Hydrographic Institute

Lisbon, Portugal

Hydrographic Institute

Lisbon, Portugal
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Balsinha M.,Hydrographic Institute | Fernandes C.,Hydrographic Institute | Oliveira A.,Hydrographic Institute | Rodrigues A.,Hydrographic Institute | Taborda R.,University of Lisbon
Journal of Sea Research | Year: 2014

Grain-size trend analysis (GSTA) was used to infer sediment transport patterns on Estremadura Spur continental shelf. Sediment transport patterns were defined using the Gao and Collins (1992) method applied on an extensive collection of superficial sediment samples collected from 14 to 706. m water depths and using a characteristic distance based on geostatistical analysis. Results are in relatively good agreement with known oceanographic drivers for the external shelf (internal waves, and upwelling) and measured near-bottom currents. At the mid and inner shelf computed sediment transport vectors yielded less coherent patterns probably related with low sampling density in relation to surficial sedimentary deposit dimensions and the presence of rocky outcrops. © 2014 Elsevier B.V.

Goncalves D.S.,University of Aveiro | Pinheiro L.M.,University of Aveiro | Silva P.A.,University of Aveiro | Rosa J.,University of Aveiro | And 4 more authors.
Coastal Engineering | Year: 2014

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. © 2014 Elsevier B.V.

Lovrincevic D.,Hydrographic Institute | Kljajic I.,University of Zagreb
Nase More | Year: 2014

In the early 1980s, with the rapid development of geospatial technologies the development of Electronic Navigational Charts – ENC began. With a heavy emphasis on data security, because of its navigational purpose, the implementation of ENC was approached very cautiously. One of the key features of every product, which enables easier global use, is its standardization. The paper provides basic information related to the ENC and by studying all editions of publications for ENC, the reports of the Working groups of the International Hydrographic Organization – IHO and articles that followed the implementation process of ENC standards an overview of ENC standards is given, with the focus on two basic standards published in S-57 and S 52 publications. Also described is a new, currently under construction, standard for ENC (S-100) and the prediction of the future development guidelines with the concept of e-Navigation in mind. © 2014, University of Dubronvnik. All rights reserved.

Rodrigues M.,National Laboratory for Civil Engineering | Guerreiro M.,National Laboratory for Civil Engineering | Guerreiro M.,Hydrographic Institute | David L.M.,National Laboratory for Civil Engineering | And 4 more authors.
Journal of Environmental Engineering (United States) | Year: 2016

The role of environmental forcings on the fecal contamination dynamics in small coastal streams was investigated, using the Aljezur coastal stream (Portugal) as a test case. An integrated modeling approach, combining hydrological and coupled hydrodynamic-fecal indicator bacteria models, was applied to selected scenarios of relevant forcings, on the basis of previously calibrated and validated model applications. The forcings investigated included: tides, winds, waves, atmospheric pressure, bathymetry, river flow, and upstream fecal bacteria concentrations; this study targeted the characterization of the relative importance of these factors on the fecal contamination dynamics, to enhance our understanding of small coastal streams water quality dynamics. Results highlight distinct patterns for dry and wet periods. Fecal bacteria transport is mainly forced by tidal propagation, in dry periods; and by freshwater flows, during wet periods. The analysis reveals a complex hydraulic and water quality dynamic resulting from the interactions between the environmental forcings and strongly dependent on their relative strength. This analysis can be extrapolated for systems with a similar balance between the environmental factors. © 2016 American Society of Civil Engineers.

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