory 2016/17. Rocky sea cliffs Barlavento Coast (Algarve-Portugal)
Prospecção de manchas de empréstimo ao largo de Albufeira (Algarve)
Inventory of slope mass movments on rocky sea cliffs 2019/20
Agravamento do risco associado à erosão costeira no troço do litoral entre Forte Novo e Garrão (Loulé), Algarve, Portugal
Submarine Evidences of Holocene Shoreline Migration on Quarteira Coast (Southern Algarve-Portugal)
Dinâmica morfossedimentar da Ria de Aveiro (Portugal)
Slope mass movements field inventory 2018/2019. Rocky sea cliffs. Barlavento Coast (Algarve)
Slope mass movements field inventory 2015/16. Rocky sea cliffs Barlavento Coast (Algarve-Portugal)
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Papers by Sebastião Braz Teixeira