Study On Spatial Heterogeneity And Multifractal Characteristics Of Soil Physical And Moisture In Coal Mining Areas

For a long time,the problems caused by overexploitation of coal in China,such as ground subsidence,falling groundwater level and deterioration of soil properties,have caused adverse effects on the mining ecosystem and seriously threatened the normal production and life of local people.Taking the Xiaoma village coal mine in jiaozuo city as an example,this paper studies the influence of coal mining subsidence on soil physical moisture characteristics in the selected test plots in the subsidence area and non-subsidence area.The physical moisture characteristics of 0-50 cm soil were analyzed by classical statistical analysis.The spatial heterogeneity of soil physical water characteristics was comprehensively analyzed by geostatistical analysis and multifractal analysis,and the following conclusions were drawn:(1)In the subsidence area,the particle size composition of the soil is dominated by powder;with the increase of depth,soil bulk density and field water capacity increase,while soil moisture content,saturated water conductivity and porosity decrease;The multi-fractal characteristics of soil water content,porosity and bulk density weaken,and the spatial difference weakens;The multi-fractal characteristics of soil saturated water conductivity first increase and then decrease,and the spatial difference of field water capacity increases.(2)In non-subsidence areas,the grain size composition of soil is dominated by silt;with the increase of depth,the saturated water conductivity and porosity of soil decrease,and the soil moisture content,soil bulk density and field moisture capacity increase;The multifractal characteristics of soil moisture content,porosity and bulk density weaken,and the spatial difference weakens.The saturated water conductivity gradually decreases,and the spatial difference of field water capacity increases.(3)The content of coarse sand,medium sand and fine sand,saturated water conductivity and porosity of soil in the subsidence area were all greater than that in the non-subsidence area,and the content of silt,water content,bulk density and field water capacity in the subsidence area were all smaller than that in the non-subsidence area.The high value areas of soil water content,field water capacity and soil bulk density were located in the non-subsidence areas,while the high value areas of saturated water conductivity and porosity were located in the subsidence areas.The multifractal characteristics of the water content,saturated conductivity,field water capacity,porosity and soil bulk density in the subsidence area are all greater than those in the non-subsidence area.(4)Seasonal difference analysis showed,in the subsidence,soil water content,soil bulk density and field water capacity reach their maximum values in summer,and soil saturated water conductivity and porosity reach their maximum values in spring;In the whole study area,the total variation of water content and porosity is the largest in summer,the total variation of saturated water conductivity is the largest in winter,and the total variation of soil bulk density and field water capacity is the largest in spring;In the subsidence area,the multi-fractal characteristics of soil water content,porosity and bulk density are more obvious in summer,the multi-fractal characteristics of soil saturated water conductivity are the most obvious in winter,and the multi-fractal characteristics of soil field water capacity are more obvious in spring.