In this paper, we use the standard deviation method and the fixed mass method to study the self affine fractal and multi fractal features along two topographic profiles across different tectonic geomorphic elements in...In this paper, we use the standard deviation method and the fixed mass method to study the self affine fractal and multi fractal features along two topographic profiles across different tectonic geomorphic elements in the Tianshan area of Xinjiang region, China. The results show that in the studied scaling range, the two profiles display different scaling fractal features, and the form and value range of multi fractal spectra D q also show different characteristics. The study suggests that the landforms are not completely random, but are deterministically random. The fractal dimension values in different scaling ranges express the mode, intensity and spatial dimension of the endogenic and exogenic processes. Meanwhile, a boundary point between the macroscopic and microscopic scales of geomorphic process is suggested to be about 5 km. These results are of significance in quantitative study of geomorphic dynamics.展开更多
The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hinde...The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.展开更多
基金Theworkisapartoftheresearchproject (2 0 0 0 0 7)supportedbytheEarthquakeScienceFoundationofXinjiangUygurAutonomousRegion China .
文摘In this paper, we use the standard deviation method and the fixed mass method to study the self affine fractal and multi fractal features along two topographic profiles across different tectonic geomorphic elements in the Tianshan area of Xinjiang region, China. The results show that in the studied scaling range, the two profiles display different scaling fractal features, and the form and value range of multi fractal spectra D q also show different characteristics. The study suggests that the landforms are not completely random, but are deterministically random. The fractal dimension values in different scaling ranges express the mode, intensity and spatial dimension of the endogenic and exogenic processes. Meanwhile, a boundary point between the macroscopic and microscopic scales of geomorphic process is suggested to be about 5 km. These results are of significance in quantitative study of geomorphic dynamics.
基金Under the auspices of the Natural Science Foundation of China(No.42272299)The Key Projects of Jilin Provincial Department of Science and Technology(No.20240203004NC)+1 种基金National Key Research and Development Program of China(No.2022YFD1500500)Graduate Innovation Fund of Jilin University(No.2024CX111)。
文摘The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.
