新疆乌拉泊水均衡试验场凝结水对地下水补给的观测研究

Research on the observation of condensed recharge in a water balance field of Urab in Xinjiang

通过1989～1995年新疆乌拉泊水均衡试验场潜水埋深4m处包气带凝结水对地下水补给的观测:卵砾石2.58mm/a、细砾3.15mm/a、中砂9.90mm/a、细砂35.87mm/a、粉土10.04mm/a。最有利于包气带凝结水形成的时间是每年的4～9月;包气带凝结水量的大小与土体颗粒相对比表面积和渗透系数相关,推测粉砂的凝结水量约为20mm/a,粘性土小于10mm/a;凝结水对地下水补给的最大量约为50mm/a。综合气候和水文地质条件分析,认为本试验研究成果在我国西北干旱区具有代表性,估算西北地区凝结水对地下水的总补给量大于3×1010m3/a,可能大于平原降水入渗量,在某些区域可能是最主要的地下水补给源。

In the period of 1989-1995, observations were carried out in the unsaturated zone above the depth of 4m in a field of water balance with lysimeters in Urab, Xinjiang. Results show that the amount of condensed recharge was significantly depended on the specific surface of media and hydraulic conductivity： cobble mixed with gravel in 2.58mm/a, gravel in 3.15mm/a, middle sand in 9.90mm/a, fine sand in 35.87mm/a, and silt in 10.04mm/a. The extrapolation volume of condensed water for silty sand and cohesive soil were 20mm/ a and less than 10ram/a, the maximum volume was estimated as much as 50mm/a in media. The best period for condensed water formation in the unsaturated zone in an arid desert was from April to September. The account of groundwater resources is more than 3 x 10m3/a in volume in northwest China, which maybe greater than the infiltration of precipitation. Thus the condensed water formed in the unsaturated zone can be the crucial recharge resources in certain arid areas. The observed data with the lysimeter are also analyzed in detail in this article.