BMCR 2007.09.18

Floods of the Tiber in Ancient Rome

, Floods of the Tiber in ancient Rome. Ancient society and history. Baltimore: Johns Hopkins University Press, 2006. 1 online resource (xviii, 338 pages) : illustrations, maps.. ISBN 9781435691902 $60.00.

Table of Contents

“In that year (189 BCE, there were great floods, with the Tiber flooding the Campus Martius and the flat areas of the city twelve times” (Livy 38.28.4: Aquae ingentes eo anno fuerunt, Tiberis duodeciens campum Martium planaque urbis inundavit).

In this latest addition to the Johns Hopkins Ancient Society and History series, Aldrete (A.) combines ancient literary and archaeological evidence with modern studies and data—ranging from hydrological studies of floods and how they work to modern human experience of floods and psychological responses to and trauma engendered by them—to create a fully contextualized picture of the Tiber river and its inundations of ancient Rome. Beyond assessing the impact floods had on Rome’s inhabitants, A. aims to understand why they never used their prodigious engineering and building skills to contain the river’s floods (unlike their modern counterparts, who built embankment walls between 1876 and 1910). His ultimate conclusion is that “…while floods were a frequent and destructive force and posed a potentially major thereat to the city, ancient Rome possessed a number of unique characteristics that made the city surprisingly resilient in coping with many of the negative affects of flooding.” (8) These characteristics, apparently, vitiated the need for full-scale control of the river.

In his introduction, A. considers floods throughout history, noting that while the regular floods of some rivers have proved beneficial to civilizations located along their banks, the inundations of others were shockingly devastating—modern comparisons are adduced—in terms of human and animal lives lost, and extremely costly in terms of property destroyed. This raises one of the main questions treated by A.: Why did the Romans build their city in a floodplain, and how did they cope with the flooding of the Tiber? His intent, he writes, is to focus not on how human-built urban landscapes impacted their natural environment, but on how nature (the Tiber) impacted the development of a human-made environment.

The book is divided into three main sections of two chapters each. The first section presents evidence for the varied characteristics of Tiberine floods in ancient Rome. Chapter 1, “Floods in Ancient Rome” (10-50), contains 42 passages from ancient literature referring to floods that occurred in Rome from 414 BCE to 398 CE (16-33). In addition to the evidence for the impact of and response to floods in Rome, these texts also provide important clues to the area such floods might cover through notices of important, well-known monuments that they reached. To assess which areas would have been affected by floods, A. maps floods of 10, 15 and 20 meters above sea level, onto a topographical map of Augustan Rome (Figs. 1.5-1.10), a period for which a relatively high number of literary references to floods exists.

In Chapter 2, “Characteristics of Floods” (51-90), A. uses hydrological graphs, models and maps of the Tiber and its drainage basin, and ancient and modern records of Tiberine deluges to extrapolate the duration, seasonality, frequency and magnitude of floods at Rome. He argues that the Tiber flooded Rome with far greater frequency than our sources indicate, perhaps because the floods deemed most worth reporting were those coinciding with important events, and thus considered portentous. (79) Thus, Livy’s (38.28.4) notice of twelve floods in one year (189 BCE) may not have been as anomalous as it might appear, at least not for the period from 200 BCE to 200 CE when the frequency and force of Tiber floods seems to have peaked. This apparent peak in reported flood activity, according to A., may have been due to Roman deforestation of the upper Tiber basin when Rome’s population—and its demand for housing materials—was also at its peak. He is careful to point out, however, that much of the evidence adduced is incomplete (a frequent disclaimer throughout the book), and that the impact of human activity on the environment, while verifiable, is unquantifiable.

In the second section, comprising Chapters 3 and 4, A. discusses the immediate and delayed effects of floods. Chapter 3, “Immediate Effects of Floods” (91-128), reconstructs “the effects of a ‘typical’ flood in ancient Rome and the problems and challenges…such an event would have created.” (91) Minor disruptions of daily life were met with ‘work around’ solutions, including alternate locations for scheduled rituals and games (79). A. insightfully demonstrates that flood damage may also explain Rome’s well-known problem of spontaneously collapsing insulae : those that did not crumple immediately under the impact of rushing water could have been weakened by prolonged exposure to flood waters—causing expansion, contraction and rotting of wooden supports, along with the disintegration of mud brick walls—then suddenly collapse weeks or months later. “In this way,” A. notes, “the inhabitants of Rome continued to be the victims of floods even long after the last pool of floodwater had dried up.” (131) Rome’s temples and public monuments, on the other hand, generally overbuilt and placed atop high podia, were virtually unaffected by floods. A. concludes with a graphic discussion of injuries, drownings and diseases caused by floods, as well as the post-flood clean up of water, sewage-infected sludge, debris of all sorts, and corpses. Those who contracted to “dry up floods” and “carry off corpses” (Juv. 3.32) could ill afford to be squeamish.

