The face of hydrologic science is changing rapidly, on national as well as on international scales. The increasing complexity of the problems hydrology is asked to investigate in research and practice today often requires solutions that can no longer be obtained by a single hydrologist, but require a multidisciplinary team. One consequence of this trend is the establishment of initiatives that help formulate and implement science programs to engage and energize the scientific community toward achieving major advances. The IAHS Decade on Predictions in Ungauged Basins (PUB) is an initiative of the International Association of Hydrological Sciences (IAHS) <Sivapalan et al., 2003> to advance our ability to make reliable predictions in ungauged basins. Within PUB, the drainage basin (at various scales) is seen as the element that integrates all aspects of the hydrological cycle within a defined area that can be studied, quantified, and acted upon.