Irrigation, Water Allocation Strategies, and the Hohokam Collapse

Abstract

ABSTRACTThis paper explores potential structural characteristics and archaeological indicators of two models of water allocation that may have been implemented by Hohokam groups in central Arizona. One model, termed “regulated competition.” presumes the existence of institutionalized regulatory mechanisms. The second model, termed “unregulated competition,” presumes no such mechanism. Unregulated competition better explains the occurrence of (1) high densities of canals and archaeological sites in upstream portions of the Salt River Basin that do not contain prime alluvial bottomland, and (2) nonoptimal canal gradients and changes in canal cross sections that allow water to be diverted rapidly from major drainages. A sequence of collapse among irrigation systems in different drainages is developed using the unregulated competition model of water allocation and earlier arguments concerning variations in stream flow between basins. When extended to their logical conclusions, these data imply that sites in t...