Abstract: In northern Shaanxi Province, China, the ecological environment is poor and the water resource is inadequate. The large-scale coal mining accelerated the loss of water, but how to quantitatively calculate the influence degree is a research hotspot both at home and abroad. Taking the Kuye River basin in northern Shaanxi as an example, this paper creatively put forward that influences of coal mining on regional water resources can be divided into three parts: (1)Destruction of groundwater static reserves: because roof fall happened in the process of coal mining, the water originally stored in the aquifer was emptied in a short time, the destruction effects was permanent and irreversible.(2)Goaf water storage: after the aquifer was destructed, a large amount of surface water and aquifer water flowed into the goaf through cracks, some goaf water's storage time maybe long and some maybe short.(3)Destruction of groundwater dynamic reserves: part of the goaf water was expelled out well, and called as mine water gushing, which can not been drunk by human and animal because of pollution. In order to get the amount of the water damaged by coal mining in watershed, the three parts of water resources was calculated respectively and summed. Next, taking the nearby Tuwei River as compared basin, this paper further calculated the Kuye River natural flow in coal mining period by area ratio method and measured flow ratio in base periods method. The results show that: by 2011, Kuye River groundwater static reserves damaged by coal mining was 1.38×10⁸ m³, goaf water storage was 2.72×10⁸ m³, and groundwater dynamic reserves destruction (mine water gushing ) in 2011 reached 0.62×10⁸ m³, each unit coal consumed about 0.6 m3 water. Taking the nearby Tuwei River as Compared basin, Kuye River natural flow was 17.06 m³·s^-1 in 1980-1998, which was 0.44× 10⁸ m³ higher than the measured runoff; and in 1999-2013 the natural flow was 13.22 m³·s^-1, which is 2.28× 10⁸ m³ higher than the measured runoff. This reduced runoff was mainly caused by soil and water conservation, coal mining, increased production and living water and other factors of Kuye River basin. Finally this paper put forward some measures that helped reduce water resources depletion caused by coal mining in Kuye River. Above all, coal mining is the main reason for water resources reduction in Kuye River basin, and the comprehensive utilization of goaf water and mine drainage must be enhance in future. The new method proposed in this paper, not only has sufficient theoretical basis, but also has simple calculation process, which can be quantitatively used to evaluate the influence of coal mining on water resources in most regions of China.

Key words: northern Shaanxi, coal mining, water resources, groundwater, quantitative recognition, compared basin