Spatial Variability of Soil Moisture in Mining Subsidence Area of Northwest China

Abstract The current research only investigates the impact of coal mining on deep soil moisture from the perspective of the absolute value of soil moisture. This study applied the combined method of classical statistics and multi-dimensional geo-statistics to analyze the temporal and spatial changes of soil moisture from 0-10m in the mining face of Nalin River No.2 Mine in Northwest China from the perspective of spatial variability. The results of the study showed that in time distribution, on the whole, the soil moisture in the partial areas of the 1-year and the 2-year subsidence area was lower than that in the control area, and the variability increased, but as the subsidence entered a stable period, the degree of variability decreased; vertically observed, in space distribution, the 0-10m soil moisture in the control area had obvious distribution rules with low spatial variability. However, the spatial variability of soil moisture in the 1-year subsidence area and the 2-year subsidence area increased, and the variability showed a trend of increasing continuously with the increase of depth. During the principal component analysis, it was found that the change of soil texture caused by coal mining subsidence, the change of soil pores microstructure caused by geotechnical deformation, as well as the preferential flow caused by changes in groundwater level were the main reasons for the increasing spatial variability of soil moisture. This study revealed the principles of spatial variability of soil moisture in coal mining subsidence areas in Northwest China, which can provide a scientific basis for the restoration of mining areas.