Slide 1

Water Utilities and Drought Planning: Indices, Triggers, Stages, and Response David Yates, David Purkey, Liz Mansfield CPASW 7 March 2008 Slide 2 Inland Empire Utility Agency, S. California Regional Utility Alliance in California, CABY Colorado Springs, CO Boston, MA Durham, NC Palm Beach County, FL New York City, NY Portland, OR AwwaRF/NCARThe Water Utility Story NYC IEUA Slide 3 Decision Analysis Approach Slide 4 Water Utilities and Climate Information Streamflow is the primary climate surrogate. Planning is based on assumption of Stationarity Should we assume Stationarity is Dead? Milly et al. 2008, Stationarity Is Dead: Whither Water Management?, Science Slide 5 El Dorado Irrigation District Sac Slide 6 EID- Shared Vision Model Drought Plan Built On: Model of 3-year worst-case dry year sequence Historic hydrology Historic Demands Supply Demand Slide 7 EID- Shared Vision Model Drought Plan Built On: Model of 3-year worst-case dry year sequence Historic hydrology Historic Demands Supply Demand Streamflow PerCap & Pop Reliability Slide 8 Drought Plan Development Estimate water supply conditions Determine savings that each Drought Stage will likely produce Define the indicators and triggers to give expected results (e.g. reliability target) Test when drought conditions are likely to cause operational issues How soon curtailment would have to start to be effective. Slide 9 Shared Vision Model Water supply scenarios, rights and restrictions under low flow conditions Build in drought indices Test drought triggers by various stage scenarios Test various trigger plans, including current plans Userfriendly, transparent, dynamic and consensus-based Slide 10 Drought Plan Indicators Indicators include: Water Yr Type ENSO Reservoir levels Streamflow Define a Supply Remain Index Indicators are modeled in the SVM Slide 11 EID Drought Plan Triggers EID SRI Trigger Plan Summary Table MonthENSOSRI Last month's stage This month's stage MayAny