Characteristics of the Longjian spring karst water system

The research area is located in the eastward extension of Xiao mountain in the Qinling Mountain range, with undulating terrain of low mountains and hills. Longjian spring exposes in the Longjian valley near Longjian village in Xin’an county, Luoyang. In order to provide technical support for sustainable development of karst water resources,boundary conditions and hydrodynamic field evolution under manual intervention were systematically studied, taking groundwater systems theory as a guide. According to the regional geology, structure, topography and hydrogeological conditions, this paper analyzed the karst water system, and delimited the range of the system, boundary features and the relationship between the internal and external flow systems. Finally, the Longjian spring was determined to be the only natural drainage. There is no direct hydraulic connection between Longjian spring karst water system and Bailang karst water system. The main recharge sources of the Longjian spring karst water system are precipitation, river infiltration and lateral runoff recharge. The total recharge is 864.42×104 m3/a，and the average annual recharge is 836.81×104 m3/a. The main discharge sources are water resource exploitation and mine drainage. The exploited quantity is 4，117.2×104 m3/a . Because the exploited quantity is greater than the total recharge, the karst water in the research area has been in a state of over-exploitation. The measured annual average decline from 2004 to 2008 was 1.61 m/a. The water level decline was 5.68 m/a in several years (1984 to 2008), and the biggest decline was 17.42 m/a. In addition, the recharge and discharge conditions of the karst water system are discussed, and suggestions for exploitation, conservation, recovery and management of the Longjian spring karst water system are given.