Layered characteristics and driving mechanisms of temporal soil moisture variation in a small watershed of the southern Loess Plateau

Wangdonggou watershed located in the southern Loess Plateau was selected as the study area in this paper.Layered characteristics and driving mechanisms of seasonal and interannual soil moisture variations in the small watershed were comprehensively studied through a long-term observation of soil moisture in 600 cm soil profiles of typical plots.Soilwatercontentin the 0~50 cmlayerchanged intensivelywith season.Soilwatercontentin the 0~150 cmsoil layer decreased to the lowestbefore rainy season.In contrast to drought season,the depth of soil water recharged in Decemberwas as much as 460 cm for wheat land,while the maximum depths recharged were about 260 cm forRobinia pseudoacaciaforestland,apple orchard and alfalfa field.Temporal variations of soil moisture in the profileswere characterized by a layered distribution and were closely related with landuse type.As for the same measuring point,soil water contents in the 300~600 cm layerofRobinia pseudoacaciaforestland and apple orchard in 2011 were lowerthan those in2003,while soil water contents in the same layer of wheat land and natural grassland in 2011 were higher than those in2003.Both landuse type and topography are the main driving factors for soil moisture change and however,landuse type has more significant effect on soil moisture in deep layer.