Water management activities involve a complex and interconnected web of science, infrastructure considerations, societal expectations, and institutional limitations that has evolved over time. Much of the water management system's current complexity developed in response to the interests of local water users and land owners, historical water supply and demand issues, political demands, and water quality and environmental considerations. Climate change poses a new set of questions for water managers and may require more flexible solutions than those that have evolved historically. Although the implications of changes in the climate on water supply and demand are recognized (if not well quantified), ongoing changes in temperature and precipitation, as well as the linkages between environmental and societal factors, lead to major uncertainties in future conditions. New tools, techniques, and institutions will be needed to sustain water supplies for communities and watersheds in the future.
People have been managing water and adapting to surpluses and shortfalls since the dawn of civilization, and especially since the early origins of agriculture. There is evidence across the globe of thousands of years of dam-building and canal construction to direct water toward crops of various kinds. Though the tools water managers use today are dramatically more sophisticated than those used in the past and the scale on which water managers work is much larger in almost all cases, the activities are still very much the same: managing floods and shortages (droughts) through harvesting and storing water above or underground, delivering water across long distances through pipelines and canals, and using a variety of technologies to increase water-use efficiency. Over the last one hundred and fifty years, the invention of turbine pumps and the development of multiple sources of energy have led to increased pumping of groundwater and the creation of significant linkages between water availability and energy usage.
The story of adaptation to surpluses and shortages is not new: climate and weather have always varied on timescales ranging from days to weeks to decades and even centuries, and there have always been “surprises” like the dust bowl of the 1930s or the recently discovered fifty-year megadroughts (documented through tree ring studies) in the 1100s.1 But climate change and a variety of rapidly evolving social factors add new dimensions to the challenges of managing water supplies. These challenges derive from the fact that water managers must plan for a future of increasing uncertainties, including potentially escalating storm intensity and changes in flooding and droughts interacting with natural variability on multiple timescales. Changes in the demand for water exacerbate the already complex water management picture, while other social, economic, and technological trends also affect water demand across the United States. For example, rapid changes in water-use patterns are related to changes in social values, such as recent decisions to preserve instream water flows for the environment, recreation, or the use of Native nations. . . .
- 1David M. Meko, Connie A. Woodhouse, Christopher A. Baisan, Troy Knight, Jeffrey J. Lukas, Malcolm K. Hughes, and Matthew W. Salzer, “Medieval Drought in the Upper Colorado River Basin,” Geophysical Research Letters 34 (10) (2007), doi:10.1029/2007GL029988.