Abstract:

Dezhou City is in a typical Yellow River downstream alluvial plain pore water hydrogeology area where the distinct characteristics of water environment is comprised of salt water and fresh water,so that the natural aquatic environment condition of underground fresh water is rather sensitive and fragile. The continuous exploitation of the groundwater brings great changes in the hydrodynamic force field and hydrochemical field in this area. Based on the monitoring data of groundwater quality in Dezhou City from 1996 to 2007, the authors discuss water quality characteristic and analyze the water quality evolution of shallow groundwater. Results indicate that the water quality of shallow groundwater evolves constantly, in which the water quality index of total hardness, degree of mineralization and Cl^- changes obviously. As diminished mineralization of groundwater caused by the change of the hydraulic force field, the total hardness and degree of mineralization decrease to some extent and the water quality has a tendency of desalinization in the area of Qihe County and Suliuzhuang Town of Xiajin County. Because of strengthening mineralization of groundwater caused by the change of the hydraulic force field, the total hardness and degree of mineralization increase to some extent and the water quality has a tendency of salinization in Ningjin County and Zhangzhuang Town of Yucheng City. According to the groundwater quality evolution tendency in study area, water adjustment measures have been put forward which may make the brackish water evolve into fresh water.

Key words: alluvial plain in the downstream of Yellow River, Dezhou City, groundwater, water quality evolution