陇中黄土高原土壤水分变化特征及其机理分析

doi:10.7522/j.issn.1000-694X.2013.00292

摘要/Abstract

摘要： 基于兰州大学半干旱气候与环境观测站（SACOL）2010年全年的观测资料，对陇中黄土高原半干旱区土壤水分的年变化和日变化特征进行了研究，并通过计算水汽通量与蒸散量，探讨了土壤-地表-大气间水分的交换和运移机理。结果表明：土壤湿度的季节变化主要受降水影响，各季节的平均土壤湿度均呈现出表层和深层低、中间层高的特点，最高值出现在地下10 cm附近；在无降水的情况下，土壤5~20 cm处的含水量呈现出夜间逐渐降低、白天逐渐上升的波形变化，这种变化与土壤水汽通量具有很好的一致性，而水汽通量的方向则受温度梯度的影响；在白天，地表温度高于气温与较深层地温，水汽在向空气蒸散的同时也由地表流向土壤深部，夜晚地表温度则低于较深层地温，水汽由土壤深部流向地表。因此土壤内部的水分蒸发主要出现在夜晚，且主要发生在地表40 cm以内的土壤孔隙中，而白天地表的实际蒸发主要存在土壤浅层0~5 cm，5 cm以下土壤水分的蒸发十分微弱。本研究结果对于改进半干旱区陆面计算模式以及当地的生态环境建设具有一定的参考价值。

关键词: 土壤水分, 温度梯度, 黄土高原, 半干旱区

Abstract: With the data collected at the Semi-Arid Climate Observatory and Laboratory of Lanzhou University (SACOL) in the whole year of 2010, we analyzed the annual and diurnal variations of soil moisture in Central Gansu, a part of the semi-arid Loess Plateau. The transport mechanism of soil moisture was explored by calculating water vapor flux and evaporation, too. The results showed that the seasonal changes of soil moisture were strongly influenced by precipitation, and the seasonal average data showed that the characteristics of surface and underlying layer was more obvious than that of middle layer. The highest value of soil moisture was found at about 10 cm under the surface. In the days without precipitation, the soil humidity changed in a waveform as it gradually reduced at night and rose gradually in the daytime. That change was in good agreement with soil water vapor flux and the direction of vapor flux was controlled by temperature gradient. In the daytime, water vapor flew to deeper soil and to air from the surface where the temperature was relatively high, and it flew to the surface with a lower temperature from deeper soil at night. So the evaporation of deeper soil occurred mainly at night, and it appeared in soil pores within 40 cm below the surface. In the day, the actual evaporation mainly came out in soil pores within 0-5 cm below the surface while the evaporation was very weak under 5 cm. Results of this study may have some certain reference value for improving the semi-arid area land surface model, and making the local ecological environment more beautiful.

Key words: soil moisture, temperature gradient, Loess Plateau, semi-arid

中图分类号:

S152.7

李德帅, 王金艳, 王式功, 李振朝, 尚可政, 闭建荣. 陇中黄土高原土壤水分变化特征及其机理分析[J]. 中国沙漠, 2014, 34(1): 140-147.

Li Deshuai, Wang Jinyan, Wang Shigong, Li Zhenchao, Shang Kezheng, Bi Jianrong. Soil Moisture Characteristics and Analysis on Its Moving Mechanism in Central Gansu, a Part of the Semi-arid Loess Plateau[J]. JOURNAL OF DESERT RESEARCH, 2014, 34(1): 140-147.

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