Assessing the Rainfall Implications on Surface Coal Mining Operations: Thar Case Study

Abstract

Rainfall directly impacts the open-pit surface mining operations in the Thar Coalfield, Pakistan. The overall lithology hosting the lignite type of coal seams in the study area includes Dune Sand, alluvium, and soft sedimentary rocks. Due to the presence of three primary aquifers, the strata overlying and underlying the coal seams are under substantial porewater pressure. Additionally, heavy rainfalls in the Thar area lead to the accumulation of water in mines and may cause pit flooding, making it impossible to continue mining activities until the water is pumped out. Pit flooding often results in equipment damage and production delays. The main focus of the study is to investigate the impacts of heavy rainfall on the mining activities at Thar Coalfield. Two major aspects of open pit mining are considered in this study, i.e., production, and dewatering systems. Due to heavy rainfall, a significant production deviation (V) was noticed in comparison to regular months. The quantity of water drained from the pit (Qa) and anticipated inflow quantity (Qt) values were compared for the rainy season and other times. It was observed that heavy rainfall increases the production deviation from the planned targets and also increases the pit dewatering cost. Moreover, this study suggests preventive measures to address potential losses arising from intense rainfall.