Search

The final publication is available at Springer via http://dx.doi.org/ 10.1007/s10113-015-0923-x In the context of climate change, this study evaluates the impact on the long-shore and cross-shore sediment transport (LST and CST) along the Catalan coast (NW Mediterranean Sea) derived from climate projections obtained from five combinations of regional and global circulation models (RCMs and GCMs). Special emphasis is given to how inter-model variability translates from wave projections to wave-driven coastal impacts, which is still poorly known. Results show that the uncertainty is in general larger, especially for LST, for which the discrepancies among regional models are more relevant than those associated with the forcing wave parameters. Such increase in the uncertainty can be explained by the nonlinear processes involved, and the role of the forcing wave parameters having sometimes competing effects (e.g. wave height vs. wave direction). This illustrates that the performance of each RCM–GCM can vary from forcing to impact parameters; hence, the suitability of a particular RCM–GCM to evaluate a certain impact should be assessed based on its ability to properly simulate such impact. In this regard, LST and CST rates computed using empirical formulae that integrate several wave climate parameters, as in this study, can be used as a non-computationally expensive tool to assess the suitability of a given RCM–GCM to project changes in coastal dynamics.

Menorca (Balearic Islands) only covers 2% of its electricity needs with renewable energy sources, which is far below the European Union's objective of obtaining 20% of its energy from these sources. This study analyses the island's wave energy resources using a 17-year series of data obtained from numerical modeling (forecast). The spatial distribution of wave power is analyzed using data from 12 points around the island. The obtained resources (average wave power, around 8.9 kW/m; average annual wave energy, about 78 MW h/m) are relatively modest but among the largest found in the Mediterranean Sea. The northeast and east of the island are the most productive areas. Considerable seasonal variability is found, with winters being rather energetic and summers quite mild. The power matrices of three wave energy converters (WECs) are considered to assess the average power output at all of the points. Four places are identified as the best candidates for WEC deployment, with non-negligible productivity that can be exploited to supply energy to small villages.

The final publication is available at Springer via http://dx.doi.org/10.1007/s10113-016-0972-9 The potential impact of climate change on port operations and infrastructures has received much less attention than the corresponding impact for beach systems. However, ports have always been vulnerable to weather extremes and climate change could enhance such occurrences at timescales comparable to the design lifetime of harbour engineering structures. The analysis in this paper starts with the main climatic variables affecting harbour engineering and exploitation. It continues with a review of the available projections for such variables first at global scale and then at a regional scale (Catalan coast in the western Mediterranean) as a study case for similar environments in the planet. The detailed assessment of impacts starts from downscaled projections for mean sea level and wave storms (wind not considered in the paper). This is followed by an analysis of the port operations and infrastructure performance that are relevant from a climate perspective. The key climatic factors here considered are relative sea level, wave storm features (height, period, direction and duration) and their combined effect, which is expected to produce the highest impacts. The paper ends with a discussion and some examples of analyses aiming at port adaptation to future climate change.

[1] Projected future regional wave climate scenarios at a high temporal-spatial scale were obtained for the NW Mediterranean Sea, using five combinations of regional-global circulation models. Changes in wave variables were analyzed and related to the variations of the forcing wind projections, while also evaluating the evolution of the presence of the different types of sea states. To assess the significance of the changes produced, a bootstrap-based method was proposed, which accounts for the autocorrelation of data and correctly reproduces the extremes. For the mean climate, relative changes of Hs up to ±10% were obtained, whereas they were around ±20% for the extreme climate. In mean terms, variations of Hs are similar to those associated with wind speed but are enhanced/attenuated, respectively, when fetch conditions are favorable/unfavorable. In general, most notable alterations are not in the Hs magnitude but rather in its direction. In this regard, during the winter season, it is interesting to note that the significant deviations between the results derived from the two global circulation models are larger than those between regional models. ECHAM5 simulated an enhanced west wind flow that is translated into more frequent W-NW waves, whereas the HadCM3Q3 global model gives rise to the east component, which contributes to a higher intensity and number of storms coming from such a direction and directly affects the wind-sea/swell distribution of coastal stretches that face east, like the Catalan coast. Different patterns of change were obtained during the summer when a common rise of NE-E waves was found.

