In this book, Charles Ortloff explores the technologies of hydraulic engineering projects of the pre-modern societies of the Andean world, the Mediterranean basin, and southeast Asia. Ortloff is a noted mechanical engineer who has collaborated on a number of archaeological projects that investigate water-infrastructure projects, especially in South America. His work in the Andes, the Middle East, and Asia over the decades was presented in 2009 in his first monograph, which, like the book under review, applied Computational Fluid Dynamics (CFD) models to ancient structures in order to understand the engineering principles underlying their construction. Now he expands upon that work, using CFD models and mathematical theories to argue that water-infrastructure projects were integral to state formation, postulating as well that ancient societies were capable of attaining the same results in their projects that modern hydraulic engineering has achieved.
The book is divided into three sections, each focused on a discrete geographical area. The first, on pre-Columbian Peru and Bolivia, is by far the longest (nearly 260 pages), with seven chapters. In his exploration of the development of the numerous societies in this region, Ortloff uses water-infrastructure projects as evidence of growing complexity in the process of state formation. Chapter 1 utilizes Complexity Theory, a system of mathematical equations that can predict specialization and societal development, to show how the societies of the region developed into elite-ruled groups that promoted cooperation by the populace, a process most easily recognizable among the Inka. The complex infrastructure systems that developed, Ortloff argues, went hand-in-hand with a more complex social structure, in which people worked together to reap collective economic and security benefits. In Chapter 2, Ortloff employs Similitude Theory to examine the use of land, water, labor, and technology in order to understand whether these societies were able to use their resources optimally. He shows that strategies related to agricultural cultivation (and thus tied to irrigation projects) fostered the development of complex systems, including raised field systems that could withstand the changes in climate (especially drought or flood events) that are known to have occurred in the region. Chapter 3 explores 25 adaptive hydraulic engineering strategies used by the societies of the Andes in response to climatic and weather variations (e.g., the construction of intervalley canal systems during intense climate events). Then, in Chapter 4, Ortloff uses a sustainability factor equation to quantify the impact of these strategies on the societies in question. Such modeling reveals vulnerabilities in each of these strategies and their impact on a group’s collapse or survival, especially during the droughts that plagued the region in the 7th century CE and again in the 11th century.
The final three chapters of this section present case studies that apply CDF models to the investigation of the engineering principles behind water projects at different sites. Chapter 5 explores the canals of the main city of the Tiwanaku (Bolivia, active 300-1100), where the models suggest that the water management offered hygienic benefits for the population, establishing an efficient flow through the site, thus reducing dampness, for example, which can have adverse health effects. Chapter 6 investigates the fountains and aqueducts of the Inkan site of Tipon (Peru, active ca. 1400-1530s), where the engineers were able to control the flow of water (including velocity, rate, etc.) from multiple sources effectively, which allowed them not only to deliver water to the site safely, but also to create aesthetic effects, including waterfalls in the principal fountain there. Finally, Chapter 7 documents how the site of Caral (Peru, active 2600-1800 BCE) responded to drought and flooding events that effectively silted the site up along its coast, thus illustrating the impact of such events on the population—and how they developed strategies to respond to them.
The second section of the book looks to the Mediterranean world. Chapter 8 presents CDF models from Petra (Jordan, 100 BCE-300 CE), which demonstrate the complexity of designing water-infrastructure systems in this arid area. Through models that allow for a variety of scenarios in reconstructing water flow, Ortloff is able to determine the correct slopes of various pipelines (e.g., Wadi Mataha, Ain Braq), at the same time revealing the Nabatean engineers’ command of the complexities of hydraulic engineering. Chapter 9 examines the Pont du Gard aqueduct and its castellum, or water distribution tower, at Nemausus (Nîmes, France; inaugurated under Claudius). Through CDF modeling of different rates of flow, Ortloff shows that the castellum, with its 13 pipeline holes, could provide residents with the necessary 40,000 m3 of water daily, which could then be diverted to areas of the town that required a more pressurized (or “critical”) flow (e.g., public water-displays, private homes) or less pressurized (or “near critical”) flow (e.g., gardens, latrines). In Chapter 10, Ortloff briefly demonstrates that Roman pipes that measured flow rates (calices) depended on induced turbulence resistance—meaning that the pipe’s nozzle was contracted on the interior to control flow. Finally, in Chapter 11, Ortloff offers observations on the hydraulic systems of Bronze Age Knossos, commenting on the hydrostatic pressures that the pipes of the palace had to attain in order to supply the various parts of the structure.
In the third section of the book, a single chapter provides an overview of canal projects constructed in China over the millennia, without any real comment on hydraulic principles. A final chapter (“Conclusions”) attempts to summarize the content of the previous chapters and to make connections across cultures across the globe. Influenced by Karl Wittfogel’s Oriental Despotism (1957), which holds that rulers of Asian societies relied on large-scale irrigation works to remain in power, Ortloff argues that Andean and Asian societies, were, in effect, hydraulic states, in that they were ruled by elites that used water-infrastructure projects to create and control societies. He also goes on to argue that the Roman empire was not a hydraulic state, because “these water systems were viewed by Roman administrators as necessary elements of a civilized society rather than key [sic] to power of the ruling elite,” (p. 356), which is a problematical assertion, given the roles of both the emperor and local elites in hydraulic benefactions and the actual construction of water-infrastructure networks across the Roman world.
