Discussion on methodology of delimiting protection zones for drinking water source in river.

To safeguard public drinking water supply to meet the hygienic standard,the state government has begun to institute regulations for delimiting protective zone of drinking-waster sources.On the basis of the relevant parameters of a river,this paper discusses pros and cons of the methods involved with one-dimensional and two-dimensional models to define the length of protective boundary upstream the drinking water intake in a river,pointing out shortcomings of the existing technical guideline.Suggestions are put forward regarding delimiting proper boundaries upstream either for Grade Ⅰ or Grade Ⅱ of the protection zone of a river.