Study On Temporal And Spatial Variation Of Soil Moisture In Loess Area Of West Shanxi Province

Through measuring the soil physical and chemical character, the long-term soil moisture in the forest land of artificial vegetation in research area, and by using statistic method, geological statistics method and GIS, etc., theis paper focus on the validity soil moisture, the temporal and spatial dynamic variance law of soil moisture of different vegetation, the temporal and spatial heterogeneity of soil moisture at different scale and the relation between soil moisture of slope and terrain factor and other content related to the items mentioned above.The study on the heterogeneity of soil moisture found that the soil moisture in the research area has a kind of medium correlation with time and space of different scale. The samples scale is different; the characters of soil moisture on time and space heterogeneity are different correspondingly. From the point of space, the nugget, the sill value and the variable- range of the vary function of grid 20m×20m are larger than that kind of grid 2m×2m. As a whole, the extent of space heterogeneity of soil moisture in scale of 20m×20m is further larger than that kind of 2m×2m. From the point of time, the extent of time heterogeneity of 15 days is further lager than that of 1 day; at 1 day scale, the micro variety of soil moisture on time can be shown basically. In 15 days scale, the variable- range of soil moisture is 133.5 days, while at 1 day scale, it is 5.6 days. As the sampling time is different, the space heterogeneity of soil moisture is different: in August, the nugget, the height, the sill value and ratio of structure are smaller compared with in April; it shows that the space heterogeneity of the soil moisture is lower in August.Based on the time and space vary function model of soil moisture, Kriging interpolating method is used to protract the figures of the spatial distribution and the time pattern of soil moisture. It can be seen that the special sampling scale of 2m×2m can reflect the condition of soil moisture more detail ; compare with the scale of 1 day, in the scale of 15 days,the vary range of soil moisture is larger and the vary extent is more complicated.By overlaying the figures of the spatial distribution of soil moisture with the figures of terrain factors to get an attribute database about the relation between soil moisture and terrain factors, and analyze the main terrain factors affected soil moisture, the result shows that: between the soil depth of 0 and 30 cm, the slope direction is the predominant factor, the elevation is secondary, the slope degree is last; while between the soil depth of 30 and 60cm, slope degree is predominant, the impact of slope direction on soil moisture is minimum. The result of cluster analysis shows that the slope direction can be classified into two types: clockwise 292.5°~112.5°(south-slope), 112.5°~292.5°(north-slope), it is coincident...