Characteristics of Landslide Under the Extreme Rainstorm in 2013 in the Yanhe Basin

The extreme rainstorm occurred in Yanhe Basin in 2013,and triggered various landslides.According to Investigation Code of Landslide,Rockfall and Debris Flow(DD2008—02),we investigated landslides in six small watersheds in Yanhe Basin from north to south.The results showed that:(1)heavy rain and rainstorm mainly concentrated in July,Baota District was the central area of rainstorm in Yanhe Basin because its erosive rainfall was the greatest;(2)the erosion modulus of landslide of two watersheds which were farther from the central area of rainstorm in south were the largest,and reached to 7 000t/km2,it reached to 3 700t/km2 in central watersheds,and reached to 1 400t/km2 in northern watersheds,landslide amounts and landslide frequency also showed this law:southcenternorth;the landslides which were shallow landslides occurred in loess and distributed slopes of 20°~60°;all of landslides belonged to small scale landslide,the proportion of volume of landslides which were less than 1 000 m3 was the greatest and reached 78%,the number of landslides whose scale exceeded 5 000m3 was few.