Spatiotemporal variability of land surface moisture based on vegetation and temperature characteristics in Northern Shaanxi Loess Plateau, China

Vegetation coverage and surface temperature are important parameters in describing the characteristics of land cover, which in combination can provide information on vegetation and soil moisture conditions at the surface. This paper aims to estimate spatial and temporal patterns of soil moisture in the Loess Plateau, China. Using Terra/MODIS images for each 10-day period in 2004 covering the semi-arid North Shaanxi Loess Plateau, a simplified land surface dryness index (Temperature–Vegetation Dryness Index, TVDI) developed by Sandholt [Sandholt, I., Rasmussena, K, Andersenb, J., 2002. A simple interpretation of the surface temperature/vegetation index space for assessment of surface moisture status. Remote Sensing of Environment 79, 213–224.] was used to determine the relationship between surface temperature and vegetation index. From the analysis, it can be inferred that the trend in seasonal change of TVDI is high values in the dry season (spring or summer) and low values in the rainy season (autumn or winter). Moreover, the land surface moisture of each watershed had its seasonal characteristics. The relationship between TVDI and land cover types indicated that water-retention in forest and shrub areas was better than cropland and rangeland in relatively wet conditions, and rangeland was better than forest and shrub areas in dry conditions.