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Delta Risk Management Strategy

Delta-Suisun Marsh BranchDepartment of Water Resources

US Army Corps of Engineers

SCWC/SCWD MEETINGJUNE 27, 2007

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DRMSDRMS

Development of DRMS 2000 CALFED ROD Called for Risk

Assessment of Delta Levees 2005 – Levee Risk Analysis Team

– Did Preliminary Work – Seismic only– Also Developed Project Scope for DRMS

2005 – AB 1200 Enacted 2006- Governor’s Executive Order- Delta

Vision

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DRMSDRMS- AB 1200 (CWC 139.2) Sets General

Framework for DRSM- DWR Shall Evaluate Potential Impacts on 50, 100,

200-year projections on possible impacts to Delta from:

- Subsidence- Earthquakes- Floods- Climate Change- & Combination of above

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DRMSDRMS AB 1200 Continued (CWC 139.4)

– DWR/DFG to Determine Principal Options for Delta – DWR to comparatively rate for ability to:

• Prevent Disruption of Water Supplies Derived from Delta• Improve the Quality of Water Supplies Derived from Delta• Reduce Salts, Maintain Water Quality• Preserve, Protect, Improve Delta Levees• Protect Water Rights/Environments of River Systems• Protect Infrastructure within Delta

– DFG shall rate all options for its ability to restore salmon & other fisheries that use the Delta

– Report Due – January 2008

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DRMSDRMS Contract Information

– URS Corporation, Oakland, CA• Over 20 subcontractors

– Approved by DGS - March 6, 2006• 3-year contract• Includes a new LiDAR aerial survey of Delta• Guidance to URS – No new studies, use best available

info, however, some limited exclusions:– Subsidence; Seismic hazard– DRMS report has several new models of Delta operations

(i.e., Risk, Hydrodynamics, ER&R, Water Analysis)

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DRMSDRMSDRMS Technical Memoranda

Risk Analysis Seismology (PSHA) Ecological Impacts (Ecosystem) Subsidence Levee Vulnerability Flood Hazard Wind Wave Analysis Climate Change Water Analysis Module (Hydrodynamics) Geomorphology Impact to Infrastructure Economic Consequences Emergency Response & Repair

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DRMS DRMS Phase 1

• Based on Business-As-Usual Assumptions• Development of a Risk Analysis to Evaluate the Impact to Delta Levees

from:– Floods– Earthquakes– Subsidence– Normal Conditions– Climate Change

• Determine Consequences to Economy & Eco-System based on Risks Found

• Draft Risk Analysis Report submitted April 23 ’07– Public Draft July 2007– Independent Review by CALFED – July – August ‘07

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Summary of Key Findings from Summary of Key Findings from Phase 1Phase 1 (preliminary)(preliminary)160-260 flood-related island failures

expected in the next 100 years

12-15 simultaneous island failures in a major flood event

15- 30% chance of 30+ islands failing simultaneously in a major earthquake in the next 25 years

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Summary of Key Findings Summary of Key Findings (continued)(continued)

Probability of flood-related levee failure – increases by 10% in 2050– Increases by 20% in 2100

Probability of seismic-related levee failure – increases by 12% in 2050 – increases by 27% in 2100

3 feet of sea level rise would push the salt line about 3 miles to the east

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DRMSDRMSPhase 2

Development of Risk Reduction/Risk Management Strategies for Long-Term Management of Delta

– Draft Final Report Due August ’07– Public Review Draft – Oct ’07– Independent Review by CALFED – Oct – Nov ’07– DRMS Final Report – November 2007

Includes Recommendations for Future Work/Studies in the Delta

Will be provided to Delta Vision Blue Ribbon Task Force for Consideration in the “Vision for the Delta”

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Delta Risk Management Strategy

Phase 2: Development and Evaluation of Risk Reduction Strategies

Develop a menu of risk reduction measures that could reduce risk – “building blocks”

Package the measures into different combinations -> “trial scenarios”

Use Risk Model to evaluate potential risk reductions

Evaluate benefits and costs of risk reduction measures

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Potential Risk Reduction Building Blocks:

Improved Levee MaintenanceUpgraded Delta & Urban LeveesEnhanced Emergency Preparedness/ResponsePre-Flooding of Selected Western IslandsLand Use Changes to Reduce SubsidenceArmored Through Delta “Pathway” ConveyanceIsolated ConveyanceElevation of State Highways on PiersArmored Infrastructure CorridorSan Joaquin By-PassSuisun Marsh RestorationCache Slough RestorationFish ScreensReduced Water Exports

Delta Risk Management StrategyDelta Risk Management Strategy

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DRMS Phase 2 DRMS Phase 2 Trial Scenarios Being ProposedTrial Scenarios Being Proposed

Improved Levees

Armored Pathway

Isolated Conveyance

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Thank YouThank You

For more information on the DMRS work, please see the DRMS web site at: http://www.drms.water.ca.gov/