Research status and evaluation methods on the impact of coal mining on groundwater resources in Shaanbei and Shendong coal bases

ZHAO Chunhu; WANG Shidong; JIN Dewu; ZHANG Peiyuan; ZHU Kaipeng; JI Zhongkui; XU Feng

Abstract：The Shendong and Shaanbei coal bases are located in the arid and semi-arid regions of the western region,and are the most prominent areas in China where the contradiction between coal resource development and groundwater resource protection is prominent.The impact assessment of coal mining on groundwater resources is an important part of the environmental impact assessment.It is the basic work for the coal mine to optimize the water conservation min-ing technology according to the requirements of groundwater resources protection and establish the coal develop-ment mode of"determining production by water resources".By systematically analyzing the geological and hydrogeo-logical conditions of Northern Shaanxi and Shendong coal bases,the differences in mining hydrogeological structure,water conservation target layer,water barrier key layer and groundwater loss mode in different mining areas are summa-rized in this paper.The research shows that in the middle to shallow mining areas,the main target layer for water re-tention is the loose aquifer of the Quaternary system,with the loess layer of the Lishi Formation of the Quaternary sys-tem and the red soil layer of the Baode Formation of the Neogene system as the key layers for water retention.In deep mining areas,the loose pore aquifer of the Quaternary system and the pore fracture aquifer of the Cretaceous system jointly constitute the water retention target layer for deep coal resource development,with the sandy mudstone layer of the Anding Formation at the bottom of the Cretaceous system as the key water barrier layer.Based on the com-bination relationship between coal seam mining induced by water conducting fractures and key water blocking layers and water retention target layers in different coal mining areas,five water loss modes of water retention target layers in the Shaanbei and Shendong coal bases are summarized.We have sorted out the relevant requirements and regula-tions for evaluating the impact of coal mining on groundwater resources,combined with the differences in groundwater loss patterns in different mining areas of Shaanbei and Shendong coal bases,and analyzed the technical status and lim-itations of relevant evaluation methods.Finally,in response to the technical requirements for evaluating the impact of scientific coal mining on groundwater resources,we put forward the generalization and numerical treatment of mining induced water conducting fracture zone,the construction method of coal water collaborative dynamic platform model for dynamic calculation of groundwater loss,and three evaluation indexes of the impact of coal mining on ecological water level,water retaining aquifer structure and groundwater resources,so as to provide reference for scientific evalua-tion of the impact of coal mining on groundwater resources and the coordinated development of coal water resources under the situation of"determining production by water resources".