The Research On The Dynamic Change Of Desertification Land Of Nearly Ten Years In The Beijing And Tianjin Sandstorm Source Control

In this study, multiple data including time series of ecological remote sensing products, weather, geographical environment and other relevant geological data were used to study on the land desertification status, dynamics between 2000 and 2010, and the driving factors of the change in Beijing and Tianjin sandstorm source preserving area. This dynamics analysis was be further used to evaluate the effects of the Beijing and Tianjin sandstorm source treatment project. First of all, based on the historical desertification data, and vegetation division, land use, climate, wind erosion, and NDVI data, the desertification status of 2010 was evaluated, including the total area of desertification land, desertification grade distributions. Second, according to NDVI data from 2000 to 2010, the land desertification scope in different years was extracted, which was used to analyze the total area and spatial changes during the 11 years.. Finally, using grey correlation degree and correlation analysis method, the driving force of the regional land desertification change was analyzed from the aspects of natural conditions change and human activities.The results showed that:(1)The study accesses the distribution of the annual average NDVI of the Beijing and Tianjin sandstorm source was between 0.2 to 0.45.(2) Considering wind erosion,land use types and climate data, the NDVI threshold value method was the ideal method for land desertification. The threshold value of 0.3 is good to classify the desertification and non-desertification, with the accuracy of 81%.Instead of using historical data the self-agreement is only 68%.(3) In 2010, the total desertification area of the Beijing and Tianjin sandstorm source area is 22.10×104 km2, accounting for 22.1% of the total area of the study area. Among them, area in severe grade and above took 56.46%, mainly distributed around the Otindag Sandy Land(4)The desertification showed a trend of increasing first, and then decreased between 2000 and 2010. The total desertification area increased by 1.65×104 km2 during the 11 yrs ub Beijing and Tianjin sandstorm source area, but the severe desertification area decreased by 0.17 ×104 km2.(5) In the eastern Inner Mongolia including Chifeng city and the eastern regions of Xilinhot,. the land desertification degree is deteriorated obviously. But in the central of cylinder’s, the northern of Shanxi Datong city, Shuozhou city and Zhangjiakou, the desertification situation improved.(6) The GDP, temperature and precipitation has the influence on land desertification. There was significant negative correlation between rainfall and desertification area, but positive correlation between GDP, temperature and the desertification area. Among them, GDP had the highest correlation degree to the land desertification area and the largest contribution indicating the important influence of human activities on the land desertification. In land use types, the grass is the main source of sand.