RESEARCH ON DEVELOPMENT AND DISTRIBUTION RULES OF LARGE-SCALE LANDSLIDES IN BAILONGJIANG RIVER BASIN

After filed investigation and interpretation of remote-sensing images, 259 large-scale landslides have been obtained, and general distribution situation of large-scale landslides has been learnt. Then, the distribution of these large-scale landslides is investigated statistically using GIS techniques to determine the correlations between the occurrence of large-scale landslides and the distance from the fault, elevation and rock group type. The main results are summarized as follows:(1)The large-scale landslides show the feature of zonal distribution along the fault and linear distribution along the rivers. (2)More than 90% of the large-scale landslides are distributed within the range of 5.0 km from the fault, and the farther from the fault, the lower number of large-scale landslides. At the same time, the large-scale landslides are mainly distributed in the zones closely related with the crossing, staggering and transforming section of the fault. (3)The large-scale landslides have corresponding relationship with the elevation and micro-landform. Most large-scale landslides occur in river valley and canyon section below the elevation of 1200 to 2600 m(upstream is 2200 to 2600 m, midstream is 1600 to 2200 m, downstream is 1200 to 1600 m), particularly in the upper segment of canyon section. (4)The soft and hard stratified rock group in the basin is most favorable for the development of large-scale landslides. More than 93% of the large-scale landslides are associated with phyllite and slate metamorphic rocks.(5)The main sliding directions are the NE and W. But it shows the same characteristics as the strike of the fault, namely SE and NW oriented in Liangshui, Wudu to Lazikou, Zhouqu.(6)The sliding distances of the large-scale landslides are related to the volume of the landslide. As the landslide volume increases, the friction coefficient of the large-scale landslides decreases exponentially. Some large-scale landslides show strong debris flow characteristics.