Prediction of groundwater inflow rates to longwall coal panels in Central Turkey

Pre-feasibility studies at a coal basin in Central Anatolia indicate mineable resources of about 265 million tons of coal that can be extracted via underground longwall mining during a mine life of 36 years. Since dry working conditions are prerequisite for a safe and operational mining, prediction of the groundwater inflow rates to the underground panels play a critical role. This study predicts groundwater inflow rates to determine dewatering requirements of the underground panels and evaluate anticipated impacts of dewatering on the groundwater resources. To analyze these aspects, the groundwater flow regime was modeled and calibrated under steady-state conditions using the three dimensional groundwater flow model MODFLOW SURFACT. The groundwater inflow rates were evaluated at six critical panel locations. The results indicate that groundwater inflow rates to the panels range from 26 L/s to 130 L/s, based on the location and depth of the panels. The long term impacts of dewatering on groundwater resources were assessed in terms of spring discharges that supply water to local communities and base flow rates to the Porsuk Stream. As a result of dewatering, majority of village water supply springs and fountains will dry up in the area. Furthermore, no baseflow contribution to the Porsuk Stream takes place for dewatering operations conducted at the deeper panels. On the other hand, the baseflow decreases by 33-38% for dewatering of shallower panels.