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Captured evidences of debris flows declare the obvious changes of mudflow regime in the West Sayan midland and lowland areas and require the need to review the levels of regional hazard risk. The analysis of natural and man-made preconditions of debris flows increasing revealed the priority impact of the last ones. The absence of meaningful deviations from the normal of precipitation intensity targets was identified. It has been found that small debris flows on the middle grade of steepness slopes are a result of the combined activity of the different economic activities. Surface mining, associated road construction work, forming considerable amount of free of loose material, and active logging as well all contribute to emergence of debris flows hazard in basins of small rivers. The disruption of plant cover stabilizing role lead to the intensification of slope erosion processes. Taiga belt degradation was caused mainly by the large logging lasted in the region more than half a century. It is shown, that a slight decrease in the general forest cover has led to a serious changes of forest structure, which affects the intensity of slope erosion processes and increase in the sediment loads in rivers for several decades. A comprehensive approach to identify potential hotbeds of debris flows was proposed. It comprises the use of remote techniques in detection of human impact areas, morphometric analysis of watersheds affected by a large anthropogenic disturbance, assessment of areas under transformation, analysis of the temporal variability of hydro-meteorological characteristics and landscape structure dynamics. Due to the lack of availability of cadastral information of vegetation, soil and slope characteristics at an appropriate scale there is a need for more field research in key areas aimed at updating of the existing database.

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