This is an important book, building on Ortloff’s crucial work on the science of ancient hydraulic engineering and arguing for its importance in state formation and maintenance. Its global scope, however, presents problems. There is no general introduction to orient the reader within the three very different geographies explored here, and no real narrative thread to provide continuity throughout the text. In the first section, on the Andes, the lack of an introduction leaves readers unfamiliar with the complex histories of the societies of the area in the dark, which diminishes the important observations Ortloff makes (especially when he discusses the religious practices surrounding huaca stones). Most importantly, a general introduction would have provided the optimal venue to define the characteristics of the ‘hydraulic state’ of the book’s title. Instead, Ortloff delays such discussion until his final chapter, where he relies too much on Wittfogelian notions of elite-sponsored hydraulic projects. There is also a great deal of repetition throughout the volume, creating the impression of the book as a series of independent articles that were never fully integrated into a coherent work. Further, the organization of each section does not provide the reader with any clues to Ortloff’s train of thought (e.g., sections are not chronological). Ortloff’s 2009 monograph employed CFD models to great effect, which he expands here with new case studies. Chapters 1, 2, and 4 introduce new mathematical models to apply to examples of ancient engineering, but after that, these new methods are not employed again, or even mentioned, until the Conclusions; even then, there is no discussion of how we can effectively employ these models in other situations.
Further, problems with the production of the book seriously detract from its legibility and usability. Grammatical errors occur throughout the text, and many of the illustrations are of such poor quality that they are hard to read. In addition, a number of Ortloff’s CDF models should be in color for easy comprehensibility (as they are in the electronic version of the text); it is hard to discern the flows Ortloff has modeled in the black-and-white versions published in the print version. One figure (8.15a-c) was apparently cropped, as it shows only the first two CDF models described in the caption; in addition, in the text, the callouts for the figure give a confusing range of numbers (e.g., 8.1 6B; 8.6a; 8.7b; 8.7c). Finally there are some factual errors in the text related to historical details, presumably stemming from the wide-reaching span of the text—and the fact that one individual cannot be an expert in so many cultures across the globe. For example, Figure 11.4 is identified as the Roman aqueduct of Knossos, but it is in fact the modern aqueduct constructed there during the Egyptian rule of Crete, between 1830-1840 CE.
Despite these problems (some of which are attributable to the publisher), the importance of Ortloff’s contributions to our understanding of hydraulic engineering, whether in the present volume or elsewhere, is without question. Ortloff prompts us, as classical archaeologists, especially, to initiate new dialogues with hard scientists and other specialists. For example, Ortloff’s discussion of detecting responses to climate-change events has special resonances today—but also encourages us to reconsider other such historical events that may be visible in the archaeological record, including that of the Mediterranean basin. Such partnerships allow us to understand more precisely how the ancient world functioned, not only from a social-historical perspective, but also in light of the scientific underpinnings of those structures that were foundational to societies that enjoyed abundant flowing water.
 C.R. Ortloff, Water Engineering in the Ancient World: Archaeological and Climate Perspectives on Societies of Ancient South America, the Middle East, and South-East Asia (Oxford, 2009).
 E.g., Ortloff provides crucial background information only in Chapter 3, including a map of the area (Fig. 3.1, p. 115) and chronologies of the eight societies mentioned in the text (p. 141).
 E.g., there is a verbatim repetition of Inkan water terminologies (pp. 40 and 220), and some figures are repeated (e.g., 2.4/4.4; 3.6/7.5).
 Indeed, the contents of three of the chapters have appeared, nearly verbatim, in articles that appeared before and after the publication of this work. See: “Tipon: Insight into Inka Hydraulic Engineering Practice,” Latin American Antiquity30.4 (2019) 724-740, doi:10.1017/la.2019/70; “Hydraulic Engineering at 100 BC-AD 300 Nabataean Petra (Jordan),” Water 12 (2020) 3498, doi:10.3390/w12123498; “Water Engineering at Precolumbian AD 600-1100 Tiwanaku’s Urban Center (Bolivia),” Water 12 (2020) 3562, doi:10.3390/w12123562; “Roman Hydraulic Engineering: The Pont du Gard Aqueduct and Nemausus (Nîmes) Castellum,” Water 13 (2021) 54, doi:10.3390/w13010054.
 E.g., the quarter-page figure 8.1 is barely legible, even though it shows all of the monuments and topographical markers of the region of Petra.
 The reader should consult Ortloff’s article on Petra (supra), which includes the full illustration (in color), with correct callouts. The illustrations in the articles cited above are also of superior quality to those in this monograph.
 There are also further oddities in the chapter on Knossos, including questionable observations about the Hagia Triada sarcophagus (p. 330) and problems with Figures 11.9-11 and their callouts in the text.