Abstract: The influence of river knickpoint on the distribution of geological hazards in river basin was analyzed quantitatively using the hypsometric integral (HI) method. First of all, the correlation between HI values and landslide density in the central Himalayas and the Qingyi River basin was calculated using ArcGIS and MatLab software; subsequently the causes of knickpoints of the Yarlung Zangbo River, the Indus River, the Boqu River, Majiazangbo River, the Pengqu-Arun River and the Kali-Gandaki River in the Himalayas region were analyzed; finally the HI values of watersheds within the knickpoints’ upstream and downstream areas of all the rivers were calculated. The results are concluded as follows: (1) the HI value is in a good positive correlation with landslide density, with all correlation coefficients greater than 0.5; (2) the HI value in the upstream basin of knickpoint is smaller than that in the downstream basin, indicating that the overall stability of upstream river basin is stronger than that of downstream; (3) for knickpoint of tectonic origin, the HI values of downstream and upstream river basins are quite different (the minimum is 0.06), while for knickpoint of river blocking origin, the difference of HI values between upstream and downstream is small (the maximum is 0.02). The results provide a reference for macroscopically and quantitatively determining the stability of valley slope.

Key words: knickpoint, stability of valley slope, hypsometric integral, Tibetan Plateau, landscape revolution, landslide