Taking the example of water supplying project in east Xiamen,it compares and analyses stressed water pipe synthetically by qualitative and quantitative ways from aspects such as economic diameter,limited capacity technical features and comprehensive cost.

In view of the problems existing in gravity conduit design,this paper takes the minimum cost of the gravity conduits as objective function,presents a new optimization design method for gravity conduits by using dynamic programming,and discusses the equivalent diameter,flow distribution,link pipe installation and reliability calculation of the gravity conduits.