The Evolution of the Water Quality Dynamics in Europe through Socio-Hydrological Modelling: Model Development

Nowadays, the water quality management has become a crucial concern all around the world and particularly in Europe. It is negligible remarking the importance of water in natural and human environment, but its quality and so its evolution through time could be fundamental aspects to understand its dynamics. The evolution of water quality in Europe from 1900 to today has been characterized by significant changes influenced by various factors such as industrialization, urbanization, agricultural practices, technological advancements, and environmental regulations. Tracking water quality dynamics in Europe from 1900 to the present involves understanding various historical, environmental, and socio-economic factors that have influenced water quality over time as internal and external forcings. For this reason, the aim of this thesis is that one to develop a qualitative socio-hydrological model able to reproduce the water quality evolution in Europe over the 20th and the 21st centuries and, moreover, to foresee its changes over the imminent future. It is important to highlight the background of this analysis: we look at a socio-hydrological model, an unconventional hydrological study that accounts for the water-human interactions and relationships. Consequently, in the following chapters, the socio-hydrological model is worked out following a step-by-step procedure: 1) The main variable, the water quality, is analysed considering its evolution over the past years in Europe. A general statement of the phenomenon is given, the interactions between internal and external variables, the domain and the scale of the phenomenon are defined; 2) The perceptual model is built up by developing the causal loop diagram which defines the feedbacks between each variables: water quality, environmental awareness, industrial polluting, economic health, demographic change and climate change; 3) The internal state variables are chosen and studied deeply; 4) Causal factors must be assessed and the basic relationships between each variable are work out; 5) The functional relationships are built using intuition, data analysis, related studies and consensus principles. In conclusion, the main goal of this thesis is to model the water quality evolution over time and so, be able to understand the strongest and weakest interactions between each variable in order to predict the possible future challenges for its management and also for the human health. Moreover, the model reveals that the most effective strategy to improve the water quality is not merely enacting green laws, setting limits, or investing in sustainable policies, as these actions primarily impact the economy rather than reducing pollution. If the State aims to swiftly address emerging environmental issues, it must focus on enhancing eco-friendliness by prioritizing green and sustainable technologies and production methods. Moreover, the socio-hydrological model describes the impact of demographic and climate change. In the future, demographic change may either delay or accelerate already known outcomes and has a more pronounced effect on industrial pollution production than on water quality. On the other hand, climate change is a forward-looking variable; its impacts are not apparent in the past or present. Therefore, this qualitative model underscores the importance of studying climate change and implementing mitigation and adaptation measures. Although its impacts may not seem alarming now, the potential future consequences could be much more severe.