Optimal Calibration Method for Water Distribution Water Quality Model

Abstract

A water quality model is to predict water quality transport and fate throughout a water distribution system. The model is not only a promising alternative for analyzing disinfectant residuals in a cost-effective manner, but also a means of providing enormous engineering insights into the characteristics of water quality variation and constituent reactions. However, a water quality model is a reliable tool only if it predicts what a real system behaves. This paper presents a methodology that enables a modeler to efficiently calibrate a water quality model such that the field observed water quality values match with the model simulated values. The method is formulated to adjust the global water quality parameters and also the element-dependent water quality reaction rates for pipelines and tank storages. A genetic algorithm is applied to optimize the model parameters by minimizing the difference between the model-predicted values and the field-observed values. It is seamlessly integrated with a well-developed hydraulic and water quality modeling system. The approach has provided a generic tool and methodology for engineers to construct the sound water quality model in expedient manner. The method is applied to a real water system and demonstrated that a water quality model can be optimized for managing adequate water supply to public communities.

Keywords:

• Water distribution
• Water supply
• Water quality model
• Chlorine decay
• Simulation
• Calibration
• Optimization
• Genetic algorithm

ACKNOWLEDGMENT

Author would like to thank Dr. Walter Grayman and Dr. Lewis Rossman for providing the data used for this research.

Notes

*Negative sign indicates chlorine decay (not growth).