Analysis of the spatial distribution of geohazards along the middle segment of the eastern margin of the Qinghai-Tibet Plateau

Abstract：By using the existing data of landslides obtained in the survey, combined with the field observations, this paper presents the results of statistical analysis of such parameters as elevations, slopes and heights of the landslides documented along the upper reaches of the Minjiang, Dadu and Anning rivers on the western Sichuan Plateau and makes a comparative study of these statistical results and the geomorphological features of deep-cutting river valleys. Study shows that the majority of the landslides occurred at elevations of 1 500-2 000 m above sea level along the upper Minjiang River valley and the Anning River valley, while the landslides in the Dadu River valley mainly occurred at elevations of 1 000-1 500 m and 1 500-2 000 m. The slopes of the landslides in these areas range between 15°and 35° but 45.21% of the landslides in the Minjiang River valley took place on slopes of 35°- 55°. The landslides of the Dadu and Anning river valleys mainly occurred on slopes of 15°and 45°. It is pointed out that the great majority of the landslides on the western Sichuan Plateau occur in deep-incised “V”-shaped valleys and are mainly controlled by the morphological features of the river valleys. The Late Quaternary rapid uplift and deep incision of valleys are two main internal dynamic factors for controlling the occurrence and distribution of geohazards on the eastern margin of the eastern Qinghai-Tibet Plateau.