County Scale Based On The Calculation Of Relief Degree Of Land Surface In Chongqing And Its Spatial Coupling Relationship With Landslide Disaster Frequency Research

Located at the front edge of China’s second echelon, occupying three tectonic units:the Daba mountain belt of folded strata, the eastern Sichuan belt of folded strata and theraised Sichuan-Hubei-Hunan belt of folded strata, Chongqing-the “mountain city”-hasa large surface fluctuation degree and fragmented terrain. Now as a municipality, withthe implementation of the China’s western development strategy and the formation ofthe Three Gorges reservoir area, etc. Chongqing will see a change on the Relief Degreeof Land Surface (RDLS), thus influencing the landslide disaster situation in the studiedarea. Hence, I chose Chongqing as the study area to explore the county-scale spatialcoupling relationship between Relief Degree of Land Surface and Landslide. This studycan not only help understanding the topographic undulationstatus in the studied area,thus providing effective guidance for the landslide disaster prevention and controlproject, but can offer powerful basis for regional economic development and resourceexploitation program in each districtand county of Chongqing. Below are the concreteresearch contents:(1) Based on1:250,000DEM data of Chongqing, using computational methodslike surface slope analysis, neighborhood analysis and hydrology analysis, the paperextracted six index factors including slope, relative elevation difference, surfaceroughness, gully density and valley density, and in addition, based on entropy-rightmethod, the county-scale RDLS index system was developed. From the developedsystem, we can see that each district and county in northeastern and southeasternChongqing has bigger RDLS, relatively those in the western economic corridor ofChongqing have smaller ones, which means relatively flat terrain.(2) Based on recorded landslide disaster data of38counties in Chongqing fromyear1951to2011, using ArcGIS10.0, through trend analysis and Natural Breaksmethod, this paper studied the frequency distribution trend and the density distributionof landslide in each district and county; then contraposing landslide density, global andlocal spatial autocorrelation analysis were carried out on Geoda095i software to explore the spatial distribution of landslide disasters in each district and county of Chongqing.The result shows that:①landslide disaster has an obvious spatial difference within thestudied area. The intensity difference situation of landslide disaster strength at east-westdirection is more obvious than that at south-north direction. What’s more, landslidedisaster in the eastern occurred more frequently than that in the western, similarly, thenorthern have more landslide disasters than the southern.②Within the studied area, thedistricts and counties that have higher density of landslide disaster concentrated in theThree Gorges Reservoir area, especially in downtown area of Chongqing; Conversely,those have lower ones are concentrated in the southeastern Chongqing and westernChongqing economic corridor.③Global spatial autocorrelation analysis got a GlobalMoran’s I value of0.1334and a reasonable Z value, which shows that the landslidedensity has higher spatial agglomeration in the studied area. According to the localMoran’s value that derives from the local spatial autocorrelation analysis, landslidedistribution density has integration characteristic in65.8%of the districts and countiesin studied area, while the rest has significant difference.(3) Integrating RDLS with landslide disaster density by Geoda095i software,performing their county-scale correlation analysis of coupling index and spatialautocorrelation analysis among districts and counties of Chongqing, we can drawconclusions as below:①It has certain relevance between RDLS and landslide disasterdensity in each district and county of Chongqing;②The Global Moran’s I value ofcoupling index between RDLS and landslide disasters density in Chongqing is0.3591,matching the inspection of significant level α=0.05, which shows a significantagglomeration feature of their spatial distribution in each district and county ofChongqing;③According to the Local Moran’s I value of Local spatial autocorrelationanalysis,79%of the districts and counties have integrated coupling degree distributionbetween RDLS and landslide disaster, while the rest have significant difference, andfurther verification is performed.