Physical and economic impacts due to sea level changes and wind-waves around the Balearic Islands

Abstract

This thesis investigates and quantifies the impacts caused by climate change in the coasts of Balearic Islands (western Mediterranean Sea) from both a physical and an economic perspective. Two physical mechanisms that generate coastal hazards are considered in this work: mean sea-level rise and wind-waves. Their impacts are assessed, separately and jointly, in three case studies that have been selected due to the amount of available observations of nearshore waves, shoreline position and topo-bathymetries; these are two urban beaches (located in Mallorca island) and one natural beach (in Menorca island). The relevance of sandy coasts in the Balearic Islands, and in general in the Mediterranean coastal communities, is evident in terms of coastal protection but also from an economic point of view since sun-and-beach tourism is the main economic activity of the region. The physical impacts on the beaches are investigated using numerical modelling to simulate the shoreline retreat, the beach erosion and the beach vulnerability resulting from projected mean sea-level rise and wind-wave changes up to 2100. The methodology and the assumptions vary depending on the hydro- and morphodynamical processes required to study the coastal impacts in each case. In addition, numerical simulations are validated against observations whenever possible, prior to the application of the modelling setup under projected future conditions. Our results for urban beaches, highly anthropised and backed by infrastructures such as promenades and buildings, indicate a permanent loss of approximately half of the present-day beach area; in addition, the beach is expected to be almost completed flooded under storm conditions. In other words, urban beaches are unable to respond to long-term changes in the oceanic forces. In the case of the natural beach, our results anticipate that the beach will retreat at the expense of the dune area located behind it. A noteworthy finding is the importance of simulating the beach morphological features when assissing beach impacts, which play a key role in the beach erosion rates. The economic impact on sun-and-beach tourism is measured by means of a choice experiment application. More precisely, the shoreline retreat projections obtained for the urban beach cases studies are used to estimate the welfare loss that tourists would experiment in a future scenario characterized by a reduction of the beach size, in addition to two other climate-induced environmental changes. Data on the socioeconomic and the travel profile of tourists as well as their preferences for different policies aimed at reducing climate-induced environmental changes, was collected through a survey conducted in the high season of 2016 at the airport of Palma (Mallorca). Overall, results show that sun-and-beach tourists have a positive willingness-to-pay to reduce climate change impacts. At the same time, the mixed logit specification accounting for preference heterogeneity allows to find that the welfare loss varies across tourists depending on their socioeconomic and travel characteristics.