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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2018-11
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).
The characteristics of gravelly soil physical properties and their effects on permafrost dynamics: A case study on the central Qinghai-Tibetan Plateau
Shuhua Yi1,2, Yujie He3, Xinlei Guo4, Jianjun Chen5,6, Qingbai Wu7, Yu Qin1, and Yongjian Ding1,8,9 1State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, 320 Donggang West Road, 730000, Lanzhou, Gansu, China
2School of Geographic Sciences, Nantong University, 999 Tongjing Road, Nantong, 226007, China
3Chinese Research Academy of Environmental Sciences, No.8 Dayangfang, Chaoyang District, 100012, Beijing, China
4Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, Agrosphere (IBG-3), Wilhelm-Johnen-Straße, 52428 Juelich, Germany
5College of Geomatics and Geoinformation, Guilin University of Technology, 12 Jiangan Road, Guilin, 541004, China
6Guangxi Key Laboratory of Spatial Information and Geomatics, 12 Jiangan Road, Guilin, 541004, China
7State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, 320 Donggang West Road, 730000, Lanzhou, Gansu, China
8Key Laboratory of Ecohydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000, China
9University of Chinese Academy Sciences, Beijing, 100049, China
Abstract. Soils on the Qinghai-Tibetan Plateau (QTP) have distinct physical properties from agricultural soils due to weak weathering and strong erosion. These properties might affect permafrost dynamics. However, few studies have investigated both quantitatively. In this study, we selected a permafrost site on the central region of the QTP and excavated soil samples from 20 cm to 200 cm. We measured soil porosity, thermal conductivity, saturated hydraulic conductivity and matric potential in the laboratory. Finally, we ran a simulation model replacing default sand or silty clay parameters with different combinations of these measured parameters. Results showed that gravel content (diameter > 2 mm) was ~ 55 % on average in soil profile; soil porosity was less than 0.3; saturated hydraulic conductivity ranged from 0.004–0.03 mm s−1; saturated matric potential ranged from −14 to −604 mm. When default sand or silty clay parameters were substituted with these measured values, the model errors of soil temperature, soil liquid water content, active layer depth and permafrost lower boundary were reduced. The root mean squared errors of active layer depths simulated using measured parameters, and the default sand and silty clay parameters were about 0.28, 1.06, 1.83 m, respectively. Among these measured parameters, porosities, which were much smaller than soil textures used in land surface models, played a dominant role in reducing model errors. We also demonstrated that soil water dynamic processes should be considered, rather than using static properties under frozen and unfrozen soil states as in most permafrost models. We concluded that it is necessary to consider the distinct physical properties of soil and water dynamics on the QTP when simulating dynamics of permafrost in this region. It is important to develop methods for systematic measuring physical properties of gravelly soil and to develop a spatial dataset for porosity because of its importance in simulating permafrost dynamics in this region.

Citation: Yi, S., He, Y., Guo, X., Chen, J., Wu, Q., Qin, Y., and Ding, Y.: The characteristics of gravelly soil physical properties and their effects on permafrost dynamics: A case study on the central Qinghai-Tibetan Plateau, The Cryosphere Discuss., https://doi.org/10.5194/tc-2018-11, in review, 2018.
Shuhua Yi et al.
Shuhua Yi et al.
Shuhua Yi et al.

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Short summary
Gravelly soil on the Qinghai-Tibetan Plateau has different thermal and hydrological properties as soils commonly used in modeling studies. We took soil samples and measured their physical properties in laboratory, which were used in a model to simulate their effects on permafrost dynamics. Model errors were reduced using the measured properties, in which porosity played an dominant role.
Gravelly soil on the Qinghai-Tibetan Plateau has different thermal and hydrological properties...
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