Spatio-Temporal Evolution of Soil Moisture in the Headwater Area of the Yellow River

It is of great significance to study the spatio-temporal evolution of Soil Moisture (SM) for soil water resources and coping with climate change. The fusion product data set between 1978 and 2020 was obtained based on the European Space Agency Climate Change Initiative Soil Moisture (ESA CCI SM) in the Headwater Area of the Yellow River in China. The trend and spatial characteristics of SM in the Headwater Area of the Yellow River during the study period were analyzed by using statistical analysis and B-G diagnostic algorithm, the satellite remote sensing data were verified by using SM observation station data in MAQU. Some conclusions could be drawn: (1) The correlation is significant (R=0.8) between the ground observation data and ESA CCI SM, and the error of the average value of the two was 0.01. ESA CCI SM deviates so little from the measured data that it can be used to characterize variation characteristics of SM in the study area; (2) The SM showed a decreasing trend over the years in the Headwater Area of the Yellow River, the SM content fluctuated greatly for several years but didn't occur abruptly. The change of SM was most obvious during 2002-2007; (3) The spatial pattern was east west high low and meteorological north low. The seasonal difference was obvious, there was an "M" shaped change trend during the year and the double peaks appeared in May and September. The spatio-temporal distribution of SM was revealed to provide important parameters for water and energy exchange between land and atmosphere.