Rui Capitão

Wave hydrodynamics around a multi-functional artificial reef at Leirosa

This paper describes an application of the Boussinesq-type COULWAVE model to study the wave hydrodynamics in the vicinity of a multi-functional artificial reef (MFAR). This reef is under investigation and consists of a supplementary protection solution for the Leirosa sand dune system located at South of Figueira da Foz, on the Portuguese West coast. Such installation near the coastline is expected to contribute to enhance the surfing conditions in the area, protect the sand dune system in the surroundings of Leirosa beach, and increase its environmental value. Numerical calculations with the COULWAVE model were performed for four test cases, considering two reef geometries (differing in the reef angle) and two incident wave conditions (storm condition and a common wave condition). Comparisons between the results obtained, in terms of wave heights and breaking line positions allow us to assess the influence of the reef on the hydrodynamics near the beach and around the reef. Moreover, the reef performance was analysed in terms of surfability and coastal protection. The surfability parameters (breaker height, Iribarren number and peel angle) were calculated for each test case using the numerical wave heights, wave directions and wave breaking positions. Comparisons of parameters allow characterizing the most appropriate configuration of the reef to improve the surfing conditions in the study area. A methodology based on numerical free surface elevations and horizontal velocity components was developed to calculate wave directions, since this is not a direct output of the COULWAVE model. Concerning coastal protection, analyses of the mean currents around the reef were used together with observations of the velocity cells near the shoreline as an indication of the sediment transport.

Preliminary phases of the HIDRALERTA system: Assessment of the flood levels at S. João da Caparica beach, Portugal

ABSTRACT Raposeiro, P.D., Fortes, C.J.E.M., Capitão, R., Reis, M.T., Ferreira, J.C., Pereira, M.T.S., Guerreiro, J., 2013. Preliminary phases of the HIDRALERTA system: Assessment of the flood levels at S. João da Caparica beach, Portugal. The length of the Portuguese coast, the severity of the sea conditions and the concentration of population and economic activities on its coastal zone justify the importance of studying wave-induced risks and, in particular, flooding due to wave action. Indeed, emergency situations caused by adverse sea conditions are frequent and put in danger the safety of people and goods, with negative impacts for society, economy and natural heritage. So, assessing the risk of flooding of coastal and port areas is essential for the proper planning and management of these areas. In this framework, a methodology for the flood risk assessment in coastal and port areas is under development. The methodology is embedded into the HIDRALERTA system, a novel integrated system for port and coastal management, designed to prevent emergency situations, to support their management and to forecast incidental long-term interventions. The present paper describes the methodology, the HIDRALERTA system and a case study, the São João da Caparica beach, on the Lisbons area, where the referred methodology was recently applied. Sea wave characterization and flood level calculations are presented for the study.

Hydrodynamics around an Artificial Surfing Reef at Leirosa, Portugal

As a new alternative countermeasure to protect the coastal zone and to increase the surfing possibilities in the Leirosa area of Portugal, multifunctional artificial reefs were investigated numerically in this paper. The primary surfing parameters used in the design (i.e., breaker type, peel angle, wave height at breaking, and currents around the artificial reef) were analyzed. The reef functionality was also analyzed for coastal protection. Two reef geometries with different reef angles of 45 and 66° were tested, considering two design wave conditions (storm and common) and two tide levels (medium and low). Simulations show that both reef geometries are adequate for surfing, although the reef angle of 66° is more suitable for standard surfers, and the 45° angle is more adequate for advanced/professional surfers. A morphodynamic study should be carried out to analyze the efficiency of the artificial surf reef for coastal protection. DOI: 10.1061/ (ASCE)WW.1943-5460.0000128.

Using 3D Modelling Techniques for Surveys in Two Dimensional Scale Model Tests of Breakwaters

Abstract This paper focuses on a study of different methodologies for surveying two-dimensional scale models of rubble mound breakwaters. Tests were conducted in one of the LNEC’s irregular wave flumes and involved the use of four different methodologies using photogrammetric and 3D scanning techniques. This paper describes the materials and methods used during the experiments, as well as the results obtained. The data analysis contains the profiles and comparison of the meshes used in each of the techniques, in order to evaluate their application in scale model tests of rubble mound breakwaters. Also, the specific experimental conditions needed for using each of these techniques were investigated.

A Web Platform for the Systematic Monitoring of Coastal Structures.

Due to both its geographic location and maritime importance, Portugal is equipped with a large number of port infrastructures, the majority of which built for goals such as to guarantee the tranquility of the sheltered areas of the harbour basins, to help controlling sedimentation by guiding the currents, to protect water taken from thermoelectric plants, amongst others. In Portugal, the most common of these structures is the rubblemound breakwater. Due to its characteristics, maintenance or repair works are common throughout its lifetime. However, the need for these repair works should be evaluated in advance, in order to avoid significant costs associated to those works or, even worse, the collapse of the structure. It is therefore quite important to evaluate the Present Condition of the structure, as well its Evolution and Risk Conditions. The Present Condition is periodically checked on-site and all relevant data gathered is recorded, by filling in inspection forms, in order to perform further comparisons and analyses with previous inspections of the structure, as to eventually characterize Evolution and Risk conditions. To expedite all this process and prevent likely occurrence of errors in data collection, a monitoring tool, supported through a map-based online geographic information system (WebGIS) was developed, enabling the georeferencing of the structures concerned. This system adapts to the location of the user’s device and to the capacities of the device itself. Media data, such as photos and videos can be associated to the structural data collected. The resulting platform was successfully evaluated by the involved researchers from Portuguese National Laboratory for Civil Engineering (which are the end users of the system), and by non-expert users.

Application to the Port of Sines of a new tool for risk assessment in port navigation

This paper describes a first approach on the risk assessment in port navigation using GUIOMAR, an integrated system for port and coastal engineering modelling developed at the National Civil Engineering Laboratory (LNEC), Portugal, using a GIS software environment. A set of automatic procedures was designed to include a new methodology based on the amplitude of the wave-induced vertical movement of a ship along its trajectory. In this methodology, the risk in port navigation is assessed on the basis of a combination of the probability of exceedance of a pre-set threshold for the ship’s vertical movements and its consequences. To test the new procedures, a set of sea wave records obtained at the Sines wave-buoy from 1988 to 2002 was transferred into Sines Port using two numerical models of sea wave propagation and deformation (SWAN and DREAMS), included in the GUIOMAR system. The numerical model WAMIT was used for estimating the wave-induced ship’s vertical movements inside the port. By applying the new procedures, automatic generation of risk maps was carried out for navigation in the vicinity of the West breakwater of the Port of Sines. The recent developments contribute towards a more versatile and efficient GUIOMAR system, which results in a more adequate tool to support decision-making processes in port and coastal management.