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【目的】探明不同地下水位深度条件下,地表径流过程中溶质的迁移规律。【方法】采用模拟试验,研究3种地下水位(地下水位与地表持平、低于地表5和10cm)及不同地表径流流速下(90,120,200,250mL/s),土壤溶质迁移到地表径流过程中,其在3种途径(土壤侵蚀、伯努利效应、扩散)下的变化规律。【结果】当地表径流流速小于200mL/s时,随着地表径流流速的增加,土壤溶质流失加剧,伯努利效应和扩散作用是引起土壤溶质流失的主导因素;当地表径流流速大于200mL/s时,土壤侵蚀是引起土壤溶质流失的主导因素。径流60min后,当地下水位低于地表5～10cm时,随着土层深度的增加,土壤剖面中溴化物质量浓度则逐渐增大。当地下水位与地表持平时,混合层深度为0.9～4.6mm;当地下水位低于地表5和10cm时,混合层深度均小于2.5mm。【结论】土壤溶质迁移过程与地表径流流速和地下水位高低有重要关系。
【Objective】 The objective of this study is to investigate the solute transport during surface runoff under different water table depths. 【Method】 The simulation experiments were conducted to study the effects of soil solute transport to surface runoff on three kinds of groundwater table (the groundwater level is flat with the earth’s surface, below the surface 5 and 10 cm) and different surface runoff velocities (90, 120, 200 and 250 mL / s) 3 ways (soil erosion, Bernoulli effect, diffusion) under the changing law. 【Result】 When the surface runoff velocity was less than 200 mL / s, the soil loss caused by soil runoff increased with the increase of surface runoff velocity. The Bernoulli effect and the diffusion effect were the dominant factors causing soil solute loss. When the surface runoff velocity was more than 200 mL / s Soil erosion is the dominant factor that causes soil solute loss. After 60min of runoff, when the underground water level is 5 ~ 10cm below the surface, the mass concentration of bromide in the soil profile gradually increases with the increase of soil depth. When the local water table is level with the earth’s surface, the depth of mixed layer is 0.9 ~ 4.6mm; when the local water table is lower than 5 and 10cm above ground surface, the depth of mixed layer is less than 2.5mm. 【Conclusion】 The process of soil solute transport is closely related to the surface runoff velocity and groundwater level.