EDITOR’S NOTE

From time to time, the Journal of Water Resources Planning and Management publishes a special issue devoted to a select theme. The primary purpose of the special issue is to present exceptional peer-reviewed papers from a single focal area, highlighting recent advances and new solutions to contemporary problems facing water resource engineers, planners, and managers around the globe. This month we are pleased to continue this tradition with an outstanding issue dedicated to the analysis of drinking-water distribution systems.

Steven G. Buchberger, Robert M. Clark, Walter M. Grayman, James G. Uber Five years have passed since the first special issue on water distribution systems analysis appeared in the Journal of Water Resources Planning and Management (Vol. 126, No. 4, July∕August 2000). From one perspective it might appear that relatively little has changed. Analysis of municipal water distribution systems continues to be a staple of the civil engineering profession. Pipe networks are designed, built, and operated to provide a safe, reliable supply of high-quality water to all consumers, even during periods of peak consumption.

From another viewpoint, however, the world is very different today than it was five years ago. Certainly, several industry trends looming on the horizon in the 1990s have zoomed more sharply into focus for both designers and operators of water distribution systems. As forecasted in 2000, the water supply industry is facing key issues across several fronts: (1) regulatory requirements have become more stringent, (2) consumer expectations continue to mount, and (3) economic pressures to improve operating efficiency have escalated. At the same time, technological innovations have brought stunning new capabilities in system-wide monitoring, modeling, and analysis.

While the importance of these critical issues is undeniable, they have largely been eclipsed by a sudden, unexpected, and vital question: How secure is the drinking water supply? In the wake of events from September 11, concerns about the vulnerability of municipal water distribution systems have become a top priority for many utilities around the globe. Owing to their broad spatial coverage and relatively easy access, it is widely recognized that municipal water distribution systems are the most vulnerable component of the public water supply infrastructure.

By virtue of their design, water distribution networks are efficient delivery systems. In the past, accidental contamination of water distribution systems has been implicated in outbreaks leading to serious illness and, at times, death. Fortunately these intrusions are very rare events. Nonetheless, might they signal that the barrier between a safe and an exposed water supply is not so impregnable? To what extent are water distribution systems susceptible to deliberate attacks by malicious groups? What can be done to safeguard the water supply infrastructure and protect the public? Clearly, the definition of a safe and a reliable water supply has assumed a broader meaning in recent years.

With this evolving backdrop, we organized the Sixth Annual Symposium on Water Distribution Systems Analysis at the ASCE EWRI World Water and Environmental Resources Congress, held in Salt Lake City, Utah, June 27 to July 1, 2004. The WDSA symposium featured 12 sessions (including a poster competition) held over four days, with 56 speakers hailing from six continents. Based on the quality of the proceedings paper and the impact of the symposium presentation, several authors were invited to prepare full-length manuscripts for external peer review and possible publication in a special issue of the Journal of Water Resources Planning and Management.

From this process, 10 papers were recommended for publication, and they appear here along with a guest editorial. Seven entries are full papers, two are case studies, and one is a technical note. The wide diversity of these papers (e.g., network reliability, multiobjective analysis, optimal system design, GIS route selection, drinking water treatment, disinfectant residual decay, supply threat assessment, water demand simulation, biochemical sensor placement, transient pipe flow) highlight the rich nature of contemporary problems facing researchers and practitioners dealing with water distribution systems.

Continuing the WDSA tradition, we wish to recognize the Seventh Annual Symposium on Water Distribution Systems Analysis recently held at the ASCE EWRI World Water and Environmental Resources Congress in Anchorage, Alaska, May 15–19, 2005. Looking ahead, we note that the Eighth Annual WDSA Symposium will be held August 27–30, 2006, at the University of Cincinnati. For more details, please visit the WDSA2006 symposium website: http:∕∕www.eng.uc.edu∕wdsa2006∕.

We wish to thank all the participants of the EWRI∕WDSA symposia series for their roles in helping to sustain this annual event. We also recognize the diligent efforts of the external reviewers whose valuable critiques measurably improved the quality of the special issue. Finally, we appreciate the support of Daene McKinney, the Journal editor, and the steady encouragement and wise counsel of Jackie Perry, Managing Editor of ASCE Journals.