Study on overburden aquclude and water protection mining regionazation in the ecological fragile mining area

The study find that the desert area vegetation is dependence the depth of groundwater level. It is revealed that the proper groundwater level for vegetation is 1.5~5.0 m in Yu-Shen-Fu Miming Area in the North Shaanxi Province. The mining fracture zone decreases the ground water level and causes hypergene ecosystems retrogression. So, water level control is the core of scientific mining in the ecological fragile mining area. Mining practice and simulation model tests show that if the thickness of resisting overburden is equal or greater than 33~35 times mining height, coal mining will not decrease the ground water level, if the thickness of resisting overburden equal or less than 18 times mining height, coal mining must destroy aquiclude and decrease the ground water level, and when it is in 33~35 times mining height, the proper mining method as "restricting mining height method" can be use for water protection. The effective approach of scientific mining can be carried by the mining method plan with the water level control as the aim and the subarea of coal mining condition as the base in the ecological fragile mining area.