Lanzarote (Canary Islands, Spain) is a UNESCO Biosphere Reserve (since 1993) located in the Atlantic Ocean. The island is aiming to change its energy production model in order to reduce its dependence on external, fossil-fuel-based energy sources. The local authorities hope to develop an energy production model based on clean, renewable sources, such as wave energy converters (WECs). This study analyses the island's wave energy resources using a 51-year series of data obtained from numerical modelling (hindcast and forecast). The spatial distribution of wave power is analysed using data from nine points around the island. Significant resources (average wave power exceeding 30 kW/m and average annual wave energy of more than 270 MW h/m) are found to the north of the island, as well as to the west and the east (average wave power 25–30 kW/m). Considerable seasonal variability is found, with winters being rather high-energetic and summers quite mild. Variability coefficients are computed in order to select the best locations for WECs; the composition of the resource at each location is examined in terms of sea states in order to evaluate the suitability of WEC installation. Finally, three sites with similar conditions, all located on the north side of the island, are selected as the best candidates for WEC deployment.

Sanchez-Arcilla, A., Gonzalez-Marco, D., Sospedra, J., Palomares, A., Sierra, J.P., Schuon, F., Espino. M., Grifoll, M., Pallares, E., Jimenez, P.A. and Navarro, J. 2013. Meteo-oceanographic simulations and observations to assess the potential of offshore wind farm in a NW Mediterranean shelf. Renewable marine energy is important in squeezed Mediterranean coastal zones. Wind turbines deployed over the narrow Catalan continental shelf require accurate wind/wave/current fields for a reliable design, operation and maintenance. This paper presents the large (comparative to other open sea areas) errors in meteo-oceanographic predictions for semi enclosed domains such as the coastal sea off the Ebro Delta coast. The emphasis is on the sequence of high resolution coupled and nested models and the role of in situ collocated measurements for calibration and validation.

In the context of wave climate variability, long-term alterations in the wave storminess pattern of the Catalan coast (northwestern Mediterranean Sea) are analysed in terms of wave energy content and wave direction, on the basis of wave hindcast data (from 44-year time series). In general, no significant temporal trends are found for annual mean and maximum energy. However, the same analysis carried out separately for different wave directions reveals a remarkable increase in the storm energy of events from the south, which is partly due to a rise in the annual percentage of such storms. A case study of Tarragona Port (on the southern Catalan coast) highlights the importance of including changes in wave direction in the study of potential impacts of climate change. In particular, an increase in the frequency of storms from the south leads to greater agitation inside the Port.

The objective of the present work is to analyse how changes in wave patterns due to the effect of climate change can affect harbour agitation (oscillations within the port due to wind waves). The study focuses on 13 harbours located on the Catalan coast (NW Mediterranean) using a methodology with general applicability. To obtain the patterns of agitation, a Boussinesq-type model is used, which is forced at the boundaries by present/future offshore wave conditions extracted from recently developed high-resolution wave projections in the NW Mediterranean. These wave projections were obtained with the SWAN model forced by present/future surface wind fields projected, respectively, by 5 different combinations of global and regional circulation models (GCMs and RCMs) for the A1B scenario. The results show a general slight reduction in the annual average agitation for most of the ports, except for the northernmost and southernmost areas of the region, where a slight increase is obtained. A seasonal analysis reveals that the tendency to decrease is accentuated in winter. However, the inter-model variability is large for both the winter and the annual analysis and many ports present at least one model configuration showing a rise in the agitation. Conversely, a general increase is found during summer, which is the period with greater activity in most of the studied ports (marinas). The latter result is more consistent among models, which illustrates the lower inter-model variability in summer.

A descriptive investigation on the wind wave climate off the Ebro delta has been conducted on the basis of time series of data collected after 1978. Sea states have been classified into phenomenological cathegories according to available directional data. For selected records, illustrating the different wave conditions, statistical and spectral analyses have been performed so as to assess the short-term characteristics of the wave climate. Regarding the longer-term evolution, correlations among the main wave parameters have been established. Theoretical probability distributions have been fitted to the observed frequency histograms in order to complete the description of the average wave climate. Furthermore, some statistics of extreme wave heights have also been considered.

