关中平原土壤凝结水量及水汽来源特征

Characteristics and source of soil condensation water in Guanzhong Plain, China

为了明确关中平原土壤凝结水量及水汽来源,探究其在水量平衡中的意义,自制开口、上封、下封3种不同类型的微型蒸渗仪,选取典型试验点,采用称重法在2018年9月下旬—10月底及2019年3—5月进行凝结水野外观测。结果表明:监测期内,在无降雨天气下凝结水每日均有发生,开口式、上封式、下封式处理观测的最大日凝结水量分别为0.38、0.27、0.16 mm,表明关中地区凝结水来源以土壤孔隙中的水汽为主,而利用开口式微型蒸渗仪对土壤凝结水的测定结果能够真实反映关中平原土壤凝结水量。监测期内,土壤凝结水量为14.94 mm,与同期降雨量(116.4 mm)之比为12.8%,大气水凝结与土壤孔隙水凝结的贡献比为0.59∶1。

We determined the quantity and source of soil water condensation versus atmospheric vapor condensation in Guanzhong Plain and explored their role in water balance, using three different types of hand-made micro-lysimeters(open-ends, top-seal, and bottom-seal designs). Field monitoring of the vapor condensation process was carried out from late September to late October in 2018 and from March to May in 2019 using the weighing method. Results showed that during the monitoring period, condensation occurred every day without rainfall event. The maximum daily condensation for the open-ends, top-seal and bottom-seal designs were 0.38, 0.27 and 0.16 mm, respectively, indicating that vapor flow in soil pores was the main source of soil water condensation, and that the measurement using the open-ended micro-lysimeter could faithfully reflect the amount of condensation in Guanzhong Plain. During the monitoring period, total soil water condensation reached 14.94 mm, accounting for 12.8% of the precipitation in the same period(116.4 mm), and the ratio of atmospheric vapor condensation to soil vapor condensation was 0.59:1.