To identify the recharge conditions of karst groundwater in mining area by means of groundwater table and water temperature data: A case in Makeng iron mine, Fujian

On the basis of ascertained hydrogeology conditions, the regime of karst groundwater recharge under dewatering conditions in mining area is found out by means of groundwater table and water temperature data.The aquifer, recharged mainly by precipitation infiltrating water, is composed of the Chuanshan group limestone in the Carboniferous system and the Qixia group limestone in the Permian system. The infiltrating water increased because of the mining activity that exposing some caves, leading fissures by collapse in goaf, disturbing of the Quaternary system sediments and blocking of gullies. Fault fracture zone turns the Wenbishan group argillaceous sandstone of the Permian system into aquifer with good aquosity and transmissibility, which leading to the fissure water in the overlying Jiafu group sandstone recharging the karst groundwater via the Xiaoniangkeng fault and F3 fault. The river water in the Ximahe recharges karst groundwater by seepage along the cross part of the riverbed and the F1 fault. The hypothermia water in the deep granite also entering the pit along the F1 and F10 faults.