种植条件下土壤水与地下水相互转化研究

Transformation between Soil Water and Groundwater under the Condition of Planting

选择天山北麓平原两种代表性作物冬小麦和玉米,人为控制不同潜水埋深条件下进行了种植试验,分析研究了种植条件下土壤水和地下水相互转化机理。计算了不同潜水埋深条件下冬小麦和玉米各生育期和全生长期的实际蒸发蒸腾量、潜水补耗差、包气带土壤储水量变化量及同期的潜在蒸发量,结果表明潜水埋深对土壤水和地下水相互转化及农业生态环境具有重要影响。引入了包气带-潜水系统水分转化量均衡临界深度(Z0)概念,发现潜水埋深小于Z0时,潜水向土壤水的转化起主导作用,潜水和土壤水同时对作物需水具有重要动态调节作用,潜水埋深越浅潜水的动态调节能力越强,但是潜水埋深过浅又可能引起土壤次生盐渍化等农业生态环境问题;当潜水埋深大于Z0时,土壤水向潜水的转化起主导作用,土壤水对作物需水仍具有动态调节能力,而潜水基本失去或完全失去对作物需水的动态调节作用,但是有利于潜水入渗补给,增加地下水资源。

 Two representative crops winter wheat and corn are selected to be planted under the condition of different buried depth of phreatic water levels in the northern plain of the Tianshan Mountain for studying the mechanism of the transformation between soil water and groundwater. The potential evaporation effective evapotranspiration net recharge and water-storing capacity of the soil in unsaturated zone have been estimated for different buried depth of phreatic water levels in various growth durations and full-bearing periods. The results show that buried depth of phreatic water levels has a very important influence on the agricultural environment and transformation between soil water and groundwater. Z0 the critical depth of the water transformation balance in the unsaturated-saturated system is introduced into this study. When the buried depth of phreatic water level is less than Z0 transformation from groundwater to soil water is dominant. Both groundwater and soil water act as a dynamic regulation on water requirement for crops. The ability of dynamic regulation would be stronger with the rise of the phreatic water level. Some problems however such as soil secondary salinization would come into being if the buried depth of phreatic water level is too shallow. If the buried depth of phreatic water level is much deeper than Z0 transformation from soil water to groundwater is dominant. Although soil water still woke on the dynamic regulation of crops water demand groundwater has lost or almost lost this function. In this case it is very favourable for groundwater to obtain the infiltrated recharge.