Dynamic Monitoring Of Desertification In The Tarim Basin Based On RS And GIS Techniques

As the core of the Silk Road economic zone in the core area,the Tarim Basin has rich natural resources,But also the Tarim Basin is extremely fragile natural ecological environment along the Silk Road economic belt.Land desertification is serious in the area.Coupled with the interference of human activities,Especially the irrational use of water and soil resources.Harsh environment seriously restricts the regional ecological security and economic sustainable development.It is important to understand the current desertification process and the dynamic trend of Tarim Basin.In this study,the spatial and temporal variations of land desertification in the Tarim Basin during 2000–2014 were monitored and analyzed using RS and GIS technologies based on the vegetation coverage from Normalized Difference Vegetation Index?NDVI?data of MODIS.Besides,the impacts of climate change and human activities on the desertification for the Tarim Basin were investigated.The results showed that:?1?The Tarim Basin was characterized by the largest proportion of severe desertification?64.63%?,followed by moderate desertification?17.70%?,and slight desertification?9.95%?,and non-desertification was the least?4.18%?.From the standpoint of space,the area of severe desertification is mainly distributed in the central region of the Tarim Basin,including the Taklimakan Desert,and the desertification in the northeastern direction of the Tarim Basin has intensified in the past 15 years;Moderate desertification is mainly distributed in the desert and oasis transition zone,moderate desertification expansion significantly along the Tarim River of mainstream;The mild desertification areas are mainly distributed in shrubs and grasslands,mainly located in the Weigan River-Kuqa River Oasis.The non-desertification area is mainly the artificial oasis of human activities and the edge of oasis.?2?During the past 15 years,the severe desertification area decreased at a rate of 0.0076 km₂·a-1.However,the moderate desertification area increased rapidly,with an average annual rate of 0.0169 km₂·a-1,the slight desertification area had a slightly increasing trend with a rate of 0.0093 km₂·a-1,and the proportion of non-desertification increased significantly with a rate of 0.0289 km₂·a-1.?3?The accuracy of the MODIS data is evaluated,and the accuracy of the assessment is 75.25%,which indicates that the results of the two kinds of resolution data products are basically the same.Through the Tarim Basin center of gravity trajectory migration display,The gravity center of the severe desertification migrated to the northeast part in the past 15 years,with a migration distance of 21.08 km.Indicating that heavy desertification to the northeast of the migration,mainly due to the presence of the Taklimakan desert northward expansion.The non-desertification migration to the southwest is 65.23 km,and the migration direction is related to the water source condition.It is also closely linked with the continuous expansion of the artificial oasis and the expansion of the cultivated land area.At the same time,the regional analysis of desertification aggravated that the edge of the Tarrakuma Desert is located in the desertification area,desertification to oasis expansion.Through the raster calculation,the desertification aggravated area from 2000 to 2014 accounted for 9.04% of the total land area of the Tarim Basin.?4?The changes of desertification were the results of the interaction of climate change and land-use change.Annual precipitation was closely related to desertification with a correlation coefficient of 0.45.The correlation coefficient of annual mean temperature and desertification is-0.24.At the same time,the expansion of cultivated land area,From 23.4×10₃km₂ to 36.58 × 10₃km₂,which has increased by 13.18×10₃ km₂ during the last 15 years,accelerated the desertification processes of the peripheral oasis area.Among them,the area along the Tarim River dry area increased the fastest,indicating that human activities are more intense,while strong squeeze the ecological water,accelerating the oasis of the external desertification process development.