A better understanding of the role of Quaternary-era climate change in the development of regional hydrology in the Loess Plateau and the impact on regional ecosystems is needed. In particular, a thorough examination of the permeability and recharge under different conditions in the fifth loess–palaeosol layer is required. The fifth loess–palaeosol layer is located at the southern edge of the Jinghe River in the Guanzhong Basin, and was examined to better understand these conditions. A constant head permeability test was conducted at 11 points that covered different stratum of loess–palaeosol, and 55 corresponding undisturbed soil samples were analysed for porosity, magnetic susceptibility, and grain size. Results showed that: (1) with an increase in hydraulic gradient, the permeability coefficient of the upper part of the loess and the lower part of the palaeosol showed contrasting characteristics – this phenomenon was closely related to climatic conditions during the sedimentary period, post-sedimentary microbial activity, and to certain properties relating to permeability in the strata under similar monsoon effects; (2) the Loess Plateau, alternately dominated by the East Asian summer and winter monsoons, exhibited different grain-size compositions in the sedimentary layer, which, in turn, made the permeability in the loess noticeably more stable than that in the palaeosol; and (3) different aquifer characteristics and recharge conditions between the loess–palaeosol layers can be primarily explained by the intensity of the pedogenesis, which depended on extreme dry-old glacial climates and relatively humid-warm interglacial climates. These findings show that climate change played an important role in influencing hydrological systems in the loess–palaeosol sequence.

中文翻译：

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气候条件对北秦岭黄土高原L5—S5层渗透性和水力特性的影响

需要更好地了解第四纪气候变化在黄土高原区域水文发展中的作用以及对区域生态系统的影响。尤其需要对第五层黄土-古土壤层在不同条件下的渗透率和补给情况进行全面检查。第五黄土-古土壤层位于关中盆地泾河南缘，为更好地了解这些条件而进行了考察。在覆盖黄土-古土壤不同地层的11个点进行恒水头渗透率试验，分析了55个相应的原状土样的孔隙度、磁化率和粒度。结果表明：（1）随着水力梯度的增加，黄土上部和古土壤下部的渗透系数呈现出对比鲜明的特点——这种现象与沉积期的气候条件、沉积后的微生物活动以及与地层渗透性有关的某些性质密切相关。在类似的季风影响下；(2) 黄土高原以东亚夏季风和冬季风交替为主，沉积层的粒度组成不同，这反过来又使黄土的渗透率明显高于古土壤的渗透率；(3) 黄土-古土壤层之间不同的含水层特征和补给条件主要可以通过成土作用的强度来解释，这取决于极端干燥的古老冰川气候和相对潮湿温暖的间冰期气候。这些发现表明，气候变化在影响黄土-古土壤序列的水文系统方面发挥了重要作用。