A study of air-sea interaction processes on water mass formation and upwelling in the Mediterranean sea

Air-sea interactions are a key process in the forcing of the ocean circulation and the climate. Water Mass Formation is a phenomenon related to extreme air-sea exchanges and heavy heat losses by the water column, being capable to transfer water properties from the surface to great depth and constituting a fundamental component of the thermohaline circulation of the ocean. Wind-driven Coastal Upwelling, on the other hand, is capable to induce intense heat gain in the water column, making this phenomenon important for climate change; further, it can have a noticeable influence on many biological pelagic ecosystems mechanisms. To study some of the fundamental characteristics of Water Mass Formation and Coastal Upwelling phenomena in the Mediterranean Sea, physical reanalysis obtained from the Mediterranean Forecating System model have been used for the period ranging from 1987 to 2012. The first chapter of this dissertation gives the basic description of the Mediterranean Sea circulation, the MFS model implementation, and the air-sea interaction physics. In the second chapter, the problem of Water Mass Formation in the Mediterranean Sea is approached, also performing ad-hoc numerical simulations to study heat balance components. The third chapter considers the study of Mediterranean Coastal Upwelling in some particular areas (Sicily, Gulf of Lion, Aegean Sea) of the Mediterranean Basin, together with the introduction of a new Upwelling Index to characterize and predict upwelling features using only surface estimates of air-sea fluxes. Our conclusions are that latent heat flux is the driving air-sea heat balance component in the Water Mass Formation phenomenon, while sensible heat exchanges are fundamental in Coastal Upwelling process. It is shown that our upwelling index is capable to reproduce the vertical velocity patterns in Coastal Upwelling areas. Nondimensional Marshall numbers evaluations for the open-ocean convection process in the Gulf of Lion show that it is a fully turbulent, three-dimensional phenomenon.

Touristic water demand: analysis and validation of drinking water consumption data and hotel characterization in Benidorm (Spain)

The work analyses the tourist water demand in Benidorm, a sun-and-sand destination ranked fourth in Spain by number of visitors, where tourism competes with local residents, nature, agriculture and industrial sectors for scarce water resources. In particular, we have studied the correlation between the water consumption of 83 hotels in Benidorm and their characteristics and services which can impact water use. For this purpose, we have examined the water consumption billed, by the water utility company HIDRAQUA in the period January 2010 - October 2022, to the tourist structures in the municipality of Benidorm, and we have explored the hotels’ features, thanks to the collaboration of the tourism and hotels association HOSBEC. To give a better understanding and contextualization of our analysis we first described explained the of the complex water supply system and the efforts that have been made to reduce the threat posed by the peculiar climate conditions of the region. We saw that the water consumption per guest has slightly decreased in the recent years and that the tourist flux has increased: the global pandemic posed a stop to travels for more than one year, but now both the tourist flux and the tourist water consumption are reaching pre-pandemic level. We found that larger hotels, and in particular the ones opened all the year, that probably tend to offer more water-demanding service with respect to the seasonal ones, have higher water consumption per bed. From the analysis of the role of the different hotel characteristics over the water demand patterns, we found that water use increases with the increase in the hotel category and in the ratio between the surface area of the swimming pool and hotel size (number of beds). Other factors impacting the consumption are the presence of an on-site laundry for washing the hotel linen, the garden, and the implementation of environmental policies for water-saving.