Multifractal characteristic of soil pore distribution after long-term recycled water irrigation
GUAN Xiaoyan1,2*, YANG Peiling3, LI liu4, TAN Ya′nan1
1.Department of Irrigation and Drainage, China Insitute of Water Resources and Hydropower Research, Beijing 100048, China; 2.National Center of Efficient Irrigation Engineering and Technology Research-Beijing, Beijing 100048, China; 3.College of Water Resources & Civil Engineering, China Agricultural University, Beijing 100083, China; 4.Huangbizhuang Reservoir Authority in Hebei Province, Shijiazhuang, Hebei 050224, China
Soil structure is one of important indicators for characterizing soil quality. For quantitative characterization of heterogeneity of soil pore distribution after long term recycled water irrigation, the characteristics and heterogeneity of soil pore distribution after recycled water irrigation for various years were analyzed based on KYKY-2800B scanning electron microscope and digital image processing technology and multifractal theory, and then the significance of symmetry of multifractal curve was discussed in this paper. The result showed that the multifractal spectrum could quantitatively describe the heterogeneity of soil pore distribution, and its multifractal singularity spectrum function α-f(α) was continuous and asymmetric, the width of multifractal spectrum Δα could reflect the heterogeneous characteristics of the pore distribution. The width of multifractal spectrum Δα in Beiyechang Irrigation District is generally greater than in Yamenkou Irrigation District, i.e. the pore distribution is more heterogeneous after 30 years recycled water irrigation compared with 50 years recycled water irrigation, but also the number of small pores in Beiyechang Irrigation District was more than the number in Yamenkou Irrigation District. As a result, multifractal parameters can be used as important indicators to characterize the heterogeneity of soil pore distribution quantitatively.
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