Joaquim Pais-Barbosa

This study investigates the influence of wave-climate datasets derived from in situ measurements and reanalysis models on predictive modelling accuracy for coastline evolution, focusing on the IJmuiden coastal stretch in The Netherlands. By analyzing wave parameters, sediment dynamics, and nourishment interventions, the research evaluates the performance of a numerical model in simulating shoreline changes over a 40-year period. Using the LTC (Long-Term Configuration) model, scenarios incorporating artificial sand nourishment volumes of 200,000 m³/year and 250,000 m³/year were tested against conditions without nourishment. The results highlighted the critical role of significant wave height, direction, and dataset variability in sediment accretion and erosion patterns. Datasets from in situ measurements (Measured-YM6) and reanalysis sources (ERA5, AENWS-WPR, and AENWS-WPR North) demonstrate variable performance, with ERA5 proving to be the most reliable under both nourished and non-nourished scenarios. The findings emphasize the importance of integrating high-resolution wave datasets into numerical models to improve predictions, optimize nourishment strategies, and enhance coastal resilience against erosion. The study underscores the necessity of nourishment interventions to mitigate sediment loss, stabilize shorelines, and support sustainable coastal-management practices in the face of climate change.

Lopes, V., Pais-Barbosa, J., Taveira-Pinto, F. and Veloso-Gomes, F., 2011. Beach cusps: Using multivariate data analysis techniques for the identification of important variables and for predicting their spacing. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 1106 – 1110. Szczecin, Poland, ISSN 0749-0208 A beach cusp is defined as a cuspate feature which usually occurs in groups along the foreshore as a series of alternating horns (pointing seaward) and embayments. No formulation has yet been capable of providing accurate estimates of beach cusp spacing (distance between two consecutive horns) and no theory has been able to explain their formation. In this work, we try to identify important variables in the process of cusp formation and to develop a statistical tool capable of predicting beach cusp spacing. Three multivariate data analysis techniques, Multiple Linear Regression (MLR), Principal Component Analysis (PCA) and Principal Component Regression (PCR) were used to try to achieve this objective. Multiple linear regression attempts to model the relationship between two or more explanatory variables and a response variable by fitting a linear equation to observed data. Principal component analysis (PCA) involves a mathematical procedure that transforms a number of possibly correlated variables into a number of uncorrelated variables called principal components, related to the original variables by an orthogonal transformation. Principal component regression is a method that combines MLR with PCA. Two regression equations were derived. MLR equation explains almost 80% of the variance in cusp spacing, and there is no strong evidence that this model has multicollinearity problems. Standardized PCR equation explains 83,4% of the variance. Wave breaking height is, for the dataset used in this work, the most important variable. Variables other than those included in this work should also be important in determining beach cusp spacing.

This work aims to provide a more complete characterization of coastal erosion mitigation and climate change adaptation measures by presenting a participatory approach that integrates medium- to long-term perspectives, considering simultaneously social, environmental, economic and engineering dimensions to help decision makers implement sustainable climate change adaptation (CCA) strategies. The work lists, explains and characterizes existing climate change mitigation and adaptation measures as well as their costs and positive and negative social, environmental and economic impacts, in three distinct databases. These databases are discussed, complemented and validated in participatory moments with local stakeholders of the Ovar Municipality, Portugal, which represents the case study to support the proposed methodology. Although Ovar is a pilot case, the integrated framework for resilient CCA has a global application with respect to methodologies and concepts. The proposed approach is useful to help coastal management entities to engage in more efficient, effective and beneficial planned action to mitigate coastal erosion and adapt to future climate change effects. The open-source databases and the participatory approach facilitate decision makers and coastal communities to navigate the complexity of solutions and build consensus around collective actions for coastal areas.

Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 10⁶ m³ shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km² and 12 km², respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 10⁶ m³) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere.

This work aims to shed some light on longshore sediment transport (LST) in the highly energetic northwest coast of Portugal. Data achieved through a sand-tracer experiment are compared with data obtained from the original and the new re-evaluated longshore sediment transport formulas (USACE Waterways Experiment Station’s Coastal Engineering and Research Center, Kamphuis, and Bayram bulk formulas) to assess their performance. The field experiment with dyed sand was held at Ofir Beach during one tidal cycle under medium wave-energy conditions. Local hydrodynamic conditions and beach topography were recorded. The tracer was driven southward in response to the local swell and wind- and wave-induced currents (Hsb=0.75m, Tp=11.5s, θb=8−12°). The LST was estimated by using a linear sediment transport flux approach. The obtained value (2.3×10−3m3⋅s−1) approached the estimation provided by the original Bayram formula (2.5×10−3m3⋅s−1). The other formulas overestimated the transport, but the estimations res...

Silva, R., Veloso-Gomes, F. and Pais-Barbosa, J., 2013. Morphological Behaviour of Costa da Caparica Beaches Monitored during Nourishment Operations. Coastal erosion is a common problem along sandy shores in Europe, a result of its dynamic nature, anthropogenic influences and the effects of climate change. The coastal stretch Cova do Vapor-Costa da Caparica, located south from Tagus River, evidences chronic erosion problems since the 60's. It was necessary to construct a series of defence structures that more or less stabilized the beaches for nearly 30 years, although subjected to occasional overtopping and to increasing urban pressure and tourism. A worsening of the erosion situation from the winter of 2000/01 required a new intervention, which was envisaged in several phases, including the rehabilitation of the structures and the annual nourishment of the beaches. The nourishment operations were accompanied by a topo-hydrographic monitoring program, which complemented a database for the time p...

Lopes, V., Baptista, P., Pais-Barbosa, J., Taveira-Pinto, F., Veloso-Gomes, F., 2013. DGPS based methods to obtain beach cusp dimensions. Statistical correlations between wave parameters and cusp dimensions other than spacing may provide insight into which processes intervene in beach cusps formation and evolution. However, there is little information about cusp dimensions such as cusp depth, height or elevation. The aim of this work is to evaluate and compare different methods to determine beach cusp dimensions in order to assess which one produces more accurate, extensive and easy-to-achieve results. For this purpose some beach surveys were carried out at Ofir beach, located on the Portuguese west coast. Each one of the methods uses different sampling and processing strategies to obtain beach cusp dimensions. In method 0 cusp dimensions were determined using only two tape measures. The remaining 4 methods use Differential Global Positioning System (DGPS). Methods 3 and 4 provide values for cusp spacing, height, elevation and depth whilst methods 1 and 2 provide values for the first three parameters only. If one is only interested in measuring beach cusp spacing, height and elevation, then method 1 seems to be more adequate, due to its ease in sampling and in dealing with the data processing. Values of spacing, height and elevation obtained via Method 1 are the most accurate ones. On the other hand, if one wishes to perform a more detailed analysis, including parameters other than the above-mentioned and, for instance, to produce Digital Elevation Models (DEM), a combination of Method 1 and Method 3 or 4 is more appropriate.