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| DOI：10.13522/j.cnki.ggps.2019028 |
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| Effect of rainfall on water stability aggregates of crust soil on slope surface |
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CHEN Lin, WANG Jian, SONG Pengshuai, ZHAO Yu, MA Yuhong
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1.Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China; 2.Xi’an Water Conservancy and Soil Conservation General Station, Xi’an 710000, China
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| Abstract: |
| 【Objective】The purpose of this paper is to explore the difference of aggregate distribution and soil erosion resistance in the surficial soil crusts under micro-terrain.【Method】Some experiments were conducted. Artificial rainfall simulation was used to study the change of water-stable aggregates in crust soil under the impact of rainfall. Influenced by micro-topography, surface crust properties show differences. The water-stable aggregates of surface crust soils at different locations on slopes were studied, and the soil samples without crust at the bottom were taken as controls. Study on the Change of Soil Aggregates in Different Crust Types by Yoder Wet Screening Method. 【Result】Under the impact of rainfall, taking 5 minutes of rainfall as an example, crusts at different locations ①Soil water-stable aggregates are characterized by large aggregates proportion. Structural crust contains the largest aggregates, followed by transitional zone and undisturbed soil, and sedimentary crust is the smallest. The proportion of macroaggregates in undisturbed soil, structural crust, transitional zone and sedimentary crust were 37.69%, 41.95%, 37.05% and 28.93% respectively. With the continuation of rainfall, soil macroaggregates in structural crusts and transitional zones increased significantly, while those in sedimentary crusts decreased slightly. ②Average equivalent diameter and geometric average diameter of soil water-stable aggregates vary greatly. The average equivalent diameters of undisturbed soil, structural crust, transitional zone and sedimentary crust are 0.15, 0.19, 0.17 and 0.12 mm, respectively. The geometric average diameters are 0.16, 0.21, 0.19 and 0.14 mm, respectively. The average equivalent diameter and geometric average diameter of water-stable aggregates in structured crust soil are the largest, followed by transition zone and undisturbed soil, and sedimentary crust is the smallest. ③The fractal dimension D of soil water-stable aggregates is different, but the difference is not significant. The fractal dimensions D of water-stable aggregates in undisturbed soil, structural crust, transitional zone and sedimentary crust are 2.725, 2.705, 2.725 and 2.737, respectively. The fractal dimension of water-stable aggregates in sedimentary crusts is the largest, followed by transitional zone and undisturbed soil, and structural crusts are the smallest.【Conclusion】Rainfall strikes disperse large aggregates and enrich small aggregates in the soil surface. The higher the content of macroaggregates, the more stable the soil structure, the stronger the anti-erosion ability; on the contrary, the weaker the anti-erosion ability. |
| Key words: soil aggregates; wet screening method; crust; rainfall duration |
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