Papers

In morphodynamic simulations of coastal lagoons should be included the several processes that contribute tosediment transport and consequently to bathymetric changes. The individual contribution of the tidal currents,waves, wind and rivers discharge should be considered to better characterize the study area evolution. In thework presented herein, an evaluation of single wave effects on the bathymetric changes of a coastal inlet ispresented, by neglecting the forcing of wind and rivers discharge in the numerical simulations and filtering thechanges produced by the tidal currents. The bathymetric changes, the residual sediment fluxes and thesedimentation rates induced by eight monochromatic waves at the inlet were analyzed. It was concluded that theinfluence of the simulated waves on the morphodynamics is restricted to the inlet and adjacent nearshore.Additionally, the changes in the bathymetry and residual sediment transport are strongly dependent on the waveheight forcing rather than on their frequency of occurrence. These conclusions emphasize the importance ofindependently analyze each wave, to better understand its impact in coastal systems dynamics.

Propagation of cracks was detected in an exhaust system that is manufactured with an austenitic stainless steel (AISI 316L). Usually cracks propagate from weld toes of butt and fillet weld joints located near the lower support ring of the structure. An in-service strain spectrum was collected with a high-temperature spot-welded strain gauge and temperature distribution was monitored with eight thermocouples spotwelded on the critical region of the exhaust system. A pressure spectrum was also acquired at its outlet section. A redesigned geometry of the structure was analysed by finite element method and its fatigue life assessed.

Lime-based mortars with admixtures of metakaolin (10,20 and 30 wt.%) and fine sepiolite (5 wt.%) were prepared with the aim of facilitating their use as repair mortars in low humidity conditions. The mechanical properties and the dynamic modulus of elasticity were studied after 28,90 and 180 days of curing. With increasing amount of metakaolin in lime mortars, improved mechanical strength was observed mainly after 90 days. Addition of fine sepiolite, due to its adsorption properties for storing water for later supply to the mortar system and its microfibrous morphology,led to an improvement of compressive and flexural strength of blended air lime/air lime-metakaolin mortars,especially at later ages of curing. Incorporation of fine sepiolite into air lime-metakaolin mortars resulted in comprehensive densification of the core of the mortars. Air lime mortar containing 5% of fine sepiolite and 20% of metakaolin appears to be an optimal admixture.

Em Portugal existe um grande número de pessoas a residir em vales a jusante de barragens. Assim, odesenvolvimento de metodologias para apoio à gestão integrada do risco nestes vales é de grande interesse práticopara a protecção da população. O presente artigo divide-se essencialmente em duas partes. A primeira parte édedicada à avaliação do risco que surge na sequência das cheias induzidas por acidentes nas barragens. A segundaparte versa sobre a mitigação do risco, através de um planeamento de emergência: interno, a nível da barragem, eexterno, a nível do vale a jusante.

Presently, conceptual and numerical sediment concentration modelling is largely based on the diffusionapproach. However, several works have shown that this approach is, frequently, unsuitable to model the profiledistribution of different grain size particles in the same flow. In order to understand the grain size effects onsuspended sediment concentration profiles under breaking wave conditions, a new data set was collected at threewest coast Portuguese beaches (Almagreira, Caparica and Comporta beaches). As expected, the relativeconcentration for the entire grain-size spectrum shows a systematic decrease with distance to the bed, thoughwith different profile shapes (exponential and power law). The analysis of the relative concentration profiles foreach sediment fraction show similar profile patterns; however, as expected, the decrease in the relativeconcentration with height strongly depends on particle size and assumes a different behaviour at each site. In thiscase, diffusion approach was unable to explain all the observed profile patterns, namely the overlapping ofcoarse sediment profiles and the different profile shapes in the same flow. These deficiencies were overcome bythe use of the convection-diffusion approach.

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This work investigates historical variation and trends in storm climate for the South Portugal region, using data from wave buoy measurements and from modelling, forthe period 1952 to 2009. Several storm parameters (annual number of storms; annual number of days with storms; annualmaximum and mean individual storm duration and annual 99.8th percentile of significant wave height) were used to analyse: (1) historical storminess trends; (2) storm parameter variability and relationships; and (3) historical storminess and its relationship to the North Atlantic Oscillation (NAO). No statistically significant linear increase or decreasewas found in any of the storm parameters over the period of interest. The main pattern of storm characteristics and extremewave heights is an oscillatory variability with intensity peaks every 7

The sustainable management of small, intermittent coastal systems is a challenging task due to the strongmorphological dynamics of their inlets, which causes hydrodynamics, morphodynamics and water renewal to behighly variable, at both seasonal and shorter time scales. This strong variability makes these coastal systems verysensitive to pollution events because the consequences of these events may differ significantly depending on thebathymetry at the time they occur. Here, a 3D modeling-based study of the water renewal variability of a smallcoastal system, the Aljezur stream, is presented, targeting 1) the impact of different measured bathymetricconditions, different seasonal forcings and processes included in its water renovation, and 2) the confirmation ofthe small role of light in the decay of fecal coliforms on the stream. The analysis is conducted for 4 distinctscenarios, including two real settings, using a 3D baroclinic model and an associated particle model. Resultsconfirm the major role of bathymetry on the residence times of the Aljezur stream, leading to 100% differences.Wind is shown to have a significant impact on the water renovation, as well as the instant of particle releasewithin the tidal cycle. A low permanence of particles in the upper layer of the water column, defined throughlaboratory experiments using the stream water, confirmed the small importance of light in promoting fecalbacteria decay in this stream.

Referem-se os principais aspetos do desempenho dos elementos e estruturas de madeira que são afetados pelas condições ambientais. Apresentam-se os estudos conduzidos para obter informação relevante sobre as condições de serviço e discutem-se algumas situações paradigmáticas em que o conhecimento dessas condições é determinante para garantir a resistência e a durabilidade das estruturas de madeira.