Chapter 4, “Delayed Effects of Floods” (129-165), revisits some of the material from the previous chapter, such as the long-term weakening of buildings or the spread of diseases caused by floods. Passing over the detailed and fascinating discussion of various bacteria, protozoa and tapeworms with which Romans could be infected, it is worth noting that A. contends that the post-flood morbidity and mortality rates in ancient Rome and environs would compare to those of cities in flood-prone, third world regions today, e.g., Bangladesh. (150-1) A. also explores the topic of post-flood food shortages and famines—often alleviated by imperial distributions of grain—and food spoilage, followed by a discussion of Rome’s massive grain-storage facilities themselves, the horrea. Although horrea were mostly located in areas prone to flooding, A. convincingly demonstrates that their vulnerability to flood damage was greatly decreased by their massively thick walls, the high placement of their windows and openings on outer walls, and their raised floors, which kept grain stores away from the damp earth below and above the level of moderate floods. These factors, A. contends, must have contributed to the apparent rarity of severe food shortages attributable to floods.

The penultimate section of this chapter, a discussion of post-flood psychological trauma sketchily constructed from modern evidence (154-160), is followed by a somewhat vague accounting of the “various government agencies and officials…involved in post-disaster rescue, cleanup and aid operations simply as an extension of their normal duties.” (163) This last statement is based on fairly reasonable assumptions, but little direct evidence (160-5). Indeed, the evidence adduced for private assistance to the victims of floods in Rome is unconvincing. A. refers to Tacitus’ account ( Ann. 4.63) of a temporary amphitheater’s collapse in Fidenae, five miles from Rome, in which 50,000 people—mostly visitors from Rome—were crushed to death or maimed. Tacitus reports that the great houses of the rich were thrown open to the victims, for whom doctors and aid were liberally provided. It is clear that the sudden and calamitous nature of this disaster impelled the rich to tender—and exceptional—acts of mercy; it does not necessarily follow that the same people would have thrown open their homes to Rome’s poor every time a flood drove them out of their insulae. Likewise, the evidence adduced for disaster relief provided by various emperors relates only to victims of catastrophic fires (Tac. Ann. 4.64, 6.45, 12.58; Dio 59.9.5). There is no compelling reason to extrapolate from these instances that emperors provided financial relief for flood victims. Indeed, the apparent absence from the sources of imperial benefactions related to flood damage in Rome may argue for the relatively minor impact flooding had, or was perceived to have had, on the city.

In the final section, Chapters 5 and 6, A. discusses Roman attempts to mitigate floods and how their attitudes towards the Tiber influenced their decisions about how to control it. Topping the list of Rome’s “Methods of Flood Control” (166-203) is its sewer/drainage system, including the Cloaca Maxima; the Petronia Amnis, which drained the central and southern Campus Martius; and various tributary sewers. It is unfortunate that A. did not go into more depth here and that his “Map showing some major Roman drains” (Fig. 5.3) fails to include most of the known sewer lines and drains dating to the imperial era. A. contends that the sewers’ unfortunate lack of backflow prevention devices was counterbalanced by Rome’s “continuous flow” water delivery system. The latter could wash the muck that gushed up from the sewers during a flood back down the drains with the overflow of its myriad fountains and spigots—along with the waste water of various thermae throughout the city—once the flood had receded. At the same time, this system—too high and too well protected from contamination to be affected by floods—continued to deliver fresh, clean water to Rome’s inhabitants. Other attempts at flood control included raising the ground level in flood-prone locations, various dredging projects and harbor embankments, and oversight committees established by the emperors, all of which A. discusses in detail.

In Chapter 6, “Roman Attitudes toward Floods” (204-231), A. considers why the Romans, who lacked neither expertise nor technology to deal with the Tiber’s inundations, chose not to safeguard the city more effectively. He avers at the close of Chapter 5 that “The answer to why the Romans did not do more to prevent flooding must be based on how they viewed the river in both practical and symbolic terms, and on the perceived costs, risks, and benefits of meddling with it.” (202-3) The ensuing discussions are uneven, at best, and make this chapter the least successful of the book. In the sections on how floods influenced the placement of public buildings and housing, and hence the physical development of the city itself, A. contends that imperial thermae built from 80 to 315 CE were placed well above Rome’s flood plain because the complicated piping of the thermae could not be subjected to the risk of flood-induced backwash. To counter different reasons for their placement on higher ground, A. offers a meandering defense of his theory, ending with an attractive suggestion, unsupported by direct evidence, that baths located on high ground could function as “emergency lodging” for Romans displaced by flooding. (209-211) The following discussion—on the hilltop location of most known domus (as opposed to the location of the vast majority of insulae in Rome’s valleys)—seems overly complicated both for its ultimate conclusion, and for the book’s intended audience. (211-217)

