Integrating machine learning regression into ordinary co-kriging with related means for improved spatial modeling of acid mine drainage drivers
摘要
Acid mine drainage (AMD) is one of the most severe environmental threats caused by the oxidation of pyrite (FeS₂) in mine tailings, releasing sulfuric acid and mobilizing potentially toxic elements into surrounding ecosystems. Accurate spatial modeling of iron (Fe) and sulfur (S) -the key constituents of pyrite- is essential for predicting AMD risk and informing remediation strategies. However, conventional geostatistical methods such as simple and ordinary co-kriging (SCK, OCK) struggle with undersampled or heterotopically distributed variables, limiting their effectiveness. This study extends ordinary co-kriging with related means (OCK-RM) by using six regression and machine-learning models-Support Vector Regression, Elastic Net, Lasso, Ridge, Stochastic Gradient Descent, and Linear Regression-to estimate the mean relation between Fe and S in a data-driven way. Using the Haveri Cu–Au tailings dataset with strong Fe-S correlation and partial sampling overlap, model performance is evaluated by cross-validated root mean square error (RMSE) and linear correlation (LC). Lasso Regression provides one of the most stable mean relations (LC = 0.80 for Fe and 0.725 for S) and is used to construct the OCK-RM block model. Compared with simple and ordinary cokriging, this ML-assisted OCK-RM variant gives modest but consistent gains in predictive performance and improves the reproduction of the Fe-S relation and AMD-relevant grade–tonnage behavior.