The effects of climate change are currently a red-hot issue in the scientific community. However, little attention has been paid to the effects of climate change on the wave climate and, in particular, on wave directionality. In this study, we developed a methodology of trend analysis and extrapolation of mean wave climate. We used the parameters of a typical wave rose: frequencies of wave height intervals and directional sectors. The trend over time was estimated by means of linear regression analysis after applying a transformation according to the nature of the (compositional) data. Then, the wave climate was extrapolated up to 2050 assuming the same previously estimated trend and part of the uncertainty was assessed with the bootstrapping technique. Additionally, to get an idea of the magnitude of the consequences of the identified trends, we carried out an impact assessment, in terms of coastal morphodynamics and harbour operability, comparing the present situation with the extrapolation. To assess the impact on coastal morphodynamics, we compared the gradients of long-shore sediment transport to evaluate possible changes in beach retreat/accretion tendency, and to assess harbour operability, we studied the possible impact on harbour agitation in three port case studies. This study was carried out on the Catalan coast (NW Mediterranean Sea) and was based on 40 nodes of 44 years of wave hindcast data. The main impacts on the wave climate were found to be a reduction in the waves coming from the north and northeast and an increase in events coming from the south. This apparently significant change in directionality could result in changes in the prevailing dynamic pattern along more than 70 % of the Catalan coast (e.g. some apparently stable beaches could become erosive) although these results have associated a large uncertainty and are not statistically significant. On the other hand, harbour agitation is expected to increase with statistical significance (by up to 18 % on average) because the studied ports, like most of Catalonia’s ports, are oriented towards the south-southwest.

Harbours are essential infrastructures for economic activity that are susceptible to impacts from climate change driven processes, like sea level rise (SLR), or alterations in wave patterns. In this paper, the impact of climate change on wave agitation in ports (oscillations due to wind waves) and, therefore, on port operability is analyzed. This is carried out through a numerical model suite, considering the RCP8.5 scenario to project changes in wave fields, and three values of SLR. The study is particularized for the port of Barcelona (NW Mediterranean), but the used methodology can be applied to other harbours. Results suggest that changes due only to waves will be minimal and with a general trend to slightly decrease wave agitation. On the contrary, the effect of SLR and the associated increase of water depth will favor the penetration of waves within the harbour, leading to a certain reduction of port operability, the magnitude of which will depend on the SLR value. However, the complexity of wave patterns within the harbours, due to multiple reflections of waves on port structures, implies that the reduction of operability strongly varies according to the position and orientation of the berthing zones inside the harbour.

In this paper, the impact of sea level rise (SLR) throughout the 21st century in the overtopping of port breakwaters is analyzed at a regional scale, focusing on the Catalan coast (NW Mediterranean). The study is made considering three scenarios of SLR and two levels of storminess, computing the overtopping discharges in 47 ports to assess those exceeding a tolerable threshold and to roughly estimate the monetary value of the consequences of such discharges. Possible adaptation measures are examined, selecting the most cost-effective and assessing the cost of its implementation for the different scenarios and two damage levels. Results show that, as it could be expected, the number of ports affected by overtopping will increase with SLR, as well as the economic impact. Another remarkable finding of this paper is the significant savings in adaptation measures achieved allowing a minimum level of damage in contrast to the zero-damage option.

This study proposes a computationally inexpensive statistical method for modeling ocean wave heights, focusing particularly on modeling wave heights in near-shore areas. A multiple linear regression is used to predict significant wave heights (Hs) using predictors derived from the sea level pressure (SLP) field, including the use of squared SLP gradients to represent geostrophic winds. One time step lagged Hs is also included as a predictor, which could be interpreted as the first order derivative in the spectral energy balance governing equation. Further, based on the frequency/directional dispersion theory of waves, the swell component is accounted for by using a set of selected principal components derived from the squared SLP gradient vectors (including magnitudes and directions). The effect of non-Gaussian (non-negative) variables is also assessed by applying two types of transformation to the data.The proposed method is evaluated and shown to have good skills for the study area (Catalan coast). This method can be used to project possible future wave climate change for use in coastal impact assessment studies. It is used in this study to project the wave climate for the study area that corresponds to 5 sets of regional climate model (RCM) atmospheric projections, which were made by different RCMs forced by the same global circulation model (GCM), or by the same RCM forced by two GCMs. For the season analyzed (winter), the results show that the uncertainty due to using different GCMs to drive the same RCM is greater than that due to using different RCMs driven by the same GCM.