The sections on “Water and the Gods” (217-219), “Floods and the Gods: Portents and Divine Anger” (219-221) and “Flood Reports: Context and Causation” (221-225) are simultaneously tantalizing and frustrating because A. leaves this fascinating material largely underdeveloped. Regarding the Tiber as a portent or divine punishment, A. notes that a flood in 54 BCE “was interpreted as indicating the gods’ anger over Gabinius’s unauthorized restoration of Ptolemy to the throne of Egypt” (221; Dio 39.61.1-2) and that the flood of 27 BCE was interpreted by soothsayers as a sign that Augustus “would rise to great heights and hold the whole world under his sway.” (220; Dio 53.20.1) Both passages provide excellent opportunities to ask who politicized Tiberine flood events and why, or to explore the broader idea that political or financial expedient influenced religious attitudes and ideas about portentous Father Tiber, but A. simply moves on to the next suggestive item. We are thus left without a convincingly coherent argument about Roman attitudes regarding the Tiber and its floods.

In “Flood Prevention: Costs and Benefits” (225-231), A. speculates on unclear grounds that “those who ran Rome’s government” (and lived in hilltop villas) failed to alleviate the risk to marginalized peoples and businesses located in the flood plain for cynical, if not nefarious, reasons: “From the perspective of some of Rome’s elites, the destruction caused by floods in these neighborhoods could…have been perceived as a beneficial phenomenon. By literally washing away undesirable people and establishments, floods might be viewed as constituting a crude but effective form of urban renewal” (230-231). This suggestion ignores much of the interconnectedness between the classes and many of the elites whose political and economic well-being might depend—at least in part—on the very people and businesses at risk; it also ignores A.’s own discussion of the intermingled nature of many neighborhoods in the flood zone, wherein a small percentage of Rome’s elites, and many of Rome’s wealthier inhabitants lived cheek by jowl with its poorer working citizens. Strangely, unsupported speculation becomes fact a few pages later, when A. asserts that “[a] relative lack of concern on the part of the state for the suffering of the primary victims of flooding coupled with the possibilities for urban renewal that could result from a flood’s destructiveness contributed to a lack of motivation for the Romans in charge to take decisive action.” (238)

In the concluding chapter, “The Romans’ Failure to Make Rome Safe from Floods” (232-239), A. recapitulates his previous findings and concludes that the Romans probably did not undertake a comprehensive flood-prevention program because of factors that contributed to Rome’s resilience in the face of floods: its topography, providing convenient refuge points for victims (233); concrete, brick and marble structures built from public moneys or by elites were virtually impervious to flood damage (233-5); the decision-making elite did not have to live in the flood zone (235); the horrea and the grain stores were virtually impermeable to all but the worst floods (235-6); the continuous-flow water supply was not subject to interruption or contamination by flood (236-7); and the large-capacity sewers carried off most of the flood water quite rapidly once the flood itself had receded. Collectively, these factors do seem to have been enough to convince Roman leaders that containing the Tiber between unbroken stone embankments would have been a misuse of money and manpower; and, as A. suggests, religious scruples coupled with Rome’s overall resilience to floods might have left Roman leaders ambivalent towards Tiber-containment projects.

Despite the weaknesses of the last chapter, A. has impressively conveyed the full and often devastating impact floods had on ancient Rome and its inhabitants, and convincingly demonstrates which factors helped Rome recover rapidly from floods. This project succeeds in large part due to A.’s skilful handling of a wide array of ancient and modern evidence. There are, as noted above, some instances in which hypotheses are overstated or unsupported speculation becomes fact, but these are infrequent, and in the end detract little from the overall project. There is also a moderate amount of repetition in the later chapters; casual readers will appreciate this repetition, as it eliminates the need to flip back and forth through the book. Scholars will find much of value not only in the extensive bibliography, but also in the copious endnotes where some of A.’s best evidence and discussions are located. I found very few errors in the main text, most notably the use of Interamnate instead of Interamna (186), comparanda instead of comparandum (150), and equites (plur. nom.) where eques (sing. nom.) is surely meant (164).

A. has produced a comprehensive, insightful and lucid book-length study on a topic of great importance to anyone who wishes to comprehend the realities of life in ancient Rome or how the Tiber influenced Rome’s development. The overall production is also of a high standard, with beautifully reproduced photographs, maps and charts. Floods of the Tiber in Ancient Rome is sure to be a standard work in the field for many years to come, one that those working on Rome’s urban topography or daily life must include among their essential readings.