Mean soil water content estimation using measurements from time stable locations of adjacent or distant areas

• Mean soil water content estimation with a time stable point of other areas is feasible.
• This method can ignore the impact of variability in soil properties.
• More accurate estimation can be available for larger areas and deeper soils.
• This method was validated by predicting mean soil water content of larger watershed.

SummaryQuick and accurate estimates of spatial mean volumetric soil water content (θ) are essential for validating remotely-sensed soil water content and water budget analyses. The objective of this study was to test and validate a methodology that utilizes measured θ from the Most Time Stable Locations (MTSLs) to estimate mean θ in an adjacent or distant area while negating the impact of variability in soil, vegetation and topographic properties. Soil water content measured by a neutron probe at depths of 0.1, 0.2, 0.4, 0.6 and 0.8 m in Laoyemanqu watershed on the Chinese Loess Plateau was used to test our methodology. This method predicts mean θ of one area with measured θ at the MTSL from another area. Estimation errors depend on size of the study areas, number of measurement times in the target area and soil depth. A more accurate estimation of mean θ was found when using larger areas and deeper soils. Our method was also validated by predicting mean θ of a larger watershed (Liudaogou watershed) using the θ measurement at the MTSL at Laoyemanqu watershed. The proposed method has great potential for soil water upscaling with socio-economic, environmental and geo-political values.