Study on Temporal and Spatial Heterogeneity of Soil Moisture Using Geological Statistics Method on Loess Plateau

Taking typical slope in the Caijiachuan watershed as an example on Loess Plateau of China,the analysis of the spatial distribution of soil moisture was focused on using Kriging interpolating method and then the temporal and spatial heterogeneity of soil moisture was studied.In research area,313 soil moisture sites were arranged on slope at same scale(20 m×20 m) and then soil moisture was detected by TRIME-TDR(two seasons: dry and rain;two layers:0～30 cm and 30～60 cm).The results show that: the 0～30 cm soil moisture is lower than 30～60 cm and it has a high variation coefficient in April.In August,the 0～30 cm soil moisture is higher than the 30～60 cm soil depth and also has a greater variation coefficient;the surface layer and bottom layer has a same soil moisture but in August the spatial heterogeneity has no obviously change than April;The average soil moisture in different depth of soil profile is about 10%～15% in April.While the surface layer soil moisture is 10%～15% but bottom layer lower than 10%.It is shown that the soil moisture is enough to provide the plant growth in initial stage.but it cost more water when the plant growth best.