Transport, Infrastructure and Building Spain
Vulnerabilities - Spain
Changes in coastal wave patterns due to the effect of climate change can affect harbour agitation (oscillations within the port due to wind waves). Variations in wave height would directly modify the amount of energy penetrating into harbours. Also, changes in wave period or direction would affect propagation processes such as shoaling, refraction and diffraction (1). Wave penetration into harbours would affect port operability. The activities in the harbour areas are strongly dependent on wave conditions, especially in relationship with the entrance and exit of the ships in safe conditions, but also for the regular harbour operations (2), including ship mooring and cargo loading/unloading.
The effect of climate change on wave-driven harbour agitation has been studied for 13 Spanish harbours located on the Catalan coast (NW Mediterranean). This was done for the periods 1971–2000 and 2071–2100. Wave projections were obtained with a wave model (SWAN) forced by winds generated with five combinations of global (GCMs) and regional circulation models (RCMs) considering the moderate A1B climate change scenario. In this study only variations in wave climate were taken into account; the effect of sea level change was not considered (1).
Results show a general slight decrease in the annual agitation in most of the ports. Compared to the results on an annual basis, a more clear decrease of agitation (12 out of 13 ports) was found in the winter. In contrast, in summer, an increase of agitation was found (9 of the 13 ports). Note that although in summer wave heights are relatively low, it is the period with greater activity in most of the studied ports (marinas). Although most of the model results indicate a reduction of agitation in ports, increasing their safety and operability, the possibility of an increase of wave heights within the port, reducing their safety and operability, is non-negligible (1).
One should be cautious when using these results, though. Uncertainty in these results is large, for a number of reasons, including inter-model variability and spatial variability (coastal orientation, port shelter and harbor design) (1).
One of the greatest impacts of sea level rise on seaports is related to wave overtopping (4). Sea level rise reduces the port breakwater’s freeboard, easing the passing of waves over such structures, increasing overtopping discharges and potentially endangering assets (boats, goods, warehouses...) located at the breakwater lee side. The future exposure of ports to sea level rise, therefore, emphasizes the need of considering climate change into long-term port management and planning (3).
The impact of sea level rise on wave overtopping of port breakwaters has been assessed for the ports along the Catalan (Spanish) coast (3). The 700 km long Catalan coast is located in the northwestern Mediterranean. Tidal range is about 20 cm. Along the Catalan Coast there are 47 seaports, 2 of which are large commercial harbours (Barcelona and Tarragona), 3 are small commercial (with facilities for leisure and fishing boats), 2 are industrial, 18 are mixed (fishing and leisure) and 22 are marinas.
The current base level and three scenarios of sea level rise were studied: 0.47 m (medium climate change), 0.88 m (high-end climate change) and 1.80 m (extreme high-end). In these scenarios land subsidence was included. For each scenario three storm conditions were considered: storms with return periods of 1, 5 and 50 years, respectively (3).
Currently, the number of vulnerable ports is low for frequent storms (with return periods of 1 and 5 years); this will not change much for sea level rise under both medium and high-end scenario of climate change. For the extreme high-end scenario of sea level rise, however, the number of vulnerable ports increases. During exceptional storms (50 years return period) one out of four Catalan ports experience risks due to overtopping under current climate conditions. This percentage may increase to about half of the ports in the extreme high-end scenario of sea level rise. The number of ports that may become very vulnerable increases with sea level rise, up to 30 % of the ports for the extreme high-end scenario of sea level rise (3).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Spain.
- Sierra et al. (2015)
- Rusu and Guedes Soares (2013)
- Sierra et al. (2016)
- Sierra and Casas-Prat (2014), in: Sierra et al. (2016)