Risk Assessment Of Sandstorm Diffusion And Landscape Pattern Optimization In Beijing Region

Sandstorm diffusion is one of the most serious ecological problems and is paid widely attention in the whole world. Beijing region is one of most serious regions which are subjected to the sandstorm disaster deeply. In recent years, sandstorm diffusion takes place extremely and frequently in Beijing regiong. They pose a serious threat to the ecological security, and bring a negative influence upon Beijing's reputation in the world. So controlling desertification and reducing sandstorm disaster become a primary task for landscape ecological planning and constructing in Beijing region.Currently, there are lots of researches on sandstorm hazard assessment and the mechanism of blown-sand activities at home and abroad, while from the viewpoint of risk the sandstorm diffusion researchs combined with ecological spatial character of landscape are quite rare for combating and controlling desertification. The aim of the article is to explore and innovate in this field.A case study was carried out in Daxing District, which is located in the southern suburb of Beijing. In this thesis, based on 3S techniques, took 30-m resolution Landsat Thematic Mapper (TM) images (in 1996, in 2001, in2005) of the Beijing region and the climate data from 1960 to 2005 as the date foundation, used integrated approaches of field investigation, principle of wind erosion and disaster system theory, we analysis and assess the risk of wind erosion in Daxing country objectively. On the base of that, according to methods of landscape ecology, this study discusses the landscape pattern optimization pattern theoretically and technically for controlling desertification and reducing sandstorm disaster in the future. This paper includes several parts as follow: first of all, on the base of the conditions in Daxing, we deal with correlative date and build fundamental geographic database in GIS environment; secondly, according to risk theory of Natural Disasters, though analyzing disaster-pregnant environment and natural disaster-causing factors of study area, four indicators (land use, vegetation cover, organicmatter and soil type) are selected to assess the sandstorm hazard of underlying surfaces in the field, the five classes of blown sand disaster degree was defined, the results indicate: from very low risk level to very high risk level, and the proportion of corresponding land areas are 14.8%, 22.4%, 28.6, 19% and 13.2% respectively; thirdly, on the base of sandstorm disaster hazard assessment, based on GIS, the spatial pattern of sandstorm diffusion risk is created by combining the wind forces factors, it is can synthetically explain the spatial distribution character of the risk level; fourthly, according to the principle that the movements of flow, energy and material in a landscape are related to some factors such as distance, time, impedance, etc, the accumulative cost distance model is built, and combines with above risk assessment achievement, the case on sandstorm diffusion is simulated in GIS; fifthly, based on the landscape function, this study analyzes the spatial difference of the ecological function in Daxing, searches after the methods of landscape pattern optimization in wind-eroded regions.The sandstorm diffusion is an ecological environment problem which is difficult to analyze. In this study, we find a new and better method to assess risk of sandstorm diffusion than traditional simple methods. Based on 3S techniques, integrated approaches of principle of wind erosion, risk theory and landscape ecology, this study puts forward the overall scheme of landscape pattern optimization in Daxing country. The methods and final results from this study are expected to be useful for landscape ecological planning, controlling desertification and reducing sandstorm disaster in Beijing region.