The E ff ect of Various Soil Hydraulic Property Es mates on Soil Moisture Simula ons
The E ff ect of Various Soil Hydraulic Property Es mates on Soil Moisture Simula ons
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各种土壤水力特性估算对土壤湿度模拟的影响
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. McNamara
中科院分区：
文献类型：
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作者：
M. Gribb;I. Forkutsa;Aleshia Hansen;D. Chandler;J. McNamara
基于包气带一维模拟的 321 H 通常用于预测或研究野外和流域尺度的水分、溶质和能量通量。为了使这些模型的结果有用，需要足够准确的土壤水力特性输入，即土壤保水性和水力传导率曲线 θ(h) 和 K(h)。这些特性可以通过实验室和现场实验使用直接测量或反解法来估计。然而，这些方法可能既耗时又昂贵（Dane 和 Topp，2002），并且小样本的实验室测试通常不能反映现场行为（Basile 等，2003）。另外，PTF 允许用户根据有限的信息（如土壤质地、容重和有机碳）快速且廉价地估计土壤水力特性（Wösten 等，2001；Pachepsky 等，1996）。不幸的是，PTF 产生的结果不能充分反映现场行为。尽管实验室测试和 PTF 存在缺点，但许多包气带建模工作仍依赖于它们，因为通常无法进行土壤水力特性的现场测量。然而，当这些信息可用时，我们可以研究实验室测试和 PTF 对土壤水力特性的估计与现场数据的比较效果，以及如何使用现场信息来改进这些估计。在这项研究中，我们研究了通过不同测量和估计技术获得的土壤水力特性对干溪实验流域（爱达荷州博伊西附近的一个非农业山区）内一个小型仪器区域土壤湿度含量的一维模型预测的影响。土壤水力特性是通过原位测量、实验室 MSO 测试、四个 PTF 以及最后使用 HYDRUS-1D 对两次短时间渗透事件的场压头和含水量数据进行反演来估算的（Šimůnek 等人，2005 年）。将这些方法得出的土壤保水曲线与现场数据得出的曲线进行比较，以确定估计值反映现场行为的程度。使用了三种缩放方法来尝试改善各种估计和预测保留曲线与原位数据的拟合。然后将不同的水力参数集用作 HYDRUS-1D 的输入，以确定不同水力特性输入对两个深度土壤湿度和在延长的模拟时间内从土壤剖面底部流出的累积水通量预测的影响。各种土壤水力特性估算对土壤湿度模拟的影响
321 H based on one-dimensional simulations of the vadose zone are routinely used to predict or study fl uxes of moisture, solutes, and energy at fi eld and watershed scales. For the results of these models to be useful, suffi ciently accurate soil hydraulic property inputs, namely the soil moisture retention and hydraulic conductivity curves, θ(h) and K(h), are needed. Th ese properties can be estimated from laboratory and fi eld experiments using direct measurements or inverse solution methods. Th ese methods can be time consuming and expensive (Dane and Topp, 2002), however, and laboratory tests on small samples often don’t refl ect fi eld behavior (Basile et al., 2003). Alternatively, PTFs allow users to estimate soil hydraulic properties from limited information such as soil texture, bulk density, and organic C quickly and cheaply (Wösten et al., 2001; Pachepsky et al., 1996). Unfortunately, PTFs can yield results that do not adequately refl ect fi eld behavior. Despite the shortcomings of laboratory tests and PTFs, many vadose zone modeling eff orts rely on them because in situ measurements of soil hydraulic properties are typically not available. When such information is available, however, we can investigate how well these estimates of the soil hydraulic properties from laboratory tests and PTFs compare with in situ data and how the in situ information can be used to improve these estimates. In this study, we investigated the eff ects of using the soil hydraulic properties obtained by diff ering measurement and estimation techniques on one-dimensional model predictions of soil moisture content in a small instrumented area within the Dry Creek Experimental Watershed, a nonagricultural, mountainous site near Boise, ID. Th e soil hydraulic properties were estimated from in situ measurements, laboratory MSO tests, four PTFs, and fi nally, by inversion of fi eld pressure head and moisture content data from two short infi ltration events using HYDRUS-1D (Šimůnek et al., 2005). Th e soil moisture retention curves resulting from these methods were compared with the curves derived from in situ data to determine how well the estimates refl ect fi eld behavior. Th ree scaling approaches were used in an attempt to improve the fi t of the various estimated and predicted retention curves to the in situ data. Th e diff erent hydraulic parameter sets were then used as inputs for HYDRUS-1D to determine the eff ects of diff erent hydraulic property inputs on predictions of soil moisture at two depths and cumulative water fl ux out of the bottom of the soil profi le for an extended simulation period. The Eff ect of Various Soil Hydraulic Property Es mates on Soil Moisture Simula ons