Spatial and Temporal Soil Moisture Behavior in a Headwater Watershed of the Mantiqueira Range, Minas Gerais, Brazil.

The characterization of temporal and spatial variability of soil moisture is highly relevant in watersheds for understanding the many hydrological and erosion processes, to better model the processes and to apply them to conservation planning. The goal of this study was to map soil moisture of the surface soil layer (0-20cm), in a headwater watershed located in Mantiqueira Mountain region, southern Minas Gerais State, Brazil. The experiment was carried out from may/07 to may/08, analyzing the behavior of soil moisture to different land-use situations (Atlantic Forest, grassland and wetland), using a portable TDR. The mapping was conducted by applying the geo-statistical interpolator (kriging), using the best semi-variogram model adjusted to the experimental semi-variograms, after a previous evaluation of an exploratory data set. The readings were grouped according to the season, and used to generate maps for each. In addition, a simulation kriging (block kriging) was applied to study (over the period) the behavior of soil moisture for each land-use in the watershed. At the beginning of spring, especially in first half of October, the greatest water deficit was observed, with the soil moisture around 21% (volume base). The season with the greatest soil moisture at watershed was the last ten days of December, with values greater than 40%. Also, an important influence of Atlantic Forest was observed on maintenance of soil moisture, reducing the variation in soil water storage and producing a more efficient system of soil moisture conservation in this ecosystem.