This chapter presents a method by which morphometric criteria can be used to obtain a rapid first-approximation of potential debris flow hazard on alluvial fans in the Canadian Rocky Mountain Front Ranges. Geomorphic and sedimentologic evidence indicates that many fans are affected by debris flow processes. Such fans generally are steeper than 4° and have small, steep first- or second-order drainage basins with Melton’s ruggedness number (R) more than 0.25 to 0.3. Fans not prone to debris flows are dominated by fluvial processes and have gentler slopes in less rugged third-order or higher drainage basins. This morphometric approach should have wide applicability for continuously graded basins in unglacierized regions.
Figures & Tables
Debris flows and debris avalanches are among the most dangerous and destructive natural hazards that affect humans. They claim hundreds of lives and millions of dollars in property loss every year. The past two decades have produced much new scientific and engineering understanding of these occurrences and have led to new methods for mitigating the loss of life and property. These 17 papers pull together much of this recent research and present it in these categories: (1) process, (2) recognition, and (3) mitigation. Much of this work results from cooperative efforts between GSA's Engineering Geology Division and Quaternary Geology & Geomorphology Division.