Battle of the Water Calibration Networks

TLDR

Calibration aligns model outputs with field data through optimization or manual adjustments, requiring definition of variables, objective functions, data selection, and iterative parameter tuning, and its success depends on modeler expertise and the chosen mathematical procedures. The paper summarizes the Battle of the Water Calibration Networks, aiming to objectively compare different calibration approaches on a real water distribution system. The study employed a calibration framework that defined model variables, objective functions, data sets, and optimization or manual schemes, and involved fourteen teams from academia, utilities, and consultants. The BWCN outcomes were presented at the 12th Water Distribution Systems Analysis conference, and the manuscript reports the exercise and proposes future research directions.

Abstract

Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree. Calibration methods can involve formal optimization methods or manual methods in which the modeler informally examines alternative model parameters. The development of a calibration framework typically involves the following: (1) definition of the model variables, coefficients, and equations; (2) selection of an objective function to measure the quality of the calibration; (3) selection of the set of data to be used for the calibration process; and (4) selection of an optimization/manual scheme for altering the coefficient values in the direction of reducing the objective function. Hydraulic calibration usually involves the modification of system demands, fine-tuning the roughness values of pipes, altering pump operation characteristics, and adjusting other model attributes that affect simulation results, in particular those that have significant uncertainty associated with their values. From the previous steps, it is clear that model calibration is neither unique nor a straightforward technical task. The success of a calibration process depends on the modeler's experience and intuition, as well as on the mathematical model and procedures adopted for the calibration process. This paper provides a summary of the Battle of the Water Calibration Networks (BWCN), the goal of which was to objectively compare the solutions of different approaches to the calibration of water distribution systems through application to a real water distribution system. Fourteen teams from academia, water utilities, and private consultants participated. The BWCN outcomes were presented and assessed at the 12th Water Distribution Systems Analysis conference in Tucson, Arizona, in September 2010. This manuscript summarizes the BWCN exercise and suggests future research directions for the calibration of water distribution systems.