86. Water Management: The Central Italy Model and Its Dissemination

Water management in central Italy is characterized by a development model focused on producing energy from water, rather than on drainage and irrigation. Its history begins in the Middle Ages with the creation of the communal territories, and continues until the rise of the hydroelectric industry. As Italian towns developed, they did not simply restore Roman aqueducts, built mostly for celebrating the role of the Empire, but they adapted these structures to fulfil the needs of a growing urban population. Apart from the literature celebrating the relevance of restoration politics and the role of the River Tiber, this model is the same in the small towns and in the capital of the Papal State, Rome. The damage caused by flooding mostly affected urban buildings, but not agriculture, which was kept away from the danger areas surrounding rivers. To face the hazard of floods in towns, the simple techniques of hydraulic engineering known at the time were employed to channel and divert the water away. Of course, the early natural philosophers considered floods as a moment in the circulation of the water within the internal body of the Earth. In reality, the catastrophic floods of the 16th and 17th centuries seemed to be the product of both human action and climatic change. While the importance of hydraulic energy in the ancient world has still to be demonstrated, it has been well established for the Middle Ages and for the Modern Era. The four basic elements for supplying water and energy for the growing urban systems were: a canal and reservoir for maintaining a regular flow of water, the building of walls for the city and its mills, a masonry-lined canal for moving water under pressure to a horizontal water wheel powering a grain mill, and a means of conveying the water used by the mill to another reservoir. In spite of the long accepted tradition in the history of hydraulic technology, these mills seem to have been the most effective and labour-saving machines within the confines of central Italy. These systems often included vertical wheels which were used for different purposes such as fuelling mills, paper making and metal working. Irrigation is mainly a variant of the model: water from the mills was employed for specialized cultivation around and inside the city walls, when not employed for powering water wheels. The role of the rivers – the River Tiber was the only important one of the region – is quite different. They were used for transport and they were harnessed for power, as well as providing a receptacle for wastewater. Many questions have still to be defined by historical research. Among them, in the long-term, is the centre of urban water supply to be placed on rivers or on artificial aqueducts? And is the development of water technology generated by the planning of a central authority, or by the competition between the different entities? There is a real exchange of scientific and technological knowledge in the history of development, which allows us to consider “water science” as one of the “bases of civilization”.