Estimation of soil surface moisture in arid and semi arid rangelands using remotely sensed Temperature/Vegetation Index measurements (TVX) (Case Study: Khorasan Province)

Soil surface moisture and it's spatial and temporal variability is one of the most importantenvironmental variables. Due to the difficult, costly and time consuming measurements of field studies, this parameter has not been used widely in climate models. Nowadays, with the increasing development of science, adoption of new technologies for proper management of limited water and soil resources is necessary. The objective of this research was to analyze the application of MODIS images for estimating the soil surface moisture in arid and semiarid rangelands with ephemeral vegetation cover using TVX. Field data measurments of soil surface moisture and some daily meteorological parameters in three station of Mashhad, Golmakan and Neyshaboor of Khorasan province were used for more accurate estimate of soil surface moisture from 2003 to 2005. NDVI, Brightness Temperature of the bands (BT31, BT32) and Land Surface Temperature (LST) were derived from MODIS images and TVX slope was calculated. Different regression models were fitted to assess the relationship between TVX slope and soil surface moisture. According to the results, soil surface moisture in arid and semiarid climate showed a good correlation with TVX slope.