Morphometric characterization of artificial post-mining landforms and natural landforms using a Geographic Information System.

摘要

Modern gold mining operations in Nevada produce new topographic landforms that are required to be reclaimed under federal and state regulations. Such landforms include waste rock, spent heap leach, and tailings facilities. Reclamation involves reducing slope angles and establishing vegetation as a means of stabilizing slopes with the long-term goal of creating a self-sustaining ecological community. Older methods of reclamation produced landforms that differed visually from their surroundings. Increasingly, post-mining landforms are constructed to blend in with their surroundings. Such designs are intended to minimize the visual impact to the environment by constructing landforms to imitate the surrounding topography. This study used an automated approach to compare three types of landforms: natural landforms unaffected by mining, post-mining landforms that have been recontoured to blend in with the surrounding topography, and post-mining landforms that have not been designed to blend in with the surrounding topography. Descriptive statistics were calculated for second order derivatives of elevation, which were derived using a Geographic Information System. Multinomial logistic regression analysis indicated that standard deviation of overall, profile, and plan curvature were the most important variables for discriminating among the three types of landforms, while mean plan curvature, skewness of profile curvature, and kurtosis of all three types of curvature were of secondary importance. Using these criteria, artificial landforms that were designed to look natural exhibited morphometric characteristics midway between those of natural landforms and those of artificial landforms not designed to look natural. Quantitative methods of assessing landform shape have numerous advantages over conventional visual comparisons: their numerical representation makes statistical comparison possible, the methods can be easily documented leading to repeatability amongst observers, and they are more objective than qualitative methods. Mining companies and management agencies can take advantage of the methods utilized in this study to gauge the degree of similarity between landforms that have been recontoured to look natural and nearby landforms unaltered by mining.