Hydrological Characteristics of Ordovician Karst Top in a Deep Region and Evaluation of Its Threat to Coal Mining: A Case Study for the Weibei Coalfield in Shaanxi Province, China

Table 1

Comparative analysis of in situ experiment results and qualitative conclusions.

Qualitative conclusions	Results of water pumping experiment	Results of water drainage experiment	Results of water injecting experiment	Results of water pressure experiment
There are many times of water inrush in Chenghe mining area.	The permeability coefficient of the aquifer ranged from 0.245 to 12.21 m/d.
There are few times of water inrush in Hancheng mining area.			The unit water absorption measured by second water injecting experiment was 0-0.001 L/min.m.m.	The unit water absorption was 0.00074-0.00084 L/min.m.m.
The flow of water inrush in Chenghe mining area is large.		The hydraulic transmission speed of the aquifer is 49.7-520.9 m/min.
The water inrush is hidden in Hancheng mining area.			The unit water absorption measured by the third water injecting experiment was 0.0000311-0.2 L/min.m.m.