Spatial distribution dynamics of topsoil moisture in shrub microenvironment after rain events in arid and semi-arid areas by means of high-resolution maps

Understanding the dynamic patch mosaic of topsoil moisture on arid hillsides has implications for understanding eco-geomorphic processes. The present study used high-resolution maps to investigate the spatial distribution of moisture in the topsoil on the shrub microenvironment scale, and its dynamics during the first days after rain events. These maps were acquired by a thermal infrared (TIR) method, based on close-range TIR imaging and on a model in which spatially consecutive TIR data are converted into soil moisture values. The main results show that, in addition to the general diminishing trend of topsoil moisture content, and in spite of the specific differences between the two research sites, there was, in both arid and semi-arid zones, a general spatio-temporal pattern of topsoil moisture in a shrub microenvironment during the first days after rainfall. This pattern is manifested in the presence of a changing moist patch under the shrub, and diminishing moisture content gradients, from the shrub center towards the bare soil that vary over space and time. An improved understanding of surface water resources is gained from investigations of the spatio-temporal patterns of soil moisture during and following rainfall events.