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Simulated Dynamics of Soil Water and Pore Vapor in a Semi-Arid Sandy Ecosystem

机译：半干旱沙质生态系统中土壤水分和孔隙蒸气的模拟动力学

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摘要

Understanding dynamics of soil water content (SWC) and pore air relative humidity (RHpa), as influenced by wetting-drying cycles, is crucial for sustaining fragile ecosystems of desert lands across the world and needed for improving the prediction accuracy of global climate change. However, to date, such an understanding is still incomplete. The objective of this dissertation was to examine such dynamics at a typical desert site within the Horqin Sandy Land, located in Mongolian Plateau of north China. The examination was done by using a HYDRUS-1D computer simulation model and the continuous sensor-based soil water data for two calendar years. HYDRUS-1D was selected because it can well mimic the vertically-dominant two-phase (i.e., liquid-vapor) processes of water movement within soils of semiarid sandy ecosystem. The results indicated that vaporization primarily occurred at a depth of around 10 cm below the ground surface. The diurnal variations of the SWC and RH pa in the top 10 cm soils were much larger than those in the soils at a deeper depth. For a non-rainy day, the SWC and RHpa were mainly determined by the relative magnitude of atmospheric temperature over soil temperature, whereas, for a rainy day, the SWC and RHpa were primarily controlled by the rainfall pattern and amount. The retardation role of the top dry soil layer, which is about 10 cm thick and exists most time at the study site, can prevent the beneath moist soils from being further dried up, and thus is beneficial for sustaining the desert ecosystem.
机译：了解受干湿循环影响的土壤水分（SWC）和孔隙空气相对湿度（RHpa）的动态，对于维持全球沙漠土地的脆弱生态系统至关重要，这对于提高全球气候变化的预测准确性至关重要。但是，到目前为止，这种理解仍然不完整。本文的目的是在位于中国北方蒙古高原的科尔沁沙地内的一个典型沙漠地带研究这种动力。通过使用HYDRUS-1D计算机模拟模型和基于连续传感器的两年土壤水数据进行了检查。选择HYDRUS-1D是因为它可以很好地模拟半干旱沙质生态系统土壤中水流动的垂直主导两相过程（即液体-蒸汽）。结果表明，汽化主要发生在地面以下约10 cm的深度。在最深10 cm的土壤中，SWC和RH pa的日变化比在更深的土壤中大。在非雨天，SWC和RHpa主要由大气温度相对于土壤温度的相对大小决定，而在雨天，SWC和RHpa主要由降雨模式和雨量控制。顶部干燥土壤层的阻滞作用（大约10厘米厚）存在于研究地点的大部分时间，可以防止下面的潮湿土壤进一步干燥，因此有利于维持沙漠生态系统。

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  • 作者

    Pedram, Shohreh.;

  • 作者单位

    Old Dominion University.;

  • 授予单位 Old Dominion University.;
  • 学科 Environmental engineering.;Civil engineering.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 310 p.
  • 总页数 310
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 古生物学;
  • 关键词

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