降雨强度与微地形塑造对露天煤矿排土场边坡土壤水分的影响

The Influence of Rainfall Intensity and Micro-topography Shaping on Soil Moisture of Dump Slope in Opencast Coalmine

土壤水分是制约黄土高原地区生态恢复与重建的关键性因子,探究土壤水分的增加和储存是排土场边坡土地复垦和生态系统重建的重要内容。通过塑造水平阶(阶宽1 m,阶长2 m,每个水平阶间距1 m)、鱼鳞坑(长60 cm,宽40 cm,深30 cm,每个鱼鳞坑横排间距1 m,行间距1 m)工程措施,并以未塑造地形作为对照组进行人工模拟降雨试验,选择山西平朔安太堡露天煤矿南排土场边坡为研究区,在模拟降雨期间对土壤剖面不同土层深度(0—10,10—20,20—40 cm)的水分进行动态监测,采用描述性统计分析和方差分析方法,讨论提供降雨强度和微地形塑造方式的土壤水分动态变化和垂直变化特征,并将降雨强度、微地形塑造方式和土层深度对土壤水分的影响大小进行多因素方差分析研究。结果表明:(1)相同微地形塑造下,降雨强度越大,导致土壤含水率的变化量越大,但变化幅度随雨强增大而逐渐减小;高强度降雨使表层土壤含水率变化明显,低强度降雨使深层土壤含水率变化明显。(2)相同降雨强度下,不同微地形塑造能够有效增加土壤水分,且水平阶对土壤水分的增加效果优于鱼鳞坑。(3)随着土层深度的增加,土壤含水率的变异系数逐渐减小,且都属于中等变异。(4)降雨强度、微地形塑造及土层深度对土壤水分的影响极显著(p<0.01),且对土壤水分的影响大小为微地形塑造>降雨强度>土层深度。研究结果表明,在露天煤矿排土场进行微地形塑造有利于土壤水分的补给和存储,对排土场土地整治与生态修复具有积极意义。

Soil moisture is a key factor restricting ecological restoration and reconstruction in the Loess Plateau, and exploring the increase and storage of soil moisture is an important part of land reclamation and ecosystem reconstruction on the slope of the dump. In this paper, the slope of the southern dump of ATB Opencast Coal Mine was selected as the study area through micro-topography shaping and artificial rainfall simulation experiments. For the design of level benches, the step width was 1 m, the step length was 2 m, and the spacing between each level bench was 1 m. For the design of fish-scale pits, the length was 60 cm, the width was 40 cm, and the depth was 30 cm. The horizontal and row spacing of each fish-scale pit was 1 m, and the unshaped terrain was used as the control. Dynamic monitoring of soil moisture was carried out, and descriptive statistical analysis and variance analysis were used to discuss the dynamic changes and vertical changes of soil moisture under different rainfall intensities and different micro-topography. In addition, the effects of rainfall intensity, micro-topography shaping mode and soil depth on soil moisture were studied by multivariate analysis of variance. The results showed that:(1) Under the same micro-topography, soil moisture content increased with the increase of rainfall intensities, and the variation range gradually decreased. High-intensity rainfall caused significant changes in surface soil moisture content, while low-intensity rainfall caused significant changes in deep soil moisture content.(2) Under the same rainfall intensity, different micro-topography could effectively increase soil moisture, and compared with fish-scale pits, level benches could better increase soil moisture.(3) With the increase of soil depth, the coefficient of variation of soil water content gradually decreased, and all belonged to medium variation. Under different rainfall conditions, the vertical variability of soil moisture caused by micro-topography was greater than that of the control.(4) The effects of rainfall intensity, micro-topography and soil depth on soil moisture were extremely significant, and the magnitude of the impact on soil moisture was: micro-topography>rainfall intensity>soil depth. These findings indicate that micro-topography shaping in open-pit coal mine dumps is beneficial to the replenishment and storage of soil moisture, and has positive significance for land remediation and ecological restoration of dumps.