关键词: 沙地水分, 降雨入渗, 土水势, 含水率, 吸力

Abstract: Shapotou Desert Experimental Research Station is situated in the southeastern fringe of Tengger Desert,with an annual rainfall of 186.2 mm. Neutron probe, tensiometer and automatic rain gauge have been installed in bare sandy land to measure soil moisture, soil water potential , rainfall amount and its intensity. Based on the observed data, the processes rain water of infiltration and redistribution were analyzed.The results are as followings:(1)Volume water content and suction power reflected the characteristics of quantity and energy of soil moisture respectively. The observed data showed that the change process of soil moisture content was consistent with the energy transmitting process,and the moisture sorption process was faster than the desorption one in sandy land.Volume water content and suction power varied from high to low from top to bottom during the rainwater infiltration process. From the observations one might conclude that 0.6 m depth was a dividing line indicating the brisk extent of soil moisture.(2)Vertical transimission speed of soil moisture under rainfall condition varied from 0.35 to 2.29 cm/h. The initial infiltration speed of rainwater was low due to the existence of the dry sand layer at the surface.However, as a whole , the soil water transmitted fastly at first , then slowed down and finally tended to be stable.(3)The boundary condition of rainwater infiltration was controlled by water supply, The infiltration rate was equal to rain in tensity, and cumulative infiltration was equal to rainfall. Observations of soil water pontential showed that zero flux plane was above 0.2 m depth, and soil moisture moved down constantly below 0.2 m depth in the rainy season. The redistribution of rain water played a key role in the dynamic variation process of soil moisture.

Key words: Soil moisture, Rainfall infiltration, sandy land