A generalized reduced gradient approach to expansion of water distribution networks

The paper explores the use of the generalized reduced gradient method (GRG) in the design of expansion in water distribution networks. In the optimisation model, the objective function includes capital cost of pipelines and operating cost of pumping stations. The main constraints are a set of nonlinear hydraulic equations, upper and low bounds of diameters, and a minimum requirement of pressure head at all nodes. A modified Newton-Raphson technique is used in the hydraulic simulation to accelerate calculation and the convergence and consistency of the algorithm is investigated. An extension of the method that includes multiple demand loadings is also described.