關鍵字:沖積扇、基準水面、頂積層坡度、輸砂濃度 ;The depositional process of debris-flow fans is experimentally explored in this study. The fan slopes were controlled by particle sizes, sediment concentration(i.e., the ratio of sediment discharge (Q_S) to water discharge (Q_W)) and the base-level water depth. Both longitudinal and cross-sectional profiles of alluvial fans were simultaneously measured by using a digital camera, a reflection mirror and multi-laser settings. The top-set angles increases with the increasing sediment concentration, while decreases with the increasing base-level water depth. The longitudinal profile of the alluvial fan is concave when the base-level water is negligible. While the longitudinal profiles become linear, a milder slope for topset and a steeper one for the foreset, when the base-level water exists. The dimensionless cross-sectional profiles show self-similarity characteristics.
Key words: alluvial fans, base level, top-set slope, sediment concentration.