Current evidence suggests that Indigenous farmers in the North American Southwest began canal irrigation in the second millennium BC, marking an important change in food production technology. Early canal systems are preserved in alluvial floodplains of the US-Mexico Borderlands region, tend to be deeply buried, and can appear as natural fluvial features. Here I discuss some of the challenges in identifying early canals and associated fields and present case studies from the Santa Cruz River in southern Arizona where buried channels dating as early as 1600–1400 BC were likely human constructed. These small channels share several stratigraphic properties and are consistent with hypotheses of early canal irrigation practiced by small family groups reliant on mixed farming and foraging. Through time, irrigation canal systems expanded in size, resulting in increased labor investment, sedentism, and productivity and facilitating the development of larger irrigation communities. Stratigraphic and geomorphic properties of early canal systems thus far identified along the Santa Cruz River provide a framework for identifying potential early canal evidence in other fine-grained floodplains of the Southwest, thereby improving our understanding of Indigenous agricultural intensification.

目前的证据表明，北美西南部的土著农民在公元前二千年就开始进行运河灌溉，标志着粮食生产技术的重要变化。早期的运河系统保存在美国-墨西哥边境地区的冲积洪泛区，往往埋藏较深，可以作为自然河流特征出现。在这里，我讨论了识别早期运河和相关领域的一些挑战，并介绍了亚利桑那州南部圣克鲁斯河的案例研究，那里的埋藏河道早在公元前 1600 年至公元前 1400 年很可能是人类建造的。这些小河道具有多种地层特征，并且与依赖混合耕作和觅食的小家庭群体进行早期运河灌溉的假设相一致。随着时间的推移，灌溉渠系统的规模不断扩大，导致劳动力投资、定居和生产力增加，并促进了更大的灌溉社区的发展。迄今为止在圣克鲁斯河沿岸发现的早期运河系统的地层和地貌特征为识别西南其他细粒洪泛区潜在的早期运河证据提供了一个框架，从而提高了我们对土著农业集约化的理解。