This book is a very welcome addition to the study of Roman hydraulics, especially since it focuses on one aspect of Roman water management that has hardly received the attention it deserves: irrigation. The study of aqueducts, fountains, baths, and other elements related to water use in urban contexts has been the subject of an extensive (and growing) literature, but the use of water for other purposes in the Roman period has received until fairly recently very little attention. Current projects to assess water consumption in production processes and on the Roman economy as a whole have looked at other ‘industrial’ uses of water, but the rural management and distribution of water in agricultural contexts is still the great understudied topic. Willi’s book itself is an extended version of her doctoral thesis (Zürich, 2016), and despite the limits imposed by the recent sequence of lockdowns, it is bibliographically up-to-date and overall well-informed, covering a wide range of materials for the regions under study.
The book is structured into seven different chapters: a detailed introduction to irrigation and its studies (ch. 1), a brief outline of the archaeological evidence for the Western provinces (ch. 2), an analysis on the Latin vocabulary related to irrigation (ch. 3), a discussion of the way irrigation as a practice was discussed in the sources (ch. 4), an analysis of known legislation (ch. 5), a survey of specific case-studies of local water laws (ch. 6), and an overarching concluding chapter (ch. 7). These are followed by two appendices that tabulate references and terminology, a bibliography, and a detailed and useful index. The book is illustrated throughout in black and white, although a general map of the mentioned sites and known irrigation systems of Roman date would have been welcome.
The introduction does a fantastic job in presenting the topic: irrigation has always been a large enterprise, regardless of the period, albeit one aimed solely at maximising and intensifying agricultural production. Irrigation was not simply used to water fields (i.e., correct soil humidity), but it was a way of further disseminating nutrients and to wash away accumulated salts. Irrigation always improves the output and had a necessary impact on the economy—one which for the Roman period in general (and for the West in particular) has been largely overlooked. Willi thoroughly uses The Corrupting Sea as an interpretive starting point to underline the necessity in the Ancient Mediterranean to maximise agricultural output, for which irrigation necessarily had to play a key role.
Chapter 2 deals with the archaeological evidence. Willi did not write the book as an archaeological gazetteer, nor are her arguments based on watering-network analyses and other fully-archaeological approaches to the topic (as she underlines in the introduction, her thesis is on the social and economic aspects that can be derived from the sources), but physical remains are not ignored. This chapter does a good job at outlining the basics on ancient hydraulic engineering (dams, reservoirs, gravity flows, channels and conduit technology, water lifting devices), and it also gives an overview on the remains known from the Western Provinces, including Italy, Gaul, and Britain. The emphasis however is heaviest on the Iberian Peninsula, probably due to the author’s long collaboration with M. Beltrán. Hispania is presented as an exemplary case study to assess the relationship between Roman settlement (‘Romanisation’) and the implementation of intensive irrigation systems at both the local and the regional scale, while also highlighting the limitations of these approaches, such as the problems derived from not knowing what crops were watered in each particular example, or how much overflow was used/reused/managed.
Chapters 3 and 4 deal with irrigation in the literary sources. The former focuses on the language of irrigation itself, on the etymologies of the various words related to irrigation, and on the implications of these choices, but also explaining the extended use of this language that equates irrigation with victory over nature (domesticating waters and modifying landscapes) and with civilisation. The latter is a more detailed analysis of the agronomists’ works, considering important Roman writers of technical treatises (Cato, Varro, Columella), to other authors (Pliny, Cicero, Strabo), and poets (Vergil). This chapter goes into greater detail by analysing the more practical ways in which these writers discussed irrigation, their recommendations for water management on rural estates and the wide variety of crops that benefitted from watering; from meadows to cereals, including legumes, vines, all sorts of trees, plants used for their fibres, and vegetables and herbs kept in smaller patches.
Chapters 5 and 6 deal with the legal side of irrigation, discussing all the water laws that have come down to us (chapter 6 is, moreover, a detailed commentary on all the local laws known through inscriptions). The chapters survey how Roman water legislation in general was focused on regulating water rights and infrastructure, determining who was allowed to use public and private waters, under which conditions, who was responsible for it’s use once built, and how to deal with abuses. It is clear that public waters were managed by municipal authorities, and those people who wanted to irrigate their fields but had no access to private sources of water could purchase the right to public water. Such was the connection between the public administration and the need for irrigation that most rural grids associated with land distribution and settlement already were designed with irrigation/moisture regulation in mind.
The last chapter offers a series of conclusions that highlight again the importance of irrigation for the Roman countryside, as the author emphasises that irrigation was a key element in the Roman economy from the mid-Republican period onwards, and that the legal framework to regulate and protect rural water use reflect the key role it had at local and regional levels. The book underlines how irrigation was common and widespread in the Roman West, despite preconceptions and out-dated ideas, and that agricultural water management was a central aspect in the Roman rural life.
Overall, the book is clearly written, the arguments are well laid out and substantiated. The evidence that is presented is always relevant to the discussion and analysed thoroughly, to that it is not only neatly presented but put in the context of the relevant, ongoing debates on ancient economies. The book also gives an extensive and comprehensive explanation of Roman water law and links it to the agricultural practices that are described in Latin texts managing while also bringing in the relevant archaeological examples. It is, perhaps, regrettable that North Africa (or, at least, the Maghreb, from Tunisia to Morocco) was not considered as part of the archaeological study in more detail, especially since the laws of Lambasa (CIL VIII 4440 = 18587) are included and discussed throughout the text. This inclusion would have provided a broader western perspective and would have added more nuance on the irrigation practices along the coastal Mediterranean regions vs inland systems, north and south, that would have fitted nicely into the interconnected micro-region approach that was underlined in the introduction. But despite this, and in conclusion, the book is a great addition to the study of Roman archaeology and hydraulics. It gives a comprehensive overview of water legislation and Roman irrigation practices, whilst also underlining the available evidence for (and the extent of the practices through) Western Europe, which has usually been understated or underestimated in favour of the more evident information known for Egypt and the East. Willi’s book will be a point of reference for anyone working on Roman irrigation for years to come.
 Like the Granada AQUAROLE project.
 E.g., the Oxford Roman Economy Project .