The Fractal Property Of Debris Flow Disaster

The road of G212 is a very important passage which links the northwest and southwest of our country. Longnan is one of the four areas where debris flow developed well. Debris flow disaster severely threatens the road's security; affect the development of economy and people's existence of the area. At the beginning of 1980s, fractal theory is gradually applied in the field of natural science such as geosciences, catastrophology and so on. And it will be widely used in the area of geological disaster such as debris flow in the future.The theme is sustained by the project of the west's traffic which provided by ministry of communications: the study of building techniques in Longnan segment of G212. Bases on the physiognomy characters which impacted the development of debris flow and according to the full-sectors, 6 drainage basin, 4 attributes, 3 development stages and 3 degrees of disaster with 232 pieces of debris flow gullies, the theme systematically analyzes the Longnan segment of G212 by fractal theory. Then three parameters of form munbers, terrain gradient and physiognomy statistical model have been calculated and compared. The main conclusions are as follows:1. Debris flow is probably happened where drainage area is less than 10km~2 , main gully length is less than 10km and average main gully slop is 10%～60%.2. The theme analyzes the significances of the division of physiognomy elements such as drainage area, main gully length average main gully slop and so on. Then it can conclude that drainage area is important to the form and development of debris flow, main gully length is less important and average main gully slop is the least important.3. The theme fractals physiognomy elements of 6 drainage basins of study area, compares and analyzes each fractal dimension and three parameters. The result is that where debris flow disaster develops best is Bailong drainage basins, then Mingjiang drainage basins and the least developed is Luotang drainage basins.4. By analyzing the 4 attributes, fractal dimension and parameters of debris flow gullies of 3 development stages it can conclude that the area where the dilute debris flow, the florescence of debris flows form is nearly round and viscous debris flows, developing debris flow are evidently impacted by physiognomy elements. 5. According to the water system fractal results of single ebris flow gullies it can find that debris flow of Niwan channel is active, then Hongtuwan channel and the least active one is Dongjiang channel.