Spatial distribution of soil moisture over 6 and 30 cm depth, Mahurangi river catchment, New Zealand
Spatial distribution of soil moisture over 6 and 30 cm depth, Mahurangi river catchment, New Zealand
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DOI：
10.1016/s0022-1694(03)00060-x
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发表时间：
2003-05
影响因子：
6.4
通讯作者：
David J. Wilson;A. Western;R. Grayson;A. Berg;Mary S. Lear;M. Rodell;J. Famiglietti;R. Woods
中科院分区：
文献类型：
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作者：
David J. Wilson;A. Western;R. Grayson;A. Berg;Mary S. Lear;M. Rodell;J. Famiglietti;R. Woods
对土壤湿度空间分布进行地面测量可能很困难，因为采样基本上是在一个点进行的，并且样本深度和样本间距的选择都会影响测量结果的解释。水文学的兴趣通常集中在根区的土壤湿度。现在可以使用微波遥感方法来解释土壤湿度的空间分布，但是，它们的信号对土壤上部几厘米的湿度做出响应。这些仪器仍在开发中，但围绕其应用的问题之一是如何解释水文背景下的表面湿度。在这项研究中，我们将 0-30 厘米土壤中的土壤湿度测量值与 0-6 厘米土壤中的土壤湿度测量值进行比较，以检查该表面测量值对于根区的代表性。作为综合水文项目的一部分，在新西兰北部 50 平方公里的马胡朗吉河流域的三个牧场进行了详细的土壤湿度空间测量； MARVEX（马胡朗伊河变异实验）。在三个现场，分别使用 30 厘米和 6 厘米电介质仪器进行了三次现场测量。在 0-30 厘米范围内收集数百个湿度测量值的空间网格，并与在 0-6 厘米范围内同时收集的数据进行比较。结果表明，时间和空间问题干扰了两组序列的相关性。暴风雨活动后，与 0-30 厘米相比，快速湿润程度为 0-6 厘米。当在暴风雨后几天对场地进行测量时，含水量响应解耦的一些证据也很明显。还观察到对强降雨的快速但并非不切实际的反应。这意味着，在使用表面土壤湿度测量来推断根区行为之前，需要详细而准确地了解当地土壤条件和健全的土壤水分再分配模型。本研究中无论是从已发表的数据还是现场观察中都无法获得此类知识。在本研究中，在没有适当的先验知识的情况下，通过校准来找到土壤性质信息。
Ground-based measurement of the spatial distribution of soil moisture can be difficult because sampling is essentially made at a point and the choice of both sample depth and sample spacing affects the interpretation of the measurements. Hydrological interest has generally been in soil moisture of the root zone. Microwave Remote Sensing methods are now available that allow the interpretation of spatial distributions of soil moisture, however, their signals respond to moisture in the upper few centimetres of soil. These instruments are still being developed, but one of the questions surrounding their application is how to interpret the surface moisture in a hydrological context. In this study we compare measurements of soil moisture in 0–30cm of soil with those in 0–6cm to examine how representative this surface measure is with regard to the root zone. Detailed spatial measurements of soil moisture were conducted at three pasture sites in the 50km2Mahurangi River catchment of northern New Zealand as part of a comprehensive hydrology project; MARVEX (MAhurangi River Variability EXperiment). In three field sites, on each of three occasions, field measurements were made using both 30 and 6cm dielectric-based instruments. Spatial grids of several hundred moisture measurements were collected over 0–30cm and compared with those collected simultaneously over 0–6cm. Results indicate that temporal and spatial issues interfere with correlation of the two sets of series. Rapid wetting of 0–6cm compared with 0–30cm is seen following storm activity. Some evidence of the decoupling of moisture content response is also evident when sites are measured on days following a storm. Rapid, but not unrealistic, response to intense rainfall was also observed. Implications are that detailed and accurate knowledge of local soil conditions and a sound model of soil water redistribution are required before surface soil moisture measurements can be used to infer root zone behaviour. Such knowledge was not available in this study, from either published data or field observation. In this study, without suitable a priori knowledge, soil property information was found via calibration.