A Review of Our Legacy System, History of Neglect, Current Issues, and the Path Forward for Levee Safety

Transcription

1 4 th NACGEA GEOTECHNICAL WORKSHOP January 29, 2010 A Review of Our Legacy System, History of Neglect, Current Issues, and the Path Forward for Levee Safety Presented by: Leslie F. Harder, Jr., Phd, PE, GE HDR Engineering, Inc. Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Path Forward

2 Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Path Forward What We Have Learned About Our Levees Old, Aging Legacy Systems Are Very Different than Dams

3 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Levees a long history (1600 s 1920 s)

4 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Levees a long history (1600 s 1920 s) What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures

5 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Placement of Hydraulic Fill for Natomas Levee

6 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Natomas Sacramento River East Levee February 1986

7 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures 1928 Flood Control Act Established Federal Interest in Flood Control Structures Authorized Flood Control Projects on Mississippi River Drainage Basin and Sacramento River Other Flood Control Acts and projects to follow Levees Initiation of U.S. Army Corps of Engineers Flood Control Projects (1920 s 1960 s) What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures

8 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures It is commonly acknowledged: Levees Are Designed to Fail Levees are built of soil and only so high - there will eventually be a large enough flood to overtop them when that happens, they commonly fail

9 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Levees Have Many Flaws and do not need to Overtop To Fail What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures Levees Need Flood-Fights to Prop Them Up To Prevent Failure Even in Moderate Flood Stages

10 What We Have Learned About Our Nation s Levees: Old, Aging Legacy Structures California s State Engineer, William Hammond Hall, reportedly stated: There are two kinds of levees, those that have failed and those that will fail. What We Have Learned About Our Levees Old, Aging Legacy Systems Are Very Different than Dams

11 What We Have Learned About Our Levees Old, Aging Legacy Systems Are Very Different than Dams Levees are simpler structures, but their extent and the policies associated with them are much larger and more complex What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Differences Between Levees and Dams Include: Ownership Purpose and Benefits Imposition of Flood Risk Structural River Footprint Height Duration of Water Retention Age Siting Design Criteria Foundation Characterization Structural Composition Environmental Impacts Performance Instrumentation Regulatory Measures to Reduce Risk Improvements and Transfer of Risk Space for Structural Upgrades Performance Expectations

12 What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Design Criteria, Structural Composition =/ Most levees are legacy systems - up to 150 years old Majority of Dams constructed since 1950 s with modern methods What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Duration of Water Retention =/ =/ Levees are only part-time workers retain water for only limited periods (e.g. weeks) during flood events Dams commonly store water year round

13 What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Duration of Water Retention What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Regulatory Measures to Reduce Risk =/ Cannot restrict river systems no real regulation of levees - limited abilities to restrict future development Restrict reservoir if dam does not meet high standards of safety

14 What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Levee Improvements and Transfer of Risk What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Levee Improvements and Transfer of Risk Planned Levee Raise

15 What We Have Learned About Our Nation s Levees: Levees Are Different Than Dams Levee Improvements and Transfer of Risk Planned Levee Raise Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Path Forward

16 Policies of Neglect As population has increased, men have not only failed to devise means for suppressing or for escaping this evil of floods, but have a singular short-sightedness, rushed into its chosen paths. William John McGee, The Floodplains of Rivers, 1891 Floods are acts of God, but flood losses are largely acts of man. Gilbert F. White, 1945 Policies of Neglect For some: the Pre-Katrina attitude to Flood Management

17 Policies of Neglect Levees Just Don t Any Respect! Policies of Neglect Levees Just Don t Any Respect! Bradford Island Sacramento-San Joaquin Delta August 29, 2009

