Constructive Challenges in the Water Supply to Cities, from Roman Times to Modern Times. Some Reflections Based on the Portuguese Reality

Water, as an essential element for life, has always been present in the daily lives of societies. In the case of urban agglomerations, the quantities of water needed to supply them have in some cases been extremely challenging for human abilities, not only in terms of collecting it, but also in terms of transporting it and distributing it for final consumption by the population. Today, the lack of water continues to be a concern, taking centre stage in the global political agenda and in the UN's 2030 Sustainable Development Goals. Convinced that the lessons of history can help minimise the harmful effects of climate change, the aim of this work is to analyse some of the constructive and architectural solutions found by past societies to obtain water, from which we can learn to preserve and value this important resource. Our approach will focus on analysing cases that refer mainly to the urban landscapes of Portuguese territory, as it is a territory that, in addition to having an occupational history that dates back to ancient prehistory, is characterised by a diversity of river basins and a relief that presents a great variety of forms, but which has nevertheless historically faced various challenges related to the supply of water to its urban centres. Likewise, in order to be able to attest to the fact that the lack of water was a common shortage in the overwhelming majority of urban societies in the past, we will chronologically base our approach between Roman times and the Modern Age, necessarily taking into account the different historical and cultural contexts of the examples presented, as well as the water resources they had, which is why we have structured our presentation in three parts. The first is dedicated to water supply requirements in roman cities, the second to the analysis of continuities and ruptures in the supply of water to the medieval city and third to the main challenges facing modern cities in the field of hydraulic construction. Finally, in the concluding remarks we reflect on the different solutions found, but also on the changes that have occurred in construction solutions, their diffusion and/or rehabilitation throughout history.