Scale dependence and the temporal persistence of spatial patterns of soil water storage

The concept of time stability as defined by Vachaud et al. (1985) is expanded to include general linear transformations in time and to account for the occurrence of spatial scale dependency. Time stability is described as the temporal persistence of a spatial pattern and is evaluated using correlation analysis of successive measurement dates. Spatial coherency analysis is suggested as a method for examining the temporal persistence of a spatial pattern as a function of spatial scale. Spatial coherency analysis was used to examine the temporal persistence of soil water storage (0–1.7 m) measured every 10 m in a 720‐m‐long transect for drying and recharge events. Soil water recharge altered the spatial pattern of water storage at small scales which was significantly related to surface (topographic) curvature. Drying did not alter the spatial pattern of soil water storage. The study supports the concept that soil water storage at a point is the product of hydrologic processes operating at different spatial scales. The analysis can be used to relate the spatial scale of processes to independent factors.