Groundwater quality monitoring and assessment

Because of its wide availability,good quality and cost-effective for the development,groundwater has been an important source for water supply in the world.Groundwater accounts for more than half of the total water supply and provides important source of irrigation water during dry period in North China.However,the quality of groundwater is under great pressure of pollution from agricultural,industrial and domestic sources.Groundwater quality monitoring is the only reliable method to assess the groundwater quality status and serves as an early warning system to protect water supply sources.It provides unbiased scientific information for decision makers,water managers and water users for better management and protection of groundwater resources.The largest ongoing campaigns on groundwater quality monitoring and assessments are the groundwater monitoring for implementing European Union Water Framework Directive in Europe and the National Water Quality Assessment program in the United States of America.In this paper,the state of the art of groundwater quality monitoring in the world and methodologies for groundwater vulnerability assessment,pollution sources rating and groundwater pollution risk assessment were reviewed.Groundwater vulnerability map provides important information for land use planning and water supply sources protection.Groundwater pollution sources rating indicates most hazardous pollution sources and therefore provides a priority list for controlling the sources of pollution.Groundwater pollution risk map indicates the areas of potential serious pollution and can be used as a basis to locate sampling sites for groundwater pollution monitoring.These methods have been applied to the Urumqi River Basin,Beijing Plain and Jinan Karst Spring Catchment and presented in subsequent papers.