Change of underground fresh and underground salt water caused by groundwater over-extraction in the eastern Hebei Plain: A case study of the eastern Langfang City and the eastern Cangzhou City

A series of geological environment problems have been caused by groundwater over-extraction in eastern Hebei Plain since 1975. Based on high-density groundwater level measurement data and groundwater extraction data of the eastern Hebei Plain (the eastern Langfang City and the eastern Cangzhou City) in 2017, the authors in this paper analyzed the groundwater exploitation. The underground fresh water in the eastern Hebei Plain was seriously over extracted in recent years by groundwater level analysis of deep and shallow aquifers, exploitation and resource potential. The top and bottom of curtent salt-water system was bounded through comprehensive comparison between deep water sample analysis data and historical background data of water quality, and based on high density electrical prospecting interpretation. Besides, it is concluded that the distribution of salt and fresh water has changed greatly caused by groundwater over-extraction, through comparison with the 1970 s‘ boundary between salt water and fresh water, and the main factors causing the change were analyzed. This research is helpful to understand the development and utilization conditions of groundwater and provide scientific basis for promoting the rational development of groundwater resources in the saltwater area of the eastern Hebei Plain.