Water abundance evaluation of a burnt rock aquifer using the AHP and entropy weight method: a case study in the Yongxin coal mine, China

Severe water inflows to the presence of a burnt rock aquifer in coal mines in the Aai mining area in Xinjiang in China has caused the loss of life and economic damage. Drainage technology represents the main means to control the water management problems in coal mines caused by the presence of burnt rock masses, and the layout of drainage boreholes is determined according to the water abundance of the aquifer. However, existing studies on the water abundance of the burnt rock aquifer in the Aai mining area are insufficient. Using the accessible geological exploration data, a method of water abundance evaluation was proposed in the Yongxin coal mine of the Aai mining area, Xinjiang, China. A model was created using five controlling factors, namely: the thickness of the burnt rock; the core extraction rate; the hydraulic conductivity; the rate of flushing fluid consumption during drilling; and the thickness of the burnt rock aquifer. A thematic map of each factor, drawn using the Kriging function interpolation technique, was divided into five classes. The combined analytic hierarchy process and entropy weight method was applied to calculate the weight of each factor. The water abundance zoning map, constructed via superimposing the thematic map of each factor using the ArcGIS software, was divided into five zones. The map was further verified using the data of pumping test results from three boreholes and mine water inflow from tunnels, and it was thus found that the map was in good agreement with the field data. The present model can effectively evaluate water abundance of the burnt rock aquifer in the Yongxin coal mine of the Aai mining area, Xinjiang, China.