The storage and aging of continental runoff in large reservoir systems of the world

In this study we analyze the scope and potential impact of reservoirconstruction on the world's river systems. Water storage behind the global population of large dams represents a 700% increase in the standing stock of natural river water, with residence times for individual impoundments spanning less than one day to several years. The imprint of such storage persists downstream. The mouths of several large rivers show a reservoir-induced aging of continental runoff that exceeds three months. Globally, the mean age of river water has likely tripled to well over one month. From both case studies and global synthesis, we find that this aging can lead to significant changes in net water balance, flow regime, reoxygenation of surface waters, and sediment transport. The pandemic construction of large reservoirs represents an important component of the terrestrial water cycle and one that merits due consideration in future global change studies. [ABSTRACT FROM AUTHOR]