Dynamic Change Of Vegetation Index And Remote Sensing Research Of Soil Moisture In The Badain Jaran Desert

The Badain Jaran Desert, which is located in the center of arid and semi-aridclimate region in middle Asian, is China’s second largest, the world’s third largestdesert, and is also one of the strongest dust storms source in northern China. With adistinctive native structure, sparse rainfall and intense evaporation, theeco-environment of the Badain Jaran Desert is fragile and it is difficult to berecovered when damaged. Especially in recent half century, the sand dunes in theBadain Jaran Desert were expanding continuously under the influence of climatechange and human activities. The land desertification is very seriously in the edge ofthe desert. It is valuable to carry out a research on regional vegetation variation,impacts on vegetation, and the protection of eco-environment.Based on vegetation remote sensing data MODIS-NADI from2000to2012,applying software ENVI, ArcGIS, and employ linear regression trend method,correlation analysis method and various mathematical statistics, spatial and temporalvariation of vegetation coverage in the Badain Jaran Desert was studied in this paper.The basic characteristics of climate change of the Badain Jaran Desert are analyzedbased on the observed data of monthly mean precipitation，air temperature, windspeed and relative humidity，recorded by8meteorological stations around the desertduring the period2000－2012．The correlation between vegetation coverage changeand meteorological elements was analyzed to provide some essential theoreticalbasis for the regional ecological environment improvement in the Badain JaranDesert. In addition, conbined with the observation data, the thermal inertia modelwas set up and the soil moisture of2000to2012was estimated. On the basis ofabove researches, the main conclusions can be reached as the followings:(1) The vegetation coverage of the Badain Jaran Desert is very low. The annualaverage NDVI varied in the range of0.077to0.092. The variation trend of annualNDVI was increased during2000-2012in the Badain Jaran Desert, and the increaserate was0.009/10a, which showed the vegetation coverage condition had beenimproved. Based on the distribution of spatial variation of annual NDVI showed that the value in the southeast was higher than the value in the northwest of the BadainJaran Desert.The growing season of vegetation in the desert is from June toSeptember in a year, and August is the most productive time of the vegetation duringits growing period.(2) The vegetation is affected by rainfall, wind speed, relative humidity andtemperature. There is positive correlation between vegetation and rainfall and R2is0.5847. There is no obvious correlation between vegetation and air temperature,vegetation and wind speed, and R2are0.2754and0.0107, respectively. Theinfluence of mean precipitation is greater than annual temperature.(3) Based on sub-pixel decomposition model, annual national vegetationcoverage in2000-2012are estimated using MODIS-NDVI vegetation indices. Theresults showed the situation of vegetation coverage in recent years.(4)Combined MODIS image data with the observation data, the thermal inertiamodel was set up and the soil moisture of2013was estimated.