The information method principle was applied in the mathematical evaluation model of landslide erosion.The first step of it was to analyze the factors affecting landslide process

and determine the main factors by calculating and comparing their contributions to landslide erosion.After section division for the research region

the second step was to summarize the information of selected factors to reflect the degree of landslide erosion on each section

and then set up a quantitative evaluation model for landslide erosion

which was applied for landslide erosion evaluation in Tongchuan City.Results indicated that in the research region of 82.5 km2

the area of highly intensive erosion was 13.0 km2

accounting for 15.76% of the total;the area of intensive erosion was 20.0 km2

accounting for 21.24% of the total;the area of moderate erosion was 25.25 km2

accounting for 30.61% of the total;the area of light erosion was 6.0 km2

accounting for 7.27% of the total;and the area of slight erosion was 18.25 km2

accounting for 22.12% of the total.Thus the area of landslide erosion above middle class was 58.25 km2

accounting for 70.61% of the total area

which implies that landslide erosion in Tongchuan City is serious.