Effects of seasonal water-level fluctuation on soil pore structure in the Three Gorges Reservoir, China
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Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability. The aim of this study was to investigate the response of soil pore structure to seasonal water-level fluctuation in the reservoir, and particularly, the hydrological change of wetting and drying cycles. Soil pore structure was visualized with industrial X-ray computed tomography and digital image analysis techniques. The results showed that soil total porosity (> 100 μm), total pore number, total throat number, and mean throat surface area increased significantly under wetting and drying cycles. Soil porosity, pore number and throat number within each size class increased in the course of wetting and drying cycles. The coordination number, degree of anisotropy and fractal dimension were indicating an increase. In contrast, the mean shape factor, pore-throat ratio, and Euler-Poincaré number decreased due to wetting and drying cycles. These illustrated that the wetting and drying cycles made soil pore structure become more porous, continuous, heterogeneous and complex. It can thus be deduced that the water-level fluctuation would modify soil porosity, pore size distribution, and pore morphology in the Three Gorges Reservoir, which may have profound implications for soil processes, soil functions, and bank stability.
KeywordsSoil pore structure X-ray computed tomography Image analysis Wetting and drying cycles Water-level fluctuation Three Gorges Reservoir
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This work was funded by the National Natural Science Foundation of China (Grant No. 41771321, 41771320 and 41571278) and Sichuan Science and Technology Program (Grant No. 2018SZ0132). We appreciate Professor Xinhua Peng and Associate Professor Hu Zhou of the Institute of Soil Science, Chinese Academy of Science for guiding on the image analysis.
- Blake GR, Hartge KH (1986) Bulk density. In: Klute A (ed.), Methods of Soil Analysis. Part 1–Physical and Mineralogical Methods., 2nd edition. American Society of Agronomy, Soil Science Society of America, Madison. pp 363–375.Google Scholar
- Chang C, Xie ZQ, Xiong GM, et al. (2011) The effect of flooding on soil physical and chemical properties of riparian zone in the Three Gorges Reservoir. Journal of Natural Resources 26(7): 1236–1244. (In Chinese)Google Scholar
- Danielson RE, Sutherland PL (1986) Porosity. In: Klute A (ed.), Methods of Soil Analysis. Part 1–Physical and Mineralogical Methods., 2nd edition. American Society of Agronomy, Soil Science Society of America, Madison. pp 443–462.Google Scholar
- Ersoy O, Aydar E, Gourgaud A, et al. (2008) Quantitative analysis on volcanic ash surfaces: application of extended depth–of–field (focus) algorithm for light and scanning electron microscopy and 3D reconstruction. Micron 39: 128–136. https://doi.org/10.1016/j.micron.2006.11.010 CrossRefGoogle Scholar
- Gong XM, Teng QZ, Wang ZY, et al. (2016) Throat segmentation of 3D rock image based on skeleton. Journal of Sichuan University (Engineering Science Edition) 48: 100–106. (In Chinese)Google Scholar
- He XB, Feng H, Feng ZD (2005) 3D image of soil microstructure using synchrotron X–ray computed microtomography. Acta Pedologica Sinica 42: 328–330. (In Chinese)Google Scholar
- Li CL (2007) Effect of pore–throat ratio on reservoir permeability. Petroleum Geology and Recovery Efficiency 14(5): 78–79. (In Chinese)Google Scholar
- Ma RM, Cai CF, Li ZX, et al. (2015) Evaluation of soil aggregate microstructure and stability under wetting and drying cycles in two Ultisols using synchrotron–based X–ray microcomputed tomography. Soil and Tillage Research 149: 1–11. https://doi.org/10.1016/j.still.2014.12.016 CrossRefGoogle Scholar
- Pan XJ, Wan CY, Zhang ZY, et al. (2017) Protection and ecological restoration of water level fluctuation zone in the Three Gorges Reservoir. Journal of Landscape Research 9(1): 44–50. https://doi.org/10.16785/j.issn1943-989x.2017.1.011 Google Scholar
- Tang Q, Bao YH, He XB, et al. (2016) Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China. Science of the Total Environment 548–549: 410–420. https://doi.org/10.1016/j.scitotenv.2015.12.158 CrossRefGoogle Scholar
- Tarquis AM, Torre IG, Martín–Sotoca JJ, et al. (2018) Scaling characteristics of soil structure. In: Mcbratney AB, Minasny B, Stockmann U (eds.), Pedometrics. Springer International Publishing AG part of Springer Nature, Switzerland. pp 155–193.Google Scholar
- Zhang JR, Wang JM, Zhu YC, et al. (2017) Application of fractal theory on pedology: a review. Chinese Journal of Soil Science 48(1): 221–228. (In Chinese)Google Scholar
- Zhao D, Xu MX, Liu GB, et al. (2017) Quantification of soil aggregate microstructure on abandoned cropland during vegetative succession using synchrotron radiation–based micro–computed tomography. Soil and Tillage Research 165: 239–246. https://doi.org/10.1016/j.still.2016.08.007 CrossRefGoogle Scholar