Statistically, the greater part of water supply systems' costs is due to distribution. Two classes of models are available for the analysis of distribution networks. First, simulation, the 'hydraulic network balance', treats existing or planned systems whose dimensions and input are known. Simulation has also been extended to include the system's dynamic hydraulic behaviour, tracing also the propagation of water quality. A second class of models utilizes optimization to design a new network. Cost optimal diameters, pumping heads, inflow rates are determined employing principles of Operations Research, observing constraints including pressure and demand, flow velocities, and the hydraulics defined by the simulation model. Once a cost-optimal design has been determined based upon a 'design demand' it may still appear desirable to verify network operation under different demand patterns. KANET offers both, simulation and optimization. Operation of the package is guided by a user interface, facilitated by graphics, a database providing connectivity. The simulation algorithm, a Newton-Raphson iteration scheme solving a set of simultaneous linear equations for unknown flow correction terms, is time extended including the propagation of water quality. Optimization is by four modules. TREEOPT optimizes a branch network using Linear Programming, TREEALL evaluates the total number of branch networks of a reticulate system. For larger networks TREEGEN, a genetic algorithm, improves a population of optimal branch networks converging towards the global. The result may serve as input to FLOWGEN, a second genetic algorithm, performing an optimal adjusunent of flows restoring branch networks to reticulation. The paper is descriptive and does not reiterate mathematical formulations presented elsewhere.
展开▼
