Research On Vegetation Cover And Soil Moisture Inversion In Ordos Basin

Ordos Basin is located in the arid and semi-arid region. In recent years, along with the large scale exploitation of mineral resources and groundwater, causing a series of ecological and environmental problems, including rivers dry up, shrinkage of wetlands, land desertification. Therefore, it is of great significance and value that studies the change of vegetation and soil water in Ordos basin.Based on MODIS-NDVI, DEM, and meteorological date, using Arc GIS software and several mathematical statistics methods, the thesis analyzes the spatial and temporal variation of vegetation and the factors affecting vegetation cover. The periodic pattern of NDVI is studied by wavelet analysis method. Based on the MODIS-NDVI、MODIS-LST date, Arc GIS raster calculator is used to calculate the TVDI value in Ordos basin. The thesis analyzes the variation of TVDI with temperature and rainfall and the correlation of TVDI-NDVI and TVDI-Ts. Based on the correlation between GLDAS and TVDI, the thesis inversion the soil water content in the study area.The result shows that vegetation coverage shows a strong seasonal feature within a year and 3~4 years. The vegetation coverage increases slightly from the past 12 years in general while there are obvious differences in the spatial distribution. The NDVI was positively correlated with temperature and rainfall in autumn, while NDVI was a negative correlation with temperature in spring and summer. The change of vegetation in the study area shows the vertical nature and slope nature. The calculation results show that soil moisture in Ordos basin is between 15 mm and 27 mm. The degree of drought is higher in April. With the gradually increased rainfall, the degree of drought eased in May and June. In July and August, rainfall and temperature reach their peak, so the degree of drought is in a moderate level. In September, rainfall decreases significantly and temperature is still high, so the degree of drought increases. The results also show that TVDI significantly correlated with Ts, while a weak correlation with NDVI. When temperature rises, TVDI value increases at first, then turns to decrease. TVDI value decreases with increasing rainfall.The research results have some reference value for understanding the evolution law of vegetation ecological environment in the arid area.