Spatial-Temporal Dynamic Changes of Vegetation Cover in Hexi of Gansu Province Based on MODIS data

Using the MOD13A3 data from 2000 to 2013, Analyze the change of time and space by using the methods of maximum synthesis, trend line analysis, and Hurst index; at the same time, calculate and analyze the vegetation coverage in Hexi area with dimidiate pixel model. The result shows an obvious and overall increasing trend of the vegetation index in Hexi area, Gansu province from 2000 to 2013; the area with strong sustainable variation is the largest as a percentage of the total Hexi area, which is 18.1%, the area with strong anti-sustainable variation is only 0.2% as a percentage of the total Hexi area; the high and medium vegetation coverage areas in 2013 has increased than that in 2000, the association between the variation of high vegetation coverage area in Hexi and annual precipitation is smaller, and generally, the vegetation coverage area in Hexi, Gansu province has a subtle increasing trend.