Landscape Ecological Risk Assessment And Landscape Pattern Optimization In Yanqing Sandstorm Region

With the progress of the society,more and more attention is paid to sandstorm and the resulting ecological problems in the whole world.Beijing also suffers from the natural disaster.In recent years, sandstorm diffusion happened frequently and has caused serious problems.In order to improve the environmental quality and protect the ecological safety,governments have taken some measures,But from the overall analysis,we can see that Beijing's ecological environment is more frangible,and ecological quality is more lower.Corresponding,the task of preventing and controlling desertification is severely difficult and important.A case study was carried out in Yanqing Sandstorm District,which is located in the northwest suburb of Beijing.In this artical,based on 3S techniques,we took 30-m resolution Landsat Thematic Mapper(TM) images(in 1989,in 1996,in2005) of the Beijing region and the climate data from 1962 to 2005 as the date foundation,and used integrated approaches of field investigation,landscape ecology theory,principle of landscape ecological risk and natural disaster theory.We objectively analyzed and assessed the risk of landscape structure and wind erosion in research region,and simulate the sandstorm diffusion.Based on that,according to methods of landscape ecology and ecological risk theory,this study discusses the landscape optimization pattern theoretically and technically for controlling desertification and reducing sandstorm diffusion disaster in the research areas.This paper includes the following several parts:Firstly,base on the conditions in Yanqing,we through collect and deal with many correlative data to build fundamental geographic database in GIS environment;secondly,According to risk theory of Landscape Ecology and natural disasters theory,we used landscape structure index to Construct Landscape ecological risk index.By risk cell division,we calculated the risk index.At last,through kriging prediction,we get the map of Landscape ecological risk.The results indicate:As a whole,in the research distract,in 2005,the ecological risk decreased obviously more than what in 1996,but but high ecological risk distract still exist.Thirdly,according to risk theory of Natural Disasters,we analyze the disaster-pregnant environment and natural disaster-causing factors of study field,and select four indicators(land use,vegetation cover,TDVI and soil type) to assess the sandstorm hazard of underlying surfaces in the research field.According to the study the five classes of blown sand disaster degree were defined,the results indicate that from very low risk level to very high risk level,and the proportion of corresponding land areas are 7.57%,29.38%,14.28%,26.23%和22.54%respectively;on the base of sandstorm disaster hazard assessment based on GIS environment,by combining with the wind forces factors create the spatial pattern of sandstorm diffusion risk.It synthetically explains the spatial distribution character of the risk level;fourthly,in a landscape the movements of flow,energy and material are common related to some factors such as distance,time,impedance,etc.according to the principle we built the accumulative cost distance model,and combines with above sandstorm,diffusion risk assessment achievement,we simulate the sandstorm diffusion use GIS technology;at last,based on the landscape function theory,combines with landscape ecological risk assessment achievement and sandstorm.Diffusion risk assessment achievement to analyzes the spatial difference of the ecological function in Yanqing and through accumulative cost distance model to built the ecological corridors and ecological nodes for the landscape pattern optimization in wind-eroded regions.Now,at home and abroad there are many researches on sandstorm mechanism of blown-sand activities and the hazard assessment,while from the viewpoint of risk the sandstorm diffusion research combined the results of landscape structure ecological risk assessment and risk assessment sandstorm diffusion with ecological spatial character of landscape are quite rare for combating and controlling desertification.The article 's aim is to explore and study in this field.This paper tries to revise the common theory for sandstorm diffusion and natural disaster prevention guided by the landscape ecology and ecological risk theory,based on accumulative cost distance model and 3S techniques.