黄土高原雨养区坡面土壤蓄水量时间稳定性

分析区域土壤蓄水量（SWS）时间稳定性为准确预测土壤墒情提供了理论保障，同时为植被恢复和重建工作提供帮助。利用中子仪获得黄土高原雨养区六道沟流域坡面2005年10月至2006年9月间剖面SWS，通过时间稳定性分析，研究该区域SWS的时间稳定性特征。结果表明：不同月份SWS均表现为中等变异，干旱条件下的变异系数比湿润条件下小。0～4 m的SWS累积概率比其他土层的变化小，平均相对偏差的变化范围（-39%～53%）及标准差（5.6%）较小，spearman秩相关系数均达到0.8以上且呈现出极显著相关，通过时间稳定性分析可以初步确定研究区平均SWS的代表性测点。SWS变化较大时，spearman秩相关系数较小，而SWS变化较小时，spearman秩相关系数较大。spearman秩相关系数为分析该区域SWS的时间稳定性提供了便捷途径。

Temporal stability of soil water storage on slope in rain-fed region of Loess Plateau

The analysis of temporal stability of soil water storage (SWS) is a theoretical basis for the accurate prediction of the soil moisture which can provide help for the vegetation restoration and reconstruction. The profile SWS on a slope was obtained by neutron probe from October 2005 to September 2006 in Liudaogou watershed on rain-fed region of Loess Plateau. The temporal stability of the SWS was conducted by classical statistical and temporal stability analysis. The results showed that SWS in the different months had moderate variability. The coefficients of variation of SWS under dry condition were lower than that under wet condition. The cumulative frequency of 0-4 m SWS changed less than that of the other depths. The mean relative differences of the 0-4 m SWS ranged from -39% to 53% with lower standard deviation (5.6%). The 0-4 m SWS had higher spearman rank correlation coefficients up to 0.8 with significant correlation. The results of the temporal stability preliminarily determined the representative sites. The spearman rank correlation coefficients were small when the SWS varied greatly, but increased when the SWS remained more or less stable. The spearman rank correlation coefficients can provide a convenient way to estimate the temporal stability of SWS in the study area.