18 Policies of Neglect Not Treating Levees As Systems Policies of Neglect Not Treating Levees As Systems

19 Policies of Neglect Unintended Consequences (1960 s present) 1968 Establishment of FEMA National Flood Insurance Program and selection of 100-year Flood Protection for Preferred Insurance Rates/ Development Limitations 1986 Water Resources Development Act Establishing Nonfederal Cost Sharing for Federal Flood Control Projects Lack of Understanding about Flood Risks Led Communities and Public Agencies to Only Seek Up to 100-year Flood Protection Policies of Neglect

20 Policies of Neglect Continuing Development in Deep Floodplains Policies of Neglect West Sacremento Flood Insurance Policies Residential Structures Another Disconnect: Personal Responsibility 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1, ,904 Number of structures in Inundated Area 747 Number covered by flood insurance

21 Policies of Neglect Policies of Neglect Increasing Flood Damages Source: NOAA Hydrologic Information Center, Flood Losses

22 Policies of Neglect Complacency (Recent past to the present) Unheeded Wake-Up Calls 1993 Midwest Floods 1997 California Central Valley Missouri River, 1993 Policies of Neglect Complacency (Recent past to the present) Wake-Up Call We Couldn t Ignore - Katrina

23 Policies of Neglect Greater Legal Liabilities: Policies of Neglect Current Situation Levees are Integral to Communities: Critical for the Protection of People, Property, and other Infrastructure An unknown number of levees: ~14,000 Miles of Federal Levees Probably >100,000 miles of Non-Federal Levees Unknown Integrity No National Standards, Approaches Risk: A Dynamic that We Can Keep Up With?

24 Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Workshop Current and Future Risks

25 Current and Future Risks LEVEES????? Current and Future Risks LEVEES????? U.S. Dams

26 Current and Future Risks Increasing Justification for Action U.S. Dams Current and Future Risks Increasing Justification for Action U.S. Dams Decreasing Justification for Action

27 Current and Future Risks New Orleans, Pre-Katrina U.S. Dams Current and Future Risks New Orleans, Pre-Katrina U.S. Dams

28 Current and Future Risks Improved Flood Walls at NOLA Industrial Canal Wave/Water Loading During Hurricane Gustav Current and Future Risks Wave/Water Overtopping During Hurricane Gustav

29 Current and Future Risks Current and Future Risks New Orleans, Pre-Katrina 2008 U.S. Dams

30 Current and Future Risks New Orleans, Pre-Katrina U.S. Dams yr Protection in Current and Future Risks The broad problem of flood-loss reduction is that the rate at which flood losses are being eliminated by construction of engineering or land-treatment works is of about the same magnitude as the rate at which new property is being subjected to damage. Gilbert F. White, 1960

31 Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding

32 Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding

33 Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding Current and Future Risks Managing Flood Risk Flood Risk = Probability of x Consequences Flooding of Flooding

34 Current and Future Risks Sacramento River Basin 200 Year Floodplain DAU Population Growth ( ) Red Bluff Chico Percent Growth 100 % % % % % 0-19 % N Colus a 25 Ma rysvill e 61Yuba City Sacramento 93 Current and Future Risks Our Current Future Flood Risks Larger Floods (Climate Change) Aging Levees More People Behind Levees Time

35 Flood Risk Current and Future Risks Critical Levee Repairs Levee Evaluations State/Local Early Implementation Projects Federal Projects Central Valley Flood Protection Plan f Mitigation Banking Flood Corridor Easements Designated Floodways Reservoir Reoperation and Forecast Based Operations Climate Change Adjustments to Flood Hydrology Floodplain Mapping Flood Risk Notifications New Building Standards Emergency Response Plans Emergency Supplies and Stockpiles Improved Inspection Procedures and Reporting Local Agency Reports on Maintenance Local Land Use Agency Formal Risk Acknowledgement Shared Liability between State and Local Agencies Development Restrictions for Urban Areas without 200-year Protection Central Valley Flood Protection Board Review of General Plan Amendments Time / Investment Taking Steps to Reduce Flood Risk from FloodSAFE California RESIDUAL RISK Current and Future Risks Our Current Future Flood Risks Time

