ANALYSIS AND REVELATION OF GIANT DEBRIS FLOW HAZARDS OF AUGUST 18, 2010 IN GONGSHAN COUNTY,YUNNAN PROVINCE

The article is based on field survey, and data of remote sensing interpretation. It elaborates genetic mechanism and characteristics of Dongyuege river debris flow hazards. It analyses the geological environmental background. The terrain conditions are long distance, large gradient and narrow canyon and straight channel. It provides a powerful terrain condition for the occurrence of debris flow. There are a lot of loose deposits of upstream. They provide sufficient material sources for the occurrence of debris flow. The debris flow lasted 2273 second. The flow rate was 4.62ms-1.The seepage was 1008m3s-1.Mizoguchi formed in a length of about 300m, and a maximum width of about 400m of the alluvial fan. The total debris volume was about 60.5104m3. The total solid volume of a single event was of 41.95104m3. The fluid was thick paste. The fluid had straight and strong uplift force and had structural movement without vertical exchange. The fluid had obvious characteristics that drag reduction and showers movement. The debris flow density was 2.04gcm-3.It was a large viscous debris flow. The corners ultra of debris flow was quite obvious from mizoguchi 2.5km. Its height was 4.1m. The debris flow overall impact was 64.01kN.The single rock block maximum impact force was 491.27 tf. Dongyuege debris flow had the features of high drop, large gradient, narrow canyons, gross volume, high-speed, and long-distance. It also had a characteristic that was hidden, sudden and devastating. It is a typical high debris flow. Analysing the debris flow mechanism and movement characteristics can provide a scientific basis for the early identification, monitoring warning and risk evaluation of the entire Nujiang River Basin, as well as the southwest mountains and canyons area high debris flow.