Spatial And Temporal Distribution Pattern Of Soil Moisture About A Typical Small Watershed In The Upstream Of Heihe River

The spatial and temporal distribution of soil moisture is an important part in some soil moisture model and water balance research. We selected a small basin in the upper reach of Heihe river and collected the soil moisture data with TDR in the growing season(from May to September). The research results are as follows:1)seasonal dynamics of soil moisture in growing season can be divided into three stage, that is, accumulation period, stable period, decline period.2)Except the soil moisture of Qinghai Spruce increasing from the surface layer to the deeper layer, others’ are on the contrary, which is because that water consumption is given priority to with vegetable transpiration.3)Slope position isn’t a important factor about the spatial distribution of soil water content,The same vegetation cover make the soil water tend to homogeneity.The spatial heterogeneity is mainly manifested in different vegetation cover,and because of the heterogeneity of seasonal frozen soil,Spatial difference of soil water within different vegetation cover is changing from May to July,from July to September,the spatial pattern of different vegetation is stable: brush>Qinghai spruce forest>Sabina przewalskii forest>Grassland.Therefore when taking a study on soil moisture simulation in Qilian mountain,vegetation cover should sever as an important reference factor,and should take soil temperature into account,which determine the seasonal frozen soil freezing or thawing.4)The profile SWS(0-60cm) on three slopes was obtained by TDR from May 2014 to September 2014 in Tianlaochi watershed of the upstream region of Heihe river. The temporal stability of the SWS was conducted by classical statistics and temporal stability analysis. The results showed that SWS depended strongly on precipitation as expected. Temporal stability was thus higher at the points characterizing drier conditions from the analyzing of mean relative difference.5) The result of temporal stability through three ways(MRD、ITS、MABE) preliminarily determined the representative sites. Across the analyzing of spearman rank correlation coefficients,we can get that majority of the coefficients were significant at p<0.01, which indicated that SWS of three slopes all have strong time stability.6)The spearman rank correlation coefficient can provide a convenient way to estimate the temporal stability of SWS in the study area.