中文摘要：

土壤水分受降雨和地下水的共同补给作用，是陆地水循环的重要环节。通过模拟试验，结合土壤水同位素特征，以黄土高原黄绵土为研究对象，研究降雨入渗和地下水补给方式下土壤水分的运移变化特点。结果表明：土壤体积含水量随时间的延长而增大，最终趋于稳定，土壤水分的运移有明显滞后效应；土壤水氢同位素受补给水源、交换}昆合以及蒸发的影响，随时间的延长，补给水源的影响逐渐减弱，水分的交换混合和蒸发作用逐渐显现，土壤水最终达到动态平衡状态；两种补给条件下，土壤水运移方式均为活塞式推进，降雨入渗方式土壤水δD随土层深度的增加先减小后增大最终趋于稳定，表层0～5cm土壤水由于蒸发富集重同位素，5～20cm土壤水滞留时间最长，保水能力最强，地下水补给方式下土壤水δD随土层深度的增加而减小，上层土壤水δD由于蒸发富集重同位素，下层受地下水补给影响贫化；两种补给方式下土壤水δD与δ^18O有良好线性关系，降雨入渗方式土壤水蒸发分馏作用大于地下水补给方式，地下水补给具有较好的保水效果。

英文摘要：

Soil moisture, affected jointly by rainfall and groundwater, plays an important role in terrestrial water recycling. Hydrogen and oxygen isotopes can be used as tracers to study water movement and migration in the soil. Stable isotope compositions of soil water can be used to reveal information about a number of hydrological processes in soil, including infiltration, evaporation, transpiration and percolation, which is difficult to obtain by other techniques. The Loess Plateau in northern Shaanxi with loessal soil as its dominant type of soil, is arid in climate and scarce in water resource. Anumber of studies documenting tracer movement in the soil column except for using loessal soil to study soil water movement under differential recharge based on hydrogen and oxygen isotopes. Researches on soil water movement and migration in loessal soil may help understand characteristics of soil water movement, guide local agricultural production and improve water utilization efficiency in the Loess Plateau. A simulation experiment using soil columns was carried out in the State Key Laboratory of Northwest Arid Area Experimental Ecology and Hydraulic Engineering, Xi＇an University of Technology. With the aid of isotope technology, exploration was done of temporal variation of soil water movement in loessal soil, temporal variation of distribution of isotope in soil water in the soil profile and relationship between oxygen and hydrogen isotopes in the soil water as affected by rainfall or groundwater, in an attempt to elaborate characteristcs of soil water movement in loessal soil relative to source of the recharge. During the experiment distributions of soil water content and hydrogen isotope in the soil profile were monitored 1, 3, 5, 10, 15, 20 and 30 days after the end of the recharge and relationship between oxygen and hydrogen isotopes in the soil water was fitted with a linear model. Results show that （ 1 ） being recharged with water from either source, rainfall or groundwater, the soil water increa