Soil moisture spatial variability in experimental areas of central Italy
Soil moisture spatial variability in experimental areas of central Italy
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DOI：
10.1016/j.jhydrol.2006.09.004
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发表时间：
2007-02-15
影响因子：
6.4
通讯作者：
Moramarco, T.
中科院分区：
文献类型：
--
作者：
Brocca, L.;Morbidelli, R.;Moramarco, T.
了解土壤水分的空间变异性是水文和气候研究的一个重要问题。本文研究了位于意大利中部小流域的不同试验田的土壤水分空间格局。利用便携式时域反射仪(TDR)在9~8800m2的规则网格上测量了近地表土壤体积含水率，并定期重复采样，以研究土壤水分随湿度条件的变化规律。分析了观测数据的统计特性以及统计参数与田间平均土壤含水率的关系。结果表明，平坦地区土壤水分和缓坡地区归一化土壤水分的概率分布均可假定为正态分布。随着平均含水率的增加，方差总体呈减小趋势。此外，考虑到田间平均含水率与变异系数之间的关系，在最坏的情况下，确定了研究区的最佳测量次数为15~35次。对于具有更显著缓解的场地来说，需要的数字越高。这些结果也通过地质统计分析和与地形属性的相关性得到了证实。相关长度随平均面坡度和平均排水方向的增加而增大，变化范围在10~15m之间。地统计学分析表明，当土壤含水率较高时，特定上山面积的自然对数是最好的近地表土壤水分空间预测因子。在此基础上，可以从土壤水分的空间组织上推测地表和地下水分的横向再分配。(C)2006爱思唯尔B.V.保留所有权利。
The knowledge of soil moisture spatial variability is an important issue for hydrological and climatic studies. This paper investigates the soil moisture spatial pattern obtained from spot measurements carried out in different experimental plots Located in small basins of Central Italy. The near-surface volumetric soil moisture content was measured using a portable time domain reflectometer (TDR) over regular grids whose areas ranging in extension from 9 to 8800 m 2. The sampling in each site was periodically repeated in order to investigate the moisture pattern as function of wetness conditions. The statistical properties of the measurements and the relation of the statistical parameters with the field-mean soil moisture content were analyzed. The results states that the probability distribution can be assumed normal for soil moisture in flat areas and for normalized soil moisture in gentle slope areas. A general decreasing trend of variance with increasing mean moisture content was observed. Moreover, considering the relationship between the field-mean water content and the coefficient of variation an optimal measurements number ranging from 15 to 35, in the worse case, was found for the study areas. The higher number was required for the site with more significant relief. These results were also confirmed through the geostatistical analysis and the correlation with the topographical attributes. Specifically, the correlation lengths were found increasing with the mean areal slope and the mean drainage direction and ranging between 10 and 15 m. This is corroborated through geostatistical analysis showing that the natural logarithm of the specific upstope area was the best spatial predictor for near-surface soil moisture when the water volume in the soil is higher. On this basis, the surface and subsurface lateral redistribution of water can be surmised fundamental in spatial organization of soil moisture. (c) 2006 Elsevier B.V. All rights reserved.