介电管式传感器与中子散射仪同腔共射原位测定农田冰/水含量
首发时间:2015-07-24
摘要:农田环境下同腔共射法在未冻土壤中的交叉检验结果表明:两种仪器具有良好的互换性(R2 > 0.95,RMSE < 0.02 cm3 cm-3)。在冻土中的试验结果表明:该方法能够原位测定冻土未冻水含量和总含水量,通过简单计算进而得到冻土含冰量。由于土壤冻融过程伴随着水分迁移,同腔共射法原位测定冻土冰/水含量显著提高了测量的准确性。获取的冻融信息不仅可为农田越冬期管理(尤其对确定冬灌和春耕时间)提供技术支持,且适用于农田尺度土壤剖面水分的常年监测。
关键词: 土壤含冰量 土壤未冻水含量 土壤总含水量 PVC管 田间测定
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In situ measuring soil ice content with a combined use of dielectric tube sensor and neutron moisture meter in a common access tube
Abstract:For monitoring soil water dynamics in cold regions, the major concerns are not only liquid soil water content (LSWC) and total soil water content (TSWC), but soil ice content (SIC) as well. The field determination of SIC is more challenging than that of LSWC or TSWC and no practical method has been found. This study presents a method that combined a neutron moisture meter (NMM) with a dielectric tube sensor (DTS) lowered in a common access PVC-tube, in which NMM was for determining TSWC and DTS was for LSWC. Consequently, the absolute difference was of SIC. The proposed method was tested in an agricultural field over the winter of 2011-2012. Field calibration and a cross-check showed that DTS and NMM measurements in the common access PVC-tube were very similar (R2 = 0.9503, RMSE = 0.0197 cm3 cm?3) to the volumetric soil water contents (VSWCs) ranging from 0.05 to 0.40 cm3 cm?3. More importantly, the results of overall experimental period confirmed that both sensors had the same responses in the unfrozen layers but different responses in the frozen layers. Based on this, we transformed the measurements of both sensors into SIC. Furthermore, for characterizing the SIC dynamics during the overall experimental period, we presented the curve-based results and the map-based results, respectively. These results verified that the proposed method is feasible to determine the SIC profiles in situ with a major advantage that allows both probes lowering multiple access PVC-tubes at the field scale.
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No.4650579107775214****
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