Flood Casualties and Damages

Outcome Performance Measure 7.2, Last updated: January 11, 2022 | About this Measure
Targets for reducing flood risk to people and property in the Delta have been achieved through better data and levee investments.

The Measure

Expected annual fatalities and expected annual property damages from flood emergencies in the Delta are decreased.

  • Expectations

    Decreased annual fatalities and annual property damages from flood emergencies, and reduced risk to people, property, and state interests in the Delta.

  • Performance Metrics

    • Expected Annual Fatalities (EAF) in the Delta. This will be evaluated at least every five years.
    • Expected Annual Damages (EAD) in the Delta. This will be evaluated at least every five years.

Expected Annual Damages and Expected Annual Fatalities

The left graph shows the Expected Annual Damages (EAD) (in dollars) due to flooding. The right graph shows the Expected Annual Fatalities (EAF) (in number of fatalities) due to flooding. A 2021 update that accounted for improved hydrology, a decade of levee improvements, and improved levee fragility methodology resulted in a greater than 50% reduction in EAD and EAF.  However, continued investment in Delta flood management is essential as climate change will increase flood risk over time.  Learn more about the risk from climate change in the Delta.

Reducing flood risks to people, property, and state Interests is critical in achieving the coequal goals and protecting the Delta as a place. Evaluating risks to people, assets, water supply reliability, the Delta ecosystem, and the Delta as a place requires considering both the probability and the consequences of flooding. The Delta Stewardship Council developed the Delta Levees Investment Strategy (DLIS) to address the need to evaluate risk in the Delta. It includes probabilistic estimates of expected annual fatalities (EAF) and expected annual damages (EAD).

Expected Annual Damages (EAD)  is an average annual monetary value of current and future losses due to flooding Delta infrastructure and other assets; it includes flood damage to homes and commercial buildings, vehicles, transportation and energy infrastructure, agricultural infrastructure, and lost crops.

Expected Annual Fatalities (EAF) is a risk-based calculation of the average annual number of flood-related fatalities that would be anticipated in the region for the full range of potential flooding conditions evaluated.

A 50 percent reduction in EAD and EAF was selected as the target as this is slightly more than the reduction that should be achieved through required improvements in urban levees to meet Department of Water Resources (DWR) urban level of protection criteria (See Attachment 1). It is expected that improvements to rural levees will add to urban improvements to meet the 50 percent reduction target by 2025.

The Delta Plan promotes several strategies for reducing flood risks in the Delta including continued emergency preparedness, investment in levees, managing land use, and protecting and expanding floodways, floodplains, and bypasses. As these steps are taken, this measure tracks the ultimate desired outcome of those strategies which is reduced risk to people, property, and state interests in the Delta.

The Delta Levees Investment Strategy (DLIS) combined the best available data for calculating the probability of flooding with consequences data to evaluate five risk metrics:

  • Expected annual fatalities (EAF)
  • Expected annual damages (EAD)
  • Potential for water supply disruption
  • Harm to the ecosystem
  • Damage to the Delta as a place

In addition to evaluating risk in the Delta, DLIS provides a framework for investing in levee improvements that balances the needs of the community, water supply, and the ecosystem. Prioritizing limited resources for the Delta is an essential step in reducing risk from flooding for residents of California.

Explore the DLIS Decision Support Tool to learn more

Each chapter of the Delta plan includes strategies to achieve the goals of the plan. These strategies are general guidance on achieving the objective laid out in the plan and in the Delta Reform Act of 2009. Associated with these strategies are recommendations. The recommendations describe more specific and implementable actions to support the achievement of Delta Plan strategies. Strategies and recommendations may also have associated performance measures. Delta Plan performance measures track progress in achieving desired outcomes for the Delta Plan. Below are the strategy and recommendation associated with this performance measure.

Delta Plan Strategy
  • Continue to prepare for Delta emergencies
Delta Plan Recommendation
  • Implement Emergency Preparedness and Response
Metric
  • Expected Annual Fatalities (EAF) in the Delta. This will be evaluated at least every five years.
  • Expected Annual Damages (EAD) in the Delta. This will be evaluated at least every five years.
Baseline
  • EAF for the Delta using best available data as of 2017, as reported in the Delta Levees Investment Strategy final report.
  • EAD for the Delta using best available data as of 2017, as reported in the Delta Levees Investment Strategy final report.
Target
  • 50 percent decrease in EAF by 2025.
  • 50 percent decrease in EAD by 2025.
Data Source

Data is from the Delta Levee Investment Strategy (DLIS)

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