Abstract: A debris flow physical model was established to study the starting-up characteristics， and then the initiation mode， recharge sources of provenance， the influence of rainfall on debris flow were studied. The results shows that the major provenance in debris flow forming area wont slide integrally when the debris flow starts up， but rather forming some gullies on the surface of the forming area， and the gullies develop until the debris flow starts up. It′s more dangerous in the case that the soil is saturated by small rainfall beforehand and then scoured by the moderate or heavy rainfalls. Unstable rock and soil mass on both sides of the gullies become the main recharge sources of provenance. The experimental results are well consistent with the natural Panlonggu debris flow. The research results can provide certain reference for building the early warning system and disaster prevention and reduction for Panlonggu debris flow and other similar debris flows.

Key words: debris flow, characteristics of initiation, artificial rainfall, gully, unstable rock and soil mass