Hurricane KATRINA Lessons Learned for Managing Risk

Transcription

1 Hurricane KATRINA Lessons Learned for Managing Risk Steven L. Stockton, P.E. Deputy Director of Civil Works U.S. Army Corps of Engineers

2 What Happened? Storm Path from August 23 to 31, 2005 Mon. August 29 Tropical depression Tropical storm Category 1 Category 2 Category 3 Category 4 Category 5 Sun. August 28 Sat. August 27 Tues. August 23

3 Hurricane Katrina at Landfall Date and Time Wind Speed Central Pressure Category Landfall near Buras 6:10 am CDT Aug 29, mph 205 km/hr 920 mb 3 Landfall near Pearl River 9:45 am CDT Aug 29, mph 195 km/hr 928 mb 3

4 Mesh module water surface elevation (63): Hurricane Cat. 3 Storm Surge Cat. 5 Storm Surge > 9 m New Orleans

5 Existing New Orleans Area Hurricane Protection And Levee Damages Legend Breaches Federal Federal Non-COE Non-Federal Damages to System 169 miles (272 KM) of 350 miles (565KM) of levees/floodwalls damaged One Corps 34 Serving of 71 pump the Army stations and damaged the Nation

6 A PROJECT DESIGN FLOWLINE (20 FEET) LONDON AVENUE CANAL FLOODWALL B HURRICANE LEVEE / FLOODWALL (14.0 FEET) INTERIM LEVEL PROTECTION (10.0 FEET) RIVER BANK LAKE PONCHARTRAIN SHORE CANAL ST AT RIVER ST LOUIS CATHEDRAL ESPLANADE AT ST. CLAUDE DERBIGNY AT I-10 GENTILLY BLVD AT ALLEN DILLARD UNIV CAMPUS ST ANTHONY AT WILDAIR DR WAINRIGHT DR AT L. C. SIMON UNO SIDE OF WAINRIGHT DR MISSISSIPPI City of New Orleans Profile 80% of Greater New Orleans BELOW sea level Lake Pontchartrain River Mississippi FLOODWALL ALONG MISSISSIPPI RIVER 23 FT A New Orleans B A B ELEVATIONS IN FEET NGVD

7 Impacted Area Areas to be Repaired Areas with no Significant Damage Non-Federal Levee

8 Industrial Canal

9 17 th Street Canal

10 Damaged Infrastructure

11 Unwatering New Orleans

12 Emergency Levee Repairs

13 Emergency Levee Repairs

14 Debris Removal 49 Million Cubic Yards Removed (54 MCY Total est.)

15 Navigation Restoration

16 Katrina Damages Fatalities: 1420 in 7 states of the U.S. Displaced: >1.5 million people Evacuated: 1.2 million people Estimated Damages U.S.$120 billion Importance of coastal LA Home to 35% of U.S. commercial fisheries Supplies U.S. with 27% of its oil and 32% of its natural gas by its infrastructure Ports rank 1 st in Nation by tonnage Home to 70% of Mississippi River Valley s migratory waterfowl Coastal wetlands dampen hurricane surge

17 15 March 2006

18 Greater New Orleans Hurricane Protection System Status 6 March 2006 Response to date 100 miles of levee/floodwalls restored to design levels 85% of pumping capacity restored 59 contracts issued; utilizing 91% local contractors. Total value of work-$770 million 1 June and Beyond 1 June: All Damaged Levees/Floodwalls Restored to Authorized Design Levels Temporary closure structures on 3 drainage canals installed to protect from storm surge Sep 2007: Entire Hurricane Protection System Restored to Authorized Design Levels Damaged and undamaged levees/floodwalls restored All 5 authorized New Orleans and South East Louisiana hurricane protection projects 100% complete Dec 2007 Hurricane Protection Study complete : $1.46 B Requested Improvements to Protection System (pending supplemental) complete

19 Evolution of New Orleans Hurricane Protection System GAO Report to Congress 28/09/05 Congress authorized in 1965; $85M; estimated completion 1979 Designed for NWS-SPH, ~ Cat 2+ today, return period of about yrs. Basically two alternatives: 1. Two rings of protection: inner ring of 9-13 levees; + outer storm surge barrier with flood gates 2. Inner ring of high levees, Lawsuits (1977) over two-ring plan; Plan 1 abandoned By 1982, the costs rose to~$800m; est completion By 2005, 60-90% of 125 mi levees complete From , Congressional appropriations declined from $15-20M/yr to $5-7M/yr 2002 Corps requested funds for a study to strengthen HPS

20 Why Did The Hurricane Protection System Not Perform As Designed? Event exceeded designed standards Congress authorized protection against category 2+ in 1965 System Incomplete Construction of levees/floodwalls financed over 40 yr. period. Not all were completed by 2005 Structural Failures in Levees/Flood Walls Levee subsidence Levees were below design grade Loss of Coastal Wetlands

21 Hurricane Protection System Performance Review Periodic Review of IPET Reports Independent Commentary National Research Council Independent Review Panel The System The Storm The Performance Consequence Risk Interagency Performance Evaluation Task Force (IPET) Interagency Public Forums American Society of Civil Engineers External Review Panel External Near-real real Time Review of IPET Plans

22 Geotechnical Factors and Behavior Combination of numerical and physical modeling Sophisticated soil-structure analysis will use the Army and RPI centrifuges with support from Geo-Delft Army Centrifuge Overtopping & Scour Piping and Uplift Key Response analyses Weak soil layer

23 17 th 17 th Street Breach Mechanism 17 th Street Canal Breach CL Deflection and Pressure Deflection of I Wall by surge/waves Full hydrostatic pressure along wall Weak clay at levee toe causes failure in subsurface clay layer Soil block from wall back displaced CL Failure and Movement Confirmation in Centrifuge Displacement of wall and part of levee

24 East Breach of IHNC Permanent Repair (New T-Wall T w/original Wall Superimposed) New T-Wall Original Wall New Scour Protection

25 Hurricane Protection System Emergency Improvements

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32 Protection Barriers in the Netherlands

33 Example from Italy: Proposed Venetian Storm Barrier Protection System

34 Example from the U.K.: Thames R. Storm Surge barrier

35 Coastal Louisiana

36 General Lessons Learned Disasters and relief are now globalized phenomena and we need to rethink how we cooperate in prevention as well as reaction Must plan for prevention, preparedness, response and restoration and not just reacting to events. Must manage as a system (IRWM) Non structural behavioral measures alone are not enough for prevention and reaction Structures are critical but also can be dangerous Ecosystem vitality must be integrated into the solutions How to determine what level of risk is acceptable to what population and who will pay We must view the integration of relief, response and prevention as a holistic risk management - in which the citizens actively participate in choosing levels of acceptable risk We all need to learn how to better communicate risk to populations we serve

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