The response of infiltration depth, evaporation, and soil water replenishment to rainfall in mobile dunes in the Horqin Sandy Land, Northern China

To understand the relationships among rainfall-infiltration-evaporation-replenishment in mobile dunes in the semi-arid areas of China, we used the Container of Water Distribution (100 x 100 x 120 cm(3)) to examine rainfall infiltration, soil water redistribution, and soil surface evaporation under natural and simulated rainfall conditions. The results showed that infiltration depth was linearly related to rainfall amount and intensity. Rainfall amounts larger than 13.4 mm, could replenish soil water at 60 cm depth after redistribution, while with rainfalls larger than 39.8 mm, infiltration depth could exceed 120 cm. Rainfall amounts larger than 50 mm produced saturated soil water at 120 cm depth, and replenishment amount accounted for 40.4 % of the total amount of rainfall. Soil surface evaporation exhibited a relatively minor change with increases in rainfall when rainfall was larger than 11.8 mm. The amount of evaporation and soil water content were significantly correlated at 0-60 cm soil depth, but not below. These results suggest that the maximum effective depth of evaporation is 60 cm below the ground surface, and that rainfall of 13.4 mm is a threshold distinguishing effective from ineffective rainfall in the mobile dunes of the Horqin Sandy Land.