盐渍土系统土壤水-地下水转化规律研究

Water transportation between soil-groundwater in sodic saline soil system

通过野外定位观测和室内分析,探讨了苏打盐渍土微域特征(32m长的横截面)及其水分和地下水之间的转化规律。结果表明:土壤特征以及微地貌格局是制约土壤表层水分迁移的主要因素,并由此形成了大汽降水-土壤水-地下水转化的特殊模式。盐化草甸土分布在相对低洼的部位,苏打碱土分布在微坡地和高平地。苏打碱土质地为粉砂质亚粘土-粘土-粉砂-砂砾垂直结构,盐化草甸土以粉砂和砂砾结构为主。地表径流为水分迁移的关键环节,盐化草甸土成为地表水和地下水转化的通道。承接微坡地和高平地的径流,盐化草甸土在雨季含水率较多(甚至大到饱和)且迅速补给地下水,使地下水位逐渐上升。坡地土壤(苏打盐渍土)整个土层的含水率变化不显著。运用Vensim对盐渍土系统的土壤水-地下水的转化过程进行了模拟,结果与观测数据基本一致。在现代盐渍化过程研究中,以坡面系统为研究单元并考虑坡面径流,才能认识到盐渍化地区土壤水-地下水之间转化的实质。

By in-situ observation and analysis in laboratory, micro structure （a 32-m-long transect） and water and salinity transportation with shallow groundwater were discussed. Results show that micro relief pattern and soil prosperities are key influence factors for soil water transportation, therefore, resulted to special transform model of groundwater-soil water-atmosphere water. Saline meadow soil distributes in the micro basin, and sodic alkaline soil in micro slope or micro flat. Particle size profile of alkaline soil was silty subslay-slay-silt-gravel structure; the main component in micro basin was silt and gravel. Shallow basin （sodic saline meadow soil） became the channel of surface run-off and shallow groundwater transportation. Accumulated run-off from micro slope and flat, moisture content was pretty large （even reach saturation condition） in micro basin （saline meadow soil） in rainy season and supply shallow groundwater quickly, elevated the depth of shallow groundwater gradually. The variation of soil moisture in micro slope （soidc alkaline soil） was pretty weak. Vensim software was applied to simulate the transform process between groundwater, soil water and atmosphere, the simulation was agreement with observed value. The study based on micro slope system and combination the run-off could recognize the essential of soil water-groundwater transportation in present saline process,