A.D. 458-1400 HOHOKAM 'S CANALS IN PHOENIX

From approximately A.D. 450-1400, a Native American group known today as the Hohokam overcame a harsh desert environment along with periodic droughts and floods to settle and farm much of modern Arizona. They managed this feat by collectively maintaining an extensive infrastructure of canals with collaborative labor.

New archaeological excavations by Desert Archaeology, Inc., carried out in advance of land development north of Phoenix’s Sky Harbor airport, resulted in a detailed new look at the repair and maintenance of two Hohokam canals fed by the neighboring Salt River. The research was published in the most recent issue of the Journal of Field Archaeology by Drs. Gary Huckleberry, T. Kathleen Henderson and Paul R. Hanson.

The excavations of these canal systems revealed a complex record of sedimentation that required substantial analysis to both delineate the evidence for major flooding and to determine when that flooding occurred. In his previous research, Huckleberry has investigated sedimentation patterns found in modern canal systems that can be directly tied to historically documented floods, thereby creating a strong comparative dataset to identify flooding in prehistoric contexts. The sediments found in the Hohokam canals excavated by Desert Archaeology, Inc., showed all the signs of poorly sorted sandy deposits and clasts of fine-grained material mixed by turbulent flows that Huckleberry had seen in historic contexts.

The archaeology team was able to date the Hohokam canals and flooding events based on a combination of classic and novel archaeological methods. Previous research in the region had relied on the stylistic analysis of pottery found in association with the canals to provide an approximate date for their use. The new excavations, however, were able to employ optically stimulated luminescence dating methods that reveal how long-ago quartz sand particles were heated by the fiery desert sun. With this new dating technique, the researchers were able to identify three distinct damaging floods that occurred between A.D. 1000 and 1400.

After each flood the Native American communities that relied upon the canal system to irrigate their fields banded together to repair the canal intakes, clear the channels of accumulated sediments, and repair canal walls and berms. Responding to disasters, however, strains social systems, even in the best of times.