Floods of the Tiber in Ancient Rome

Conclusion

232 Conclusion The Romans’ Failure to Make Rome Safe from Floods ∫ loods were indeed a serious problem for ancient Rome. Rome eventually grew into an enormous, architecturally complex city, but this densely populated, man-made urban landscape was situated on ground that was inherently marshy. Even worse, the city was located squarely in a flood plain and, in fact, had the misfortune to be positioned at the very point on the Tiber most prone to severe flooding. As this book has argued, these floods were far more frequent than has traditionally been assumed , with minor inundations taking place every four or five years, and catastrophic ones striking on average every 20–25 years. The latter could be of impressive magnitude, with their waters rising 15 m above the normal level of the river and inundating large regions of the city. As has been described, floods caused a wide range of both immediate and long-term destructive effects, including disruption of urban daily life, death of humans and livestock, the collapse of buildings , and increased incidence of disease. The Romans witnessed firsthand the harmful effects of floods and knew with a high degree of probability that these disasters would recur. Given all these facts, the question remains: why did they not do more to prevent these floods? One way to begin explaining this failure is to perform an overall assessment of ancient Rome’s vulnerability to floods in light of the in- formation that has been presented in this book. Such a comprehensive evaluation reveals that the city possessed a number of unusual or even unique qualities that reduced its vulnerability to floods, rendered Rome and its inhabitants less susceptible to the damages produced by floods, and made the city atypically quick to recover from the effects of an inundation. There are at least five characteristics that helped to minimize Rome’s vulnerability to floods: topography, construction methods , residential housing patterns, food storage, and water supply. Topography. The highly varied topography of Rome intermingles within a constricted area several low-lying valleys and marshy depressions together with numerous small hills. Rome is famously the city of seven hills, and their presence would have been a major factor in reducing the fatalities that resulted from flooding. Not only do lines of hills surround the central area of the ancient city, but a number of escarpments are also scattered throughout the city’s core. These would have provided convenient points of refuge to which the inhabitants of the city could have fled. Almost every point within the Aurelianic walls is less than a few hundred meters from high ground; even if someone were in the center of the Campus Martius, sanctuary on a hill was little more than a kilometer distant. Although relatively small, the hills of Rome tend to have fairly steep slopes, so that a person fleeing floodwaters could have quickly climbed to an elevation that was safe. Thus, while one was never far from the danger posed by the Tiber, one was also never far from reaching safety on a hill. The two situations that tend to result in large numbers of deaths are floodwaters that rise very rapidly, such as flash floods, and floods that strike in a flat terrain that offers nowhere to run to. The latter are common in China, where appalling death tolls are routinely caused by flooding of the Hwang He (Yellow) and Yangtze (Chang) rivers, which flow through vast, featureless plains that supply no points of refuge when the waters rise.1 At Rome, on the other hand, the proximity of numerous hills offered ready sanctuary from floodwaters, and while the level of the Tiber can rise rapidly, such increases are measured in hours rather than minutes, allowing time for the city’s inhabitants to reach high ground.2 Construction Methods. At first glance, it seems odd that the Romans erected the majority of their important public buildings in a flood zone. However, while some Roman construction materials, such as 233 The Failure to Make Rome Safe from Floods sun-dried brick, were highly susceptible to damage by water, major public monuments were typically built using materials and methods that rendered them invulnerable to destruction by floods. Floods usually cause serious damage to buildings either by undermining their foundations or because structural components are made out of materials that can be harmed by immersion in water. However, important buildings such as temples...