Soil moisture temporal stability analysis for typical hilly and gully re-vegetated catchment in the Loess Plateau, China

In arid and semi-arid regions, soil moisture in particular is a key integrative state variable that is linked to a range of hydrological, ecological, climatic, and geological processes; however, it is usually highly variable in space and time. To overcome this issue, it is necessary to study the temporal stability of soil moisture. Here, we intend to take a soil moisture temporary stability analysis for the typical hilly and gully re-vegetated areas in the Loess Plateau. Using cumulative frequency distribution, the relative difference, and Spearman's rank correlation coefficient to conduct temporal stability analysis for the soil moisture at five slope transects of a typical hilly and gully re-vegetated loess catchment during the rainy season of 2012. We found the soil moisture spatial distribution pattern for the small, typical hilly and gully re-vegetated Loess Plateau catchment to be stable. However, it is not always easy to find sites representative of the catchment average moisture content under different conditions; but it is easier to find sites with extremely high water content in the slopes. A new method for identifying temporally stable locations in typical re-vegetated hilly and gully loess areas is needed. The relationships between soil moisture and other catchment conditions for the diagnosis of representative sites must also be determined. The pattern stability and type stability of soil moisture guarantees that sampling comparisons in this area can be conducted at different times to compare the differences between various land cover types, especially with regard to deep soil depth.