Based on the definition of correlative concepts about an early warning system for water environment security,this paper describes the function and significance of the system construction.

This paper used the difference matrix method in the water environment security assessment and gets a comparatively good result.

Improved analytical hierarchy process was used for weight determining to index system of water environment security evaluation.

Problems and countermeasures of water environment safety in Shandong Province;

The Three-Gorge Project,one of the extremely huge hydroworks in the world,has comprehensive benefits of flood-prevention,electricity-generation and water-borne-transportation,however,due to descending of self-purifying capacity of water,its water environment safety has become the hot spot of concerns in China and around the world.

Jiangnan river web located in Cangnan County,Zhejiang Provice is well developed in industrial and agricultural production,and is densely populated,The river pollution is more and more severe,The water environment safety of the river has been the chief question for industrial development and the people.

To increase the water quantity and improve the water quality, some suggestions about water environmental safety protection and ecology environment protection in this area are provided.

In the model,the three indexes: pollution sources,water quality,zoology are used to establish a comprehensive assessment index system for water environment security assessment of trans-basin water transfer project.