Evaluation of a method to calculate debris-flow volume based on observations of flow depth

The volume of a debris flow is critical parameter in hazard analysis, yet accurate estimates are often unavailable due to mixing with larger rivers at the downstream end alluvial fans. We describe method calculate flows using depth data collected check dam, Manning friction relation velocity as function depth, and geometry channel cross section. evaluated published set from USGS debris-flow flume where event stage information have been accurately measured, results either somewhat smaller than or up 50% observed volumes. further demonstrate single-surge multiple-surge Illgraben.