Site Type Division and Evaluation of the Waste Dump in an Arid Open-Pit Mining Area—Taking the Treated Waste Dump in Wuhai City as an Example

Abstract

Many problems exist in the ecological restoration of the waste dumps in open-pit mining areas, such as unclear site types of vegetation construction, unsuitable vegetation measures and site conditions, and poor vegetation growth. To resolve these problems, the site type classification and evaluation of the waste dump in the mining area is a key link to speed up its vegetation reconstruction. In this study, the waste dump in Wuhai treated mining area was selected as the test site. A combination of microtopography, slope direction, mulch thickness, soil hardness, soil texture, total phosphorus content, total potassium content, organic matter content, number of vegetation species, and life forms qualitative and quantitative factors were selected. After logarithmic quantification and standardized site factor correlation analysis, principal component analysis, cluster analysis and factor analysis, the site types of the waste dump were classified and evaluated. The results showed that the micro topography, slope direction and mulch thickness were the dominant factors, and they were the main factors influencing vegetation restoration in the study area. According to the combinations of these dominant factors, the waste dump in Wuhai Mining Area was divided into four site type groups and 14 site types. The site quality evaluation of the 14 site types indicated that topographic factors and vegetation factors are the main factors influencing the site quality of the waste dump, and the site quality grades were divided into four relative scores of excellent (comprehensive score greater than 7), good (comprehensive score between 6 and 7), medium (comprehensive score between 5 and 6) and poor (comprehensive score less than 5). Among these grades, 50% of the site types had site quality scores of "medium" or "poor", so the overall site quality of the waste dump in Wuhai Mining Area was below the medium level. On this basis, appropriate vegetation allocation suggestions are put forward in order to provide theoretical support for the ecological restoration in an arid open-pit mining area.