Soil seal development under simulated rainfall: Structural, physical and hydrological dynamics.
Soil seal development under simulated rainfall: Structural, physical and hydrological dynamics.
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DOI：
10.1016/j.jhydrol.2017.10.073
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发表时间：
2018-01
影响因子：
6.4
通讯作者：
Ritz K
中科院分区：
文献类型：
--
作者：
Armenise E;Simmons RW;Ahn S;Garbout A;Doerr SH;Mooney SJ;Sturrock CJ;Ritz K
x射线CT有效地量化了土封/结皮厚度。在封印层内显示出不同的微形态带。降雨对水分在土壤中的输送和滞留有强烈而迅速的影响。假设存在与土壤有关的雨滴冲击阈值。该研究通过使用x射线计算机断层扫描（CT）的新方法，为降雨引起的密封形成提供了新的见解。到目前为止，密封和结壳厚度的直接量化主要是通过对密封/结壳表面的目测，还没有定量的方法来估计这一重要性质。对x射线CT图像进行定量分析，得出密封和地壳厚度的正式测量。在实验室建立了一个因子试验，用开盖的微型容器装土。土壤类型（粉质粘土壤土- ZCL、砂质粉质壤土- SZL、砂质壤土- SL）和降雨持续时间（2 ~ 14 min）是研究的主要因素。地表密封的形成是由人工降雨事件引起的，其特征是持续时间不同，但动能、强度和雨滴大小分布是恒定的。利用CT扫描所得的土壤孔隙率来量化降雨引起的地表封印的厚度，并揭示随着降雨持续时间的增加，时间封印的微形态变化。此外，通过测量水滴渗透时间（WDPT）和非饱和导水率（Kun），研究了发育中的密封件的拒水性和入渗动力学。检测到的密封厚度范围为0.6 ~ 5.4 mm。土壤质地特征和有机质含量在降雨形成的封印过程中起主要作用，土壤颗粒越粗，有机质含量越低，封印越厚。土壤孔隙度随深度变化有两种不同趋势：1)土壤孔隙度在近地表最低，随深度增加而不断增加，直至与原状土壤孔隙度中位数相等；ii)与未扰动土壤的中位数孔隙度相比，ZCL和SL在土壤表面以下0.24-0.48 mm处的孔隙度减少幅度最大。这种对比行为与不同土壤性质的封印形成动力学和过程有关。降雨引起的地表封闭对土壤水文行为（以WDTP和Kun为代表）的影响是迅速而实质性的：在2 - 9 min降雨量之间，所有土壤的Kun平均减少了60%，并且在SZL和ZCL中发现了拒水表面。这突出表明，农业土壤的直接表面条件涉及降雨引起的结构密封对土壤作为水库的整体能力有很强的影响。
X-ray CT was effectively used to quantify soil seal/crust thickness. Different micro-morphological zones within seal layers were revealed. Rainfall had a strong and rapid impact on water transport and retention in soil. The existence of a soil-dependent raindrop impact threshold was hypothesized. This study delivers new insights into rainfall-induced seal formation through a novel approach in the use of X-ray Computed Tomography (CT). Up to now seal and crust thickness have been directly quantified mainly through visual examination of sealed/crusted surfaces, and there has been no quantitative method to estimate this important property. X-ray CT images were quantitatively analysed to derive formal measures of seal and crust thickness. A factorial experiment was established in the laboratory using open-topped microcosms packed with soil. The factors investigated were soil type (three soils: silty clay loam – ZCL, sandy silt loam – SZL, sandy loam – SL) and rainfall duration (2–14 min). Surface seal formation was induced by applying artificial rainfall events, characterised by variable duration, but constant kinetic energy, intensity, and raindrop size distribution. Soil porosities derived from CT scans were used to quantify the thickness of the rainfall-induced surface seals and reveal temporal seal micro-morphological variations with increasing rainfall duration. In addition, the water repellency and infiltration dynamics of the developing seals were investigated by measuring water drop penetration time (WDPT) and unsaturated hydraulic conductivity (Kun). The range of seal thicknesses detected varied from 0.6 to 5.4 mm. Soil textural characteristics and OM content played a central role in the development of rainfall-induced seals, with coarser soil particles and lower OM content resulting in thicker seals. Two different trends in soil porosity vs. depth were identified: i) for SL soil porosity was lowest at the immediate soil surface, it then increased constantly with depth till the median porosity of undisturbed soil was equalled; ii) for ZCL and SL the highest reduction in porosity, as compared to the median porosity of undisturbed soil, was observed in a well-defined zone of maximum porosity reduction c. 0.24–0.48 mm below the soil surface. This contrasting behaviour was related to different dynamics and processes of seal formation which depended on the soil properties. The impact of rainfall-induced surface sealing on the hydrological behaviour of soil (as represented by WDTP and Kun) was rapid and substantial: an average 60% reduction in Kun occurred for all soils between 2 and 9 min rainfall, and water repellent surfaces were identified for SZL and ZCL. This highlights that the condition of the immediate surface of agricultural soils involving rainfall-induced structural seals has a strong impact in the overall ability of soil to function as water reservoir.
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影响因子：
6.1
作者：
BISDOM, EBA;DEKKER, LW;SCHOUTE, JFT
通讯作者：
SCHOUTE, JFT
影响因子：
5.4
作者：
Assouline, S;Mualem, Y
通讯作者：
Mualem, Y
影响因子：
6.2
作者：
Bedaiwy, M. N. A.
通讯作者：
Bedaiwy, M. N. A.
影响因子：
2.9
作者：
Bresson, LM;Moran, CJ;Assouline, S
通讯作者：
Assouline, S
DOI：
10.2136/sssaj1982.03615995004600050040x
发表时间：
1982-01-01
影响因子：
2.9
作者：
ALDURRAH, MM;BRADFORD, JM
通讯作者：
BRADFORD, JM