Time-series analysis of water demands in three North Carolina cities

The timing of significant shifts in urban water use is highly relevant to water managers, who can better manage demand with an understanding of historic change. This study employs breakpoint and decomposition analyses to explore changes in water use for three North Carolina municipalities between 1990 and 2014. Although water demands were on the rise in each city during the early 1990s, per capita demands began to trend downward in the middle-to-latter years of that decade. The timing of this shift correlates with declines in manufacturing water uses. Per capita demand then remained stable from 2002 until 2007, when rates for all three cities shifted downward once again. This second shift follows the coordination and institutionalization of drought responses at the state level. Only Raleigh experienced another significant decline, with the implementation of conservation pricing in 2010. Moreover, while total withdrawals have remained stable for the cities of Durham and Greensboro since the mid-to-late 1990s, Raleigh saw rapid growth until 2010, when water policies caused the withdrawal rate to drop markedly. In sum, these results suggest that past shifts in urban water use have resulted from the interaction of globalization, water stress, and cross-scale policies. Water managers may wish to consider how globalization and water stress shape demand, both directly and through policy adoption.