关键词: 水龄, 管网水质, 逐节点遍历简化算法, 广度优先搜索, 拉格朗日传输算法

Abstract: To calculate the water age in the urban water supply and distribution network，a simplified and junction by junction algorithm based on the definition of the water age itself is designed.Different from the home classical method in which every path from the source to the calculated nodes should be pursued and the“Breadth First Search Method” is used，also not the same as the abroad one “Lagrangian Transport Algorithm” in which each pipe is divided into several segments and the water age calculation is considered as a special case of the water quality simulation，the simplified method has a lot of advantages，such as easier modeling，quicker iterating and more accurate result.So it will be a base theory model and good reference to do a more complicated calculation and simulation of the pipe network water quality.

Key words: water age, water quality in the pipe metwork, simplified and junction by junction algorithm, breadth first search method, Lagrangian transport algorithm