Abstract: Dewatering tests of the Ordovician limestone aquifer were conducted in order to further examine the hydrogeological conditions and evaluate the influences of Ordovician limestone aquifer for mining of lower group of coal seams in the Nantun Coal Mine. The existing hydrogeologcal observation holes are used to carry out the dewatering tests. Three falls in groundwater levels were performed in the tests. Simulation analysis was carried out by using the software of the GMS,which can be used to ident...