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Efforts to improve water security have led to the development of contamination warning systems aimed at providing early indication of accidental or intentional contamination in drinking water distribution systems. Sensors that detect changes in water quality are a critical component of a contamination warning system. Because the extent of any monitoring system is constrained by a limited budget, focus is placed on optimizing the placement of sensors to maximize contamination detection and protect human health. Robust models and algorithms have been developed to recommend sensor deployment, but many require hydraulic or water quality models. Small utilities typically do not possess the resources to develop these models; therefore, researchers for this study developed the Water Quality Sensor Placement Tool to recommend placement of one water quality sensor without a model or complicated algorithm. This simple graphical procedure allows utility managers to use basic information about the geometry of their network to determine near-optimal sensor placement in limited time without complicated software. [ABSTRACT FROM AUTHOR]

Since the 1960s, researchers have continued to develop new methodologies and algorithms in support of the planning, design, and management of water distribution systems. While initial research focused on modeling the hydraulics of such systems, the 1980s gave rise to additional research focus on water quality issues. More recent research has expanded into issues of system reliability and resilience, energy management, and sensor and chlorine booster station placement. In most cases, researchers have relied on either hypothetical water distribution systems or a handful of actual systems for use as benchmark test systems. Some of the more widely used actual systems include the New York tunnel system and the Hanoi water distribution system. This paper describes the development of a database of several water distribution systems synthesized from a statewide database of systems originally developed by the Kentucky Infrastructure Authority. The developed models include both small and medium networks, as well a range of system characteristics (i.e., system configuration-grid, looped, and branched systems-and system components-number of tanks, pump stations, and supply sources). The development of the database is described, as well as how to gain access to the developed models. All models have been developed to support use by water distribution system modeling software. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new two-stage iterative methodology is presented for upgrading of single-source water distribution networks to achieve redundancy. In the first stage, the existing network is strengthened using linear programming (LP) for a fixed flow distribution obtained using a model that maximizes flow uniformity by minimizing variance of flows in the distribution network. In the second stage, the performance of the network is assessed under single-pipe failure conditions using a node-flow analysis, and the most critical pipe-failure condition having the maximum deficiency in meeting nodal demands is noted. To also make the network satisfactory during the failure of a critical pipe, a new flow distribution is obtained by removing the critical pipe. Constraints for this new flow distribution along with previous flow distribution are then simultaneously considered in a new LP problem. An improved design of the network is obtained by repeating the first stage. This two-stage methodology is continued until the network becomes capable of meeting demands at all nodes during any single link failure. The proposed methodology is illustrated by upgrading a water main system for redundancy. The results of the application demonstrate that the new methodology is more efficient and less computationally demanding as compared to other methodologies used for upgrading of the illustrative water main system. [ABSTRACT FROM AUTHOR]