Paleoflood history of the lower Verde River, Yavapai County central Arizona

A comprehensive analysis of slack-water flood deposits on the lower Verde River, Arizona, reconstructs the history of the largest floods on the river over the last 1600 years. The record provides unique information about the magnitude and frequency of extreme floods in the late Holocene and places its short historical record into its appropriate long-term context. The investigation was performed in a tributary mouth that is deeply backflooded during Verde River floods and it provides important insights into a variety of uncertainties that combine to preclude confident compilation of complete records of paleofloods in typical bedrock canyon slack-water settings. There are numerous processes that act over time to compromise the integrity of paleoflood stratigraphy. Most importantly, vertical accretion that has occurred in most slackwater sequences ensures that the stratigraphic record is progressively self-censoring and biased towards larger and younger floods. Uncertainty in event and temporal resolution of paleoflood slack-water stratigraphy should be explicitly addressed in fluvial paleoflood studies, and subsequent interpretations of paleoflood data in the context of flood-frequency analysis and paleoenvironmental need to account for them.