Temporal Stability of Soil Water Contents As Affected by Weather Patterns and Soil Properties: A Simulation Study.

Temporal stability of soil water content (TS SWC) is a natural phenomenon that recently attracts attention and finds multiple applications.   Large variations in the interannual and interseasonal TS SWC have been encountered among locations studied by various authors. The objective of this work was to test the hypothesis that the degradation of TS and the perpetuation of representative locations can be affected by the local climate and corresponding weather patterns in consecutive months or years. We selected four climates found in U. S. regions, and simulated the multiyear soil water dynamics for sandy loam and loam soils having a lognormal spatial distribution of the saturated hydraulic conductivity. The CLIMGEN code was used to generate climate-specific weather patterns, and HYDRUS6 code was used to simulate soil water dynamics in independent soil columns. Four different methods were applied to select the representative location. Very low probabilities were encountered of the variation of mean relative differences (MRD) among the columns being independent on climate type. The probability that the variance in MRD depended on sampling frequency was always higher than 70% in the sandy loam soil and was above 97 % in the loamy soil. The interannual variation in MRD from short intensive campaigns was highly probable for all climates. There were more concurrences in the best location selections with different criteria in the sandy loam soil than in the loamy soil for all climates.  The temporal stability appears to be the result of the interplay between weather patterns, soil properties, and samplings frequency. One implication of this factor interaction effect on TS is that a simulation study can be useful to decide on the feasibility of including a search for the representative location based on TS for a specific site.