Space-timemporal Simulation Of Land Desertification In Three Rivers Sources’s Area

Shiqu County is located in eastern Tibetan Plateau. Jinsha River, YalongRiver and Zhaqu that is the first level branche of Yellow River run through this area, soit is a typical Three Rivers sources’s area. It is the global warming, glacial retreat,human’s damage to grassland, unscientific pasturing and a serious rodent and pest thatled to over grazing and an extremely bad destruction to the grassland. Landdesertification in Shiqu County is becoming worse and worse. Shiqu County’s mainlydesertification is land sandification. In order to make a better knowledge of the landsandification situations and take effective preventive measures, the local governmenthave made artificial investigations in land sandification since the year of1999, but thiswas not only a time and labor wasting investigation method but also had a limitedmonitoring range. To rapidly extract the land sandification information by usingmoderate resolution remote sensing images and take a precise spatial and temporalsimulation can help to effectively analyze the scope and degree of land sandification.And thus to take effective managements for spatial and temporal simulation can providedecision support to the prevention and control of land sandification.This thesis focuses on rapid extraction of the information about land desertification.It combines vector machine method and desicion tree analysis by using the image dataprovided by Landsat5, and the accuracy can get up to87%. Compared with the land usedata changes in1994,2006, and2009, the culitivated area of Shiqu county reducedsharply and construction land increased gradually. At the same time, land sandificationarea is increased significantly, which has much to do with the unreasonable andunscientific grazing. Meanwhile, in recent years, under the influences of nationalmacro-policy and in order to realize the goal of developing by leaps and bounds,construction land expanded rapidly, which not only have taken up a lot of agriculturalland but also did damage to the surrounding plants and ecological environment. Through field investigation, a lot about Shiqu county land sandification waslearned from the local land and resources bureau, environmental protection bureau andother related department head. Combined with literature, by analyzing and summarizingShiqu county land desertification influence factor, constructing a cellular automatonmodel based on analytic hierarchy process(ahp), the spatiotemporal structure of Shiqucounty land sandification situation was simulated.In cellular automata model of the design process, through experiments: thetraditional way of1,0value calculation method of the field effect is ineffective used instimulating the non-decertified area of land sandification This paper, abandoning thetraditional neighborhood effect calculation methods of sandification andnon-sandification, according to the influence degree of land desertification phenomenoncaused by different land use types in the surrounding area, gives neighborhood differentneighborhood effect degrees according to the different land use types. Results show thatthe neighborhood affect calculation method, simulates the land sandification resultaccords more consistent with the actual situation and simulation accuracy is higher.The realization of the cellular automata model uses the IDL language. By usingobject oriented method, abstract the cellular automata model classes. some key methodsof cellular model classes, including: transformation probability value calculation,neighborhood effect calculation, uncertain factors and restriction factor etc.Object-oriented methods make a cellular automata model design more concise, easier tomaintain and better in model extension performance. In order to make the cellularautomata model has good reusability, this paper designed a dynamic impact factor tableswhich can realize the dynamic management of impact factor data. Model also providesseveral neighborhood structure choices, which makes the model more universal.According to the design of cellular automata model algorithm, this paper simulates theShiqu county land sandification of space-time, the accuracy of which can reach80.19%.Finally in this paper, the Qhiqu county land sandification is graded, and accordingto the characteristics of different liability division, the author put forward thecorresponding prevention and control advices...