Abstract: Based on the MODIS satellite image data and field survey from 2010 to 2019, we accomplished the remotely-sensed monitoring of soil moisture in the main stream of Tarim River from a macroscopic perspective with the support of geographic information technology. Results revealed that the reflectance of MODIS band 7 was negatively correlated with soil moisture. Soil moisture in the upper, middle and lower reaches of the main stream of Tarim River varied greatly in space and time during the year. By comparing different river reaches in the same time period, we found that the soil moisture in the upper reaches of Tarim River was higher than that in the middle reaches and that in the lower reaches in sequence. Meanwhile, by comparing different time periods of the same reach, we discovered that the increment of soil moisture in the upper reaches was larger than that in the middle reaches and lower reaches in sequence. Moisture of soil (0-10 cm) in the main stream of Tarim River varied markedly among seasons. In 2019, the maximum soil moisture (6.29%) occurred in June, while the lowest (around 4.16%) in February. In the past decade, each February and lower reaches witnessed the biggest changes in soil moisture data, with the C_V both exceeding 15%.

Key words: soil moisture, dynamic change, remotely sensed monitoring, MODIS, Tarim River basin