The aim of this paper was to analyse how changes in wave patterns, due to the effect of climate change, can affect wave energy power and yield around Menorca (NW Mediterranean Sea). The present and future wave energy conditions were derived from recently developed high-resolution wave projections in the NW Mediterranean. These wave projections were forced by surface wind fields obtained, respectively, by 5 different combinations of global and regional circulation models (GCMs and RCMs) for the A1B scenario. The results showed that the projected future spatial and directional distributions of wave energy are very similar to those of the present conditions. The multi-model ensemble average illustrated a slight general decrease in the annual and seasonal wave power (except for summer). However, the inter-model variability is large since two models showed opposite trends to the other 3 in most cases. Such inter-model variability is lower(higher) for winter(autumn). Another result is the reduction of the temporal variability in the future, considering both the multi-model mean and each single model projection. Such a decrease is consistent with the future seasonal redistribution of energy throughout the year. This would entail an increase in the efficiency of wave energy converters deployed in this area due to the more regular temporal distribution of the energy.

In this paper, the wave energy potential in the western coast of France is assessed, analyzing 58 years of data from numerical models at 10 points located between latitudes 43º30'N and 47ºN. The study focuses on the temporal variability at different scales (monthly, seasonal and inter-annual). The northern part of this stretch is the most energetic (wave powers greater than 22 kW/m), with a decrease of the wave power southwards. The results show that both the wave power resource and the energy output of two wave energy converters (WECs) at the Atlantic coast of France have strong intra-annual and inter-annual variability. From one year to another the wave power may present variations of up to 200%, and the WEC energy output may almost double. These results illustrate that the average mean power alone is not sufficient for adequate wave resource quantification, and it is necessary to consider the intra-annual and inter-annual variability of the wave power and the WEC output when analyzing the potential installation of a wave energy farm in a certain area.

In this paper changes in the wave pattern of the Catalan coast are analyzed in terms of wave storminess and wave direction based on series of 44 years of hindcast wave data. The analysis is performed employing two different techniques: one resulting from the combination of regression and bootstrapping and the other applying a Bayesian method. Although the trends are, in general, null, in some locations there are clear changes in the wave directional frequencies. These changes can significatively affect coastal hydrodynamics and morphodynamics.

This study analyses the wave energy resource along the Atlantic coast of Morocco using a 44-year series of data obtained from numerical modeling (hindcasting). The spatial distribution of wave power is analyzed using data from 23 points along that coast. The estimated resources (average wave power up to 30 kW/m and average annual wave energy up to 262 MW h/m) are considerable and slightly lower than at the neighboring Canary Islands. The central part of this area (between latitudes 29°30'N and 34°N) is the most productive, while in the northern and southern parts the resource is significantly lower due to the shadow effect of the Iberian Peninsula and the Canary Islands, respectively. The study of the temporal variability indicates a considerable seasonal trend, being the wave energy resource over four times greater in winter than in summer. Moreover, the power matrices of two wave energy converters (WECs) are considered to estimate the average power output at all the studied points. Finally, a multi-criteria analysis is carried out considering five different factors in order to select the best places for WEC deployment.

The final publication is available at Springer via http://dx.doi.org/10.1007/s10113-015-0879-x The overtopping of port breakwaters may affect the assets located at the breakwater lee side. If adaptation measures are not taken, the sea level rise will increase the overtopping discharges putting those assets at significant risk. This study compares, at a regional scale, overtopping discharges over port breakwaters for three storm conditions (return periods of 1, 5 and 50 years) under present climate as well as for three scenarios of sea level rise based on recent projections. The results indicate that, for the worst storm and sea level rise conditions, the overtopping discharge would not be negligible (larger than 1 l/s/m) in 35 ports (84 %), in contrast to only 18 ports (42 %) being affected under present conditions. In addition, in 28 ports (65 %) the overtopping would be at least one order of magnitude larger than for present conditions. In the case of large storms, in 2 ports the overtopping discharge exceeds 200 l/s/m (the discharge that can initiate breakwater damage) under present conditions, while in the worst scenario of sea level rise the number of ports exceeding this value would be 7. On the other hand, the vulnerability of each port for which overtopping flow is greater than an acceptable discharge flux is assessed, and regional maps of vulnerability are plotted. For the worst storm conditions, 23 % of the Catalan ports have risks associated with overtopping under present climate conditions. This percentage would increase to 47 % in the worst sea level rise scenario.