The material supply ability analysis of debris flows based on area-hypsometric integral and area-gradient integral

Abstract

The loose material is produced by erosion and evolution of basins. The material supply ability affects the susceptibility degree and activity frequency of debris flow for debris flow basins. Taking 147 debris flow basins as a case, located in parts of Dujiangyan and Wenchuan, using the area-hypsometric integral and the area-gradient integral, the geomorphologic evolution stage and erosion intensity were quantified. Combined with the geomorphologic evolution stage and erosion intensity, the material supply ability analysis of debris flows was carried out. The results are as follows: it is not enough to explain the susceptibility degree only with the geomorphologic evolution stage or erosion intensity; the outbreaks of debris flow are mainly concentrating on the stage of maturity, maturity partial youth age and the erosion intensity Ⅲ—Ⅴ level; with the improvement of the material supply ability, the outbreak rate of debris flow increases, and the basin area plays a significant role in limiting the formation of debris flow; for medium, strong, and extremely strong supply ability levels, debris flow preponderant development area ranges are: 20—35, 10—50, 10—40 km2 respectively, in the study area; the investigation of material reserve and distribution should be carried out on the basin, which with a high level of material supply ability and in the optimal range of area and with unapparent debris flow activity for a long time, to confirm the stability of debris flow and formulate disaster control plans reasonably.

Keywords

• debris flow
• area-hypsometric integral
• erosion intensity
• material supply ability