Temporal stability of soil water storage analysis by the improved mean relative difference in two deposited-soil farmlands

Temporal stability of soil water storage (TSSWS) is of considerable interest in estimating the mean soil water storage (SWS) across the study area for validating the remote sensing products and reducing the observation efforts. However, the general mean relative difference index usually balances the positive and negative relative difference values. Thus, it may find the weakly representative site for mean SWS estimation. Revised mean relative difference, i.e., the absolute value of general relative difference, was used in two deposited soil farmlands (DFs) to analyze the TSSWS. The soil water contents were measured at 18 sites of each DF in 1.5 years. The results showed that revised mean relative difference index was more accurate than normal one in finding the best location to represent mean SWS in the DFs. This can be applicable to sites where SWS is not consistently higher or less than the average value. The SWS in the location which was near to the middle DF showed the strongest temporal stability and behaved the best location to estimate the mean SWS. Revised mean relative difference may be a better criterion for the application of temporal stability tool in soil water field observation.