The future is drying up: The other water problem

Abstract

Scientists sometimes refer to the effect a hotter world will have on this country's fresh water as the other water problem because global warming more commonly evokes the specter of rising oceans submerging our great coastal cities. Climatologists seem to agree that global warming means the earth will, on average, get wetter. But in the Rocky Mountains, there has been a steady decrease in mountain snowpack-the deep accumulation of high-altitude winter snow that melts each spring to provide the American Southwest with most of its water. There has been less snow, earlier spring melts, and warmer nights. In 2007, Los Angeles went 150 days without a measurable rainfall. This article documents some of the concerns of water managers in the Southwest, focusing on Colorado and Nevada, the reuse of graywater, and measures that are being taken in view of the water rights of the Colorado River. The concept of a "water footprint" similar to that of the "carbon footprint" and the relationship between energy, carbon greenhouse gas emissions, and water is described. There are challenges yet to be addressed for reengineering the water supply and there is the need to rethink the use of water in the face of land use patterns and human population growth. © 2008 ASCE.