A holistic procedure GLOBAL for the global optimization of water distribution
systems is presented. The procedure identifies an optimal tree layout for the
network and augments it with loop forming links to assure reliability. Thus, the
chosen optimal layout in judiciously subjected to various flow configurations to
find an optimal flow division among pipes for the least cost diameter selection.
Because the problem is nonconvex, two global search schemes, MULITIST ART
and ANNEALING, both within the framework of procedure GLOBAL, are
employed to permit a local optimum seeking method to migrate among various
local minima. A modified Linear Programming Gradient (LPG) procedure is
judiciously employed as local optimizer. An example problem from the literature
is solved using the proposed procedure. The optimal solution has a cost very
near to the theoretical limit for this problem and is significantly smaller than the
ones reported by other researchers.