The safety mining of the 13th coal seam in Baode coal mine on the Ordovician limestone confined aquifer was researched in this paper. The recharge, run off and discharge conditions of Tianqiao spring basin in our studying area, general hydrochemical characteristics and intensive runoff zones characteristics were firstly analyzed. The water yield property, karst water runoff condition evolution, water level variations and seepage field characteristics of Ordovician limestone in our studying area were detaile...