IHCantabria research staff develop a methodology for a more accurate characterisation of the agitation climate in harbours

Research staff from the Hydrodynamics and Coastal Infrastructures group of the Institute of Environmental Hydraulics of the University of Cantabria (IHCantabria) have developed a numerical methodology for a more precise characterisation of the historical agitation climate inside harbours. This study, entitled “Wave downscaling strategies for practical wave agitation studies in harbours”, has recently been published in the international journal Coastal Engineering.

The climatic wave conditions condition the development of port operations in a harbour terminal at the quay. A proper characterisation of port agitation is essential for the assessment of port operability.

In common practice, agitation studies are based on numerical modelling of the port agitation response to the external wave climate. In other words, they are based on numerical simulations of wave climate propagation from outside to inside the port. Therefore, the quality of the results depends, on the one hand, on the numerical strategy adopted and, on the other hand, on the accuracy of the definition of the external wave climate.

The central aspect to be highlighted in this work is the increased accuracy in the estimation of the rough historical climate achieved, on the one hand, thanks to a high-precision characterisation of the extreme wave climate in front of the harbour using a more realistic representation of the wave energy distribution. And, on the other hand, through a dynamic propagation strategy where each sea state in a 40-year time series is propagated from deep water to the inner harbour, hour by hour, without using statistical reconstruction techniques.

The article also presents several alternatives for estimating port agitation, based on different approaches both for the propagation strategy and for the definition of the outer wave in the agitation modelling, evaluating the balance between the quality of the results and the computational cost required.

All of them are applied in a real scenario, in the dock of Africa (Port of Las Palmas), where the external wave climate has a highly multimodal character, i.e. the external wave energy comes from a significant variability of frequencies and directions. The analysis presented here is particularly relevant in areas such as this one, with a multimodal climate. An adequate characterisation of the maritime environment in front of the port is fundamental for any agitation study.

In a complete validation process, in each of the phases and for each of the proposed strategies, the level of accuracy achieved has been evaluated by comparing the numerical results with accurate instrumental data. In a comparative analysis, the advantages, limitations, accuracy and computational cost of each are presented, making it possible to identify the most appropriate strategy for each practical application, depending on the context and situation.

This comparative analysis has made it possible to quantify the improvements achieved in characterising the historical response of port agitation, achieving a reduction in the uncertainty of the results of around 50% of the agitation predictions obtained with the most accurate strategy compared to other commonly used approaches.

These improvements in the characterisation of the port’s agitation response to external wave climate can be fundamental in practical analyses of port operations where operational downtime is quantified based on operational thresholds associated with maximum allowable agitation values.

The proposed methodology can significantly reduce uncertainty in port design applications, acquiring particular importance in optimising solutions and designs focused on maximising the operability of any port. This analysis can also gain particular relevance in port areas with a maritime climate affected by the effects of climate change, where the agitation response can be affected due to alterations in the climatic conditions of the external waves.  IHCANTABRIA RESEARCH STAFF DEVELOP A METHODOLOGY FOR A MORE ACCURATE CHARACTERISATION OF THE AGITATION CLIMATE IN HARBOURS.

Research staff from the Hydrodynamics and Coastal Infrastructures group of the Institute of Environmental Hydraulics of the University of Cantabria (IHCantabria) have developed a numerical methodology for a more precise characterisation of the historical agitation climate inside harbours. This study, entitled “Wave downscaling strategies for practical wave agitation studies in harbours”, has recently been published in the international journal Coastal Engineering.

The climatic wave conditions condition the development of port operations in a harbour terminal at the quay. A proper characterisation of port agitation is essential for the assessment of port operability.

In common practice, agitation studies are based on numerical modelling of the port agitation response to the external wave climate. In other words, they are based on numerical simulations of wave climate propagation from outside to inside the port. Therefore, the quality of the results depends, on the one hand, on the numerical strategy adopted and, on the other hand, on the accuracy of the definition of the external wave climate.

The central aspect to be highlighted in this work is the increased accuracy in the estimation of the rough historical climate achieved, on the one hand, thanks to a high-precision characterisation of the extreme wave climate in front of the harbour using a more realistic representation of the wave energy distribution. And, on the other hand, through a dynamic propagation strategy where each sea state in a 40-year time series is propagated from deep water to the inner harbour, hour by hour, without using statistical reconstruction techniques.

The article also presents several alternatives for estimating port agitation, based on different approaches both for the propagation strategy and for the definition of the outer wave in the agitation modelling, evaluating the balance between the quality of the results and the computational cost required.

All of them are applied in a real scenario, in the dock of Africa (Port of Las Palmas), where the external wave climate has a highly multimodal character, i.e. the external wave energy comes from a significant variability of frequencies and directions. The analysis presented here is particularly relevant in areas such as this one, with a multimodal climate. An adequate characterisation of the maritime environment in front of the port is fundamental for any agitation study.

In a complete validation process, in each of the phases and for each of the proposed strategies, the level of accuracy achieved has been evaluated by comparing the numerical results with accurate instrumental data. In a comparative analysis, the advantages, limitations, accuracy and computational cost of each are presented, making it possible to identify the most appropriate strategy for each practical application, depending on the context and situation.

This comparative analysis has made it possible to quantify the improvements achieved in characterising the historical response of port agitation, achieving a reduction in the uncertainty of the results of around 50% of the agitation predictions obtained with the most accurate strategy compared to other commonly used approaches.

These improvements in the characterisation of the port’s agitation response to external wave climate can be fundamental in practical analyses of port operations where operational downtime is quantified based on operational thresholds associated with maximum allowable agitation values.

The proposed methodology can significantly reduce uncertainty in port design applications, acquiring particular importance in optimising solutions and designs focused on maximising the operability of any port. This analysis can also gain particular relevance in port areas with a maritime climate affected by the effects of climate change, where the agitation response can be affected due to alterations in the climatic conditions of the external waves. 

More information: https://doi.org/10.1016/j.coastaleng.2022.104140