36 Current and Future Risks Flood Risks Time Current and Future Risks Flood Risks Time

37 Current and Future Risks Flood Risks Time Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Path Forward

38 Current Issues Levee Vegetation Animal Burrows Climate Change Current Issues - Levee Vegetation from ETL , USACE, April 10, 2009

39 Current Issues - Levee Vegetation Concerns with Vegetation: Obscures view Impedes maintenance Tree blowover Piping along tree roots Impedes channel capacity Promotes local scour Current Issues - Levee Vegetation Concerns with Vegetation: May also impeded flood-fighting

40 Current Issues - Levee Vegetation Concerns with Vegetation: May also impede flood-fighting BUT Current Issues - Levee Vegetation Levee systems also commonly share same space as water conveyance, critical habitat, and urban esthetics and recreation

41 Current Issues - Levee Vegetation For many Levee systems, trees on the waterside slope and bank may provide critical shaded riparian habitat for endangered fisheries Current Issues - Levee Vegetation For many Levee systems, trees may also provide critical erosion protection on the waterside slope

42 Current Issues - Levee Vegetation Bank Erosion Repairs ~ $6,000 per foot Current Issues - Levee Vegetation Bank Erosion 1870/73

43 Current Issues - Levee Vegetation Bank Erosion 1870/ Current Issues - Levee Vegetation Bank Erosion ~900 feet 1870/ ~1500 feet

44 Current Issues Levee Vegetation Animal Burrows Climate Change Current Issues - Animal Burrows Animal burrows in levees are more and more being recognized as a very serious threat to the integrity of the levee

45 Current Issues - Animal Burrows June 2008 Failure of the Pin Oak Levee, MO attributed to muskrat burrowing Current Issues - Animal Burrows February 2008 Failure of the Truckee Canal Embankment, NV attributed to muskrat burrowing

46 Current Issues Levee Vegetation Animal Burrows Climate Change Current Issues - Climate Change Changing Hydrology From: Roos, 2003 Folsom Dam completed

47 Current Issues - Climate Change Changing Hydrology From: Roos, 2003 Folsom Dam completed Current Issues - Climate Change Sea Level Rise 2 ft. 1 ft. Source: IPCC, 2001

48 Current Issues - Climate Change Engineer Circular EC (USACE, July 1, 2009): Incorporating Sea-Level Change Considerations in Civil Works Programs Requires Incorporating Future Sea-level Change Projections into Planning, Engineering Design, Construction, and Operating Projects Requires Consideration of a Range of Projections Requires Determination of Sensitivity of Alternatives to Sea-Level Change Projections, and Consideration of Mitigation Measures Current Issues - Climate Change DRMS Phase 2 Preliminary Estimate of Risk Mitigation Measures to Address Future Sea Level Rise and Island Subsidence April 2007 DRMS and September 2007 CALFED ISB Recommendations for Sea Level Rise: Assume ~90 cm by 2100 Consider at least up to ~140 cm by 2100 Berm to maintain stability/seepage Raise levee to maintain freeboard Sea level rise of 90 cm Existing water level Subsidence Existing levee Costs to Maintain Current Level of Performance for 90 cm SLR over the next 100 years (to ~2100) Per mile cost Total Cost for 500 miles upgrade On Island fill ~ $ 9 million ~$ 4.4 Billion Imported fill ~ $ 24 million ~$ 11.8 Billion

49 It s Always Darkest Just Before it goes Pitch Black Presentation Outline What We Have Learned About Our Levees Policies of Neglect Current and Future Risks Current Issues Path Forward

50 Current Issues - WRDA 2007 Title IX - National Levee Safety Act National Levee Safety Act WRDA Title IX Section 9000 Section 9003: Levee Safety Committee Section 9004: Inventory, Inspection, Database and Assessment Current Issues - National Committee on Levee Safety

51 Thank You