How can the Earth s finite water resources be managed sustainably to meet the growing needs of humans and of nature in ways that avert the looming crisis? The need to find answers to this question has exercised the minds of many scientists, practitioners and policymakers who recognise the urgency of the problems. These concerns have spawned a number of international research initiatives and programs, prominent representatives of which met to review progress and exchange views at an international conference in Bonn, Germany in February 2005.

The pressing water problems must clearly...