Economic impact of overtopping and adaptation measures in Catalan ports due to sea level rise

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.Peer ReviewedPostprint (published version

Impact of climate change on wave energy resource: the case of Menorca (Spain)

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.Peer ReviewedPostprint (author's final draft

Analysis of the optimal deployment location for tidal energy converters in the mesotidal Ria de Vigo (NW Spain)

The potential power output expected from the installation of a tidal farm near the mesotidal Ria de Vigo (NW Spain) is assessed using two different tidal stream energy converters (TEC). For this, the results of a previous resource assessment based on a 28-day long hydrodynamic simulation are used. From this data we identify the areas susceptible of hosting the farms, select the optimal location for them, and assess the total available and extractable energy for each turbine type. Finally, using a simple farm design based on standard inter-turbine separation, we estimate the expected power supplied by the farm. Irrespective of the site, the total available tidal power in the areas susceptible of hosting the farms is around 150 MW; at the optimal location, the hourly extractable power is about 22.5 MW, of which only between 10% and 15% can be harnessed by the designed farms, powering between 4411 and 6638 homes. A local analysis of the most energetic subregions within these sites increases this ratio up to 30%. Nevertheless, the power output is sufficient to fulfil the needs of between 1660 and 2213 households, depending on the chosen site and the selected TEC.Peer ReviewedPostprint (author's final draft

Wave energy potential along the Atlantic coast of Morocco

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.Peer ReviewedPostprint (author's final draft

Vulnerability of Catalan (NW Mediterranean) ports to wave overtopping due to different scenarios of sea level rise

The final publication is available at Springer via http://dx.doi.org/10.1007/s10113-015-0879-xThe 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.Peer ReviewedPostprint (author's final draft

Quantification of the tidal stream exergy in the ría de Vigo (NW Spain)

The exergy of the tidal currents in the ría de Vigo area (NW Spain) is quantified using the results of a 28-day long simulation of the tidal flows. The results show that the northernmost strait connecting the ría with the Atlantic Ocean is a promising site for tidal energy tapping, in contrast with the energetically weaker estuary. On the basis of the average power density (APD), a 7.5 km2 region is identified in this strait as the most advantageous area to install tidal energy converters (TECs), with a total annual exergy of around 3865 MWh/m2. Similar analyses using only 14-day simulations change this value in ±16%, depending on whether the tidal cycle considered is apogean or perigean. The study contributes to enlarge the inventory of sites along the NW Spanish coast at which tidal stream energy can be potentially extracted.Peer ReviewedPostprint (author's final draft

Modelling assessment of the tidal stream resource in the Ria of Ferrol (NW Spain) using a year-long simulation

The availability of tidal stream energy in the Ría of Ferrol (NW Spain) has been assessed using a long term hydrodynamic simulation (351 days). A priori, a strait in the central part of the estuary seems a promising site for tidal energy tapping, but the results show that barotropic currents rarely exceed 0.9 m/s during spring tides, with a maximum peak power density of 0.45 kW/m2 estimated at a spring tide mid-ebb. The maximum annual energy density is estimated at 415 kWh/m2, significantly lower than at other nearby estuaries. A comparison of the annual resource estimates shows that differences of up to 35% can be introduced depending on whether a simulation of one tidal cycle, one lunar month, or a full year is used for the calculations. This proves that usual tidal resource estimations, based on a single tidal cycle, can significantly misestimate the tidal energy potential of a site.Peer ReviewedPostprint (author's final draft

Green measures for Mediterranean harbours under a changing climate

Harbour operability may be hampered by climate change. Green solutions can be used to provide extra flexibility with respect to present grey infrastructure to adapt to, and mitigate, such functional disruptions with affordable costs. This paper assesses the performance of a green solution (a seagrass meadow) by assessing its effectiveness through numerical modelling. The analysis is carried out at two harbours that, under the present climate, are prone to wave agitation and overtopping problems. The efficiencies of different seagrass layouts are tested at both sites, by comparing the relevant hydrodynamic parameters. It is concluded that, for moderate sea level rise (SLR) rates, illustrated by the central trend of a medium scenario from the Intergovernmental Panel on Climate Change, the use of seagrass meadows would be effective enough to attenuate the impact of SLR on breakwater overtopping. In addition, the use of such measures could attenuate the increases in port agitation due to changes in wave direction caused by climate change. Nevertheless, the complexity of the interactions between hydrodynamics and seagrass would require periodic monitoring and re-evaluation to maintain acceptable risk levels, especially in case of extreme scenarios.Peer ReviewedPostprint (author's final draft

Coastal flooding and erosion under a changing climate: implications at a low-lying coast (Ebro delta)

Episodic coastal hazards associated to sea storms are responsible for sudden and intense changes in coastal morphology. Climate change and local anthropogenic activities such as river regulation and urban growth are raising risk levels in coastal hotspots, like low-lying areas of river deltas. This urges to revise present management strategies to guarantee their future sustainability, demanding a detailed diagnostic of the hazard evolution. In this paper, flooding and erosion under current and future conditions have been assessed at local scale at the urban area of Riumar, a touristic enclave placed at the Ebro Delta (Spain). Process-based models have been used to address the interaction between beach morphology and storm waves, as well as the influence of coastal environment complexity. Storm waves have been propagated with SWAN wave model and have provided the forcings for XBeach, a 2DH hydro-morphodynamic model. Results show that future trends in sea level rise and wave forcing produce non-linear variations of the flooded area and the volume of mobilized sediment resulting from marine storms. In particular, the balance between flooding and sediment transport will shift depending on the relative sea level. Wave induced flooding and long-shore sand transport seem to be diminished in the future, whereas static sea level flooding and cross-shore sediment transport are exacerbated. Therefore, the characterization of tipping points in the coastal response can help to develop robust and adaptive plans to manage climate change impact in sandy wave dominated coasts with a low-lying hinterland and a complex shoreline morphology.Peer ReviewedPostprint (published version

A review of potential physical impacts on harbours in the Mediterranean Sea under climate change

The final publication is available at Springer via http://dx.doi.org/10.1007/s10113-016-0972-9The 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.Peer ReviewedPostprint (author's final draft