Climate-Sensitive Water Demand Forecasting: New Tools for Water Managers

Global climate change poses risks to water resources. Most recent research has focused on supply-side changes including reduced snowpack, earlier snowmelt, and more extreme floods and droughts. Yet, along with these shifts in the quantity, timing, and reliability of freshwater supplies, climate change will also have important impacts on water demand. In particular, increased temperatures and altered precipitation patterns will affect plant evaporation and transpiration (ET) rates and thus total outdoor water use. At the same time, a variety of other factors will continue to influence water demand, including population growth; development patterns; industry; and ongoing water conservation and efficiency programs.

Despite the dynamic nature of water demand, the majority of water suppliers still use simplistic calculations based on population projections and historic water demand to simulate future water demand patterns. We will present a new, scenario-based planning tool that integrates many water demand drivers, including climate change, into a simulation of California's future urban water use to the year 2100.

The Urban Water Demand to 2100 model will make it easier for state agencies, regional planning organizations, and individual water utilities to explore scenarios of future water use and identify possible response options. The model can be customized to reflect local or regional population projections, development patterns, water uses, energy requirements, and expected savings from conservation and efficiency measures. Scenario-based planning can help compare potential futures and different response strategies.