22 December 2016

Responses to Global Water Scarcity Lower Global Water Demands from Previous Projections

Integrated modeling with a consistent framework investigates the responses to water availability and demand, and enables investigations of alternative climate mitigation and technology scenarios and their impact.

Folsom Lake, California in 2012 is a visible reminder of how dependent we are on available fresh water for so many uses, from crops, to energy production, to recreation and household use. Finding and gauging the water vulnerabilities and resilience of communities around the world is an important charge for science. Photo courtesy of the U.S. Geological Survey, Department of the Interior/USGS
Science

This research describes a new modeling capability within a fully-coupled energy-land-use-water system of an integrated assessment model for investigating the impact of regional water scarcity. This new capability includes the representation of water availability at the basin scale (a region drained by a river and its tributaries) and three distinct sources of water, renewable surface and ground water, non-renewable groundwater, and desalinated water.

Impact

Long-term projections of water use that do not account for water availability and constraints are likely to overestimate the use of water and scarcity in the long-term. The baseline scenario in this analysis produced global water withdrawals nearly 20% lower by the end of the century than a scenario without water-use constraints. This study highlights the importance of accounting for water as a limiting factor.

Summary

Water is essential for the world’s food supply, energy production (e.g., bioenergy and hydroelectric power), and power system cooling. Water sources include renewable water, non-renewable groundwater and desalinated water. Numerous studies confirm that fresh water resources are already scarce in many regions of the world, which is a threat to human survival as populations grow, prosper, and attempt to adapt to climate change. This study goes further by using the Global Change Assessment Model to analyze interactions between population and economic growth, and energy, land, and fresh water resources simultaneously. The dynamic model used in this study shows all competing claims on water resources—energy, land, and economy. These are reconciled with water resource availabilities across 14 geopolitical regions, 151 agriculture-ecological zones, and 235 major river basins. This study finds that previous projections of global water use are overestimated. Model simulations show that it is more economical in some places to alter agricultural and energy activities rather than use non-renewable groundwater or desalinated water. This study highlights the importance of accounting for water as a limiting factor, particularly in the trade of agricultural commodities and land-use decisions.

Contact
Leon Clarke
Pacific Northwest National Laboratory (PNNL)
Publications
Liu, L, M Hejazi, P Patel, P Kyle, E Davies, and Y Zhou.  2015.  "Water Demands for Electricity Generation in the U.S.: Modeling Different Scenarios for the Water–Energy Nexus."  Technological Forecasting & Social Change, doi:10.1016/j.techfore.2014.11.004.
2015.  "21st century United States Emissions Mitigation could Increase Water Stress more than the Climate Change it is Mitigating."  Proceedings of the National Academy of Sciences 112(34): 10635-10640, doi:10.1073/pnas.1421675112.