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.