Response Of Debris Flow Activity Area To Change Of Arid Valleys Area In The Upper Of Min River

The arid valley of the upper Min River reaches is a typical landform that due to its unique landform and climate factors.Meanwhile,the arid valley is a typical mountainous eco-environmental fragile area and a mountainous disaster-prone area reaches of the upper Min River.For a long time,there is no unified definition in the dry valley.The accuracy of the extraction method in the arid valley is relatively rough.This paper defines the arid valley as the area where there is no vegetation or less vegetation in the valley,after synthesizing expert experience in various fields.Based on this definition,using RS and GIS technology.Defines the boundary of the dry valley in the upper reaches of the Min jiang River,and using GIS spatial analysis technology to analyze the boundary fluctuating state in the arid valley.After the "5.12" Wen chuan earthquake,the ecological environment of the upper Min River has further deteriorated,and the area of the arid valley has changed,and increased number of debris flows.However,the boundary fluctuations in arid valleys are not the main cause of landslide disasters,but indirectly affecting the reserves of debris flow sources.Based on this,the paper comprehensively uses cross-disciplines to explore the laws of arid valleys and debris flows based on the study of the engineering geological background and the ecological environment.The main progress and conclusions are as follows:(1)Based on previous research and research results,the 2000(TM),2009(TM),and 2013(OLI)multi-band remote sensing imagery were selected as basic research data.The CRAT method was used to extract bare terrain classifications.The classified results were superimposed with Google Earth images to obtain th e final dry valley boundary.The classification results were evaluated well.(2)The data was further sorted,filtered,and vectorized to define the boun daries of the debris flow basin and form vector surface files.The number arid v alley of the upper Min River before the earthquake was 130.Among them,there are 15 in Wen chuan County,50 in Mao xian County,18 in Li County,15 in Hei shui County,32 in Song pan County,and 0 in Du jiang yan.The number of debris flows after the earthquake was 178,including 27 in Wen chuan County,70 in Mao xian County,25 in Li County,20 in Hei shui County,36 in Son g pan County,and 0 in Du jiang yan.(3)In the study area,2005 and 2009 were selected as the boundaries the arid valley of the upper Min River reaches of the after the earthquake.The rese arch on debris flow activity has two aspects.One is the distribution of debris fl ow disasters in dry valleys under different factors such as elevation and slope,a nd the other is using AHP to assess the risk of debris flow in dry river valleys.through analysis,it was found in the debris flow ditch near the fault zone.Acco rding to the analysis,the seismic energy is huge.In the debris flow ditch near t he fault zone,the increase of the area of the dry valley provides a rich material source for the debris flow.However,in the debris flow channel far from the fa ult zone,the seismic energy is not fully dominant,and the degree of the formati on of debris flow disasters in different channels is widely divergent.(4)Based on the analysis of previous research results,using GIS spatial a nalysis technology that analyze a response relationship between debris flow activi ty and area change of dry valley was analyzed from the perspectives of distribut ion area,elevation and slope.(5)Through spatial fractal theory in the arid valley research area,the frac tal dimensions obtained were 1.7601 and 1.78,respectively,with a difference of0.0199.Itshows that the fractal dimension of the spatial distribution of the debris flow channel has changed.The general trend is that the debris flow area increas es rapidly and the fractal dimension increases.The arid valley has a greater imp act on the formation of debris flow.(6)According to the response of the debris flow area of the upper Min R iver to the change of the arid valley area,the avoidance and control measures f or the arid valley and debris flow disasters were proposed.