UNDER

KEY: Surge water flow Wind direction IF GEORGES HADN’T TURNED Model hurricane track

New Orleans most recently dodged catastrophic MANDEVILLE flooding in 1998, when Hurricane Georges cut across the Gulf of Mexico on a beeline to the mouth of the . As half the SLIDELL population fled, the storm veered to Pearl the east and made landfall in Mississippi. River The hurricane caused flooding in St. Bernard Parish and also pushed Lake Pontchartrain 3 SLIDELL SOAKED Large parts of Slidell would waves from Lake Pontchartrain be inundated, but the waters would recede rapidly with no up against its south shore levees, 4 LAKE LEVEES HOLD levees to contain them. Winds on the west side would leaving many to ponder: push water against the What if? hurricane-protection levees. Rigolets

5 ST. CHARLES SUBMERGED Here, water in the lake would reach heights of 3-8 feet above normal, spilling into wetlands and towns in St. Charles Approximate and St. John parishes. The water would diameter of be deepest near the river levees. hurricane’s eye Chef Menteur Pass LAPLACE

EASTERN No flooding at UNO sippi River sis is Intracoastal Waterway M

KENNER Over 8 feet Over 8 feet METAIRIE Over 8 feet NORCO 4-8 feet Lake Mississippi River-Gulf Outlet Borgne 4-8 feet 6 GRAVITY’S GATEWAY NEW ORLEANS Relentless winds from the stalled hurricane 9TH WARD push a dome of water 14 feet above sea level at the levee. The model says that water Dry land on ST. BERNARD would top low levees and floodwalls and HARAHAN Metairie Ridge move east into Jefferson and Orleans Less than 4 feet PARISH parishes. Jefferson Parish officials say some Lac des Allemands areas would be sandbagged to 10 feet but 7 FILLING THE BOWL 2 PUMPED UP LAKE protection would be lower near the river. With the storm stalled, water continues to pour WEST BANK Easterly winds in advance of the storm would pump into Jefferson and Orleans, filling the bowl with water from Lake Borgne and from Breton and as much as 8 feet of water until it reaches Chandeleur sounds into Lake Pontchartrain, raising natural ridges or the Mississippi River levees. the lake’s surface by 5 feet.

MISS. Winds ALA. pushing Lake water H into lake LA. Pont. FLA. Lake Cataouatche r New Orleans e MISS. ALA. GA. v i R Clockwise high- LA. i 1 FLA. p pressure winds p THE MODEL i s A computer model designed by LSU 30°N s Counter- i Gulf of Mexico s scientists Joseph Suhayda and Vibhas s clockwise i Lake Lery hurricane Aravamuthan and used by government M 100 miles winds agencies to prepare evacuation plans shows 29°N what would have happened if Georges had Actual Georges not turned. This scenario assumes that the path storm continued on the track and intensity 28°N forecast by the National Hurricane Center on Saturday, Sept. 26, 1998, at 4 a.m. In the Gulf of Mexico model, Georges intensifies to a Category 3 27°N Model with 115-mph winds when it makes landfall Georges just west of the mouth of the Mississippi. path During the next two days, it moves slowly 50 miles 26°N Lake Pontchartrain EASTERN BULLARD AVE. northwest, weakening to a Category 1 and Sept. 26 at 4 a.m. NEW ORLEANS EXPLAINING Cross-section of READ BLVD. stalling over eastern New Orleans. KENNER CROWDER 90°W 89°W 88°W 87°W 86°W 85°W streets below BLVD. Here’s what would happen ... CAUSEWAY HAYNE BLVD. ¤i10 METAIRIE a W. ESPLANADE AVE. ROBERT E. LEE BLVD. THE BOWL LOYOLA DR. TRANSCONTINENTAL DR. Ÿu90

WILLIAMS BLVD. Much of the area is below FRANKLIN AVE. CHEF MENTEUR HWY. ¤i510 sea-level, creating a natural ¤i10 CLEARVIEW PKWY. VETERANS MEM. BLVD. Miss. River-Gulf Outlet “bowl.” Storm surge simply DAVID DR. 10 ELYSIAN FIELDS AVE. Intracoastal Waterway follows the law of gravity CLEARY ¤iAVE. Orleans AD CANAL BLVD. ¤i610 GENTILLY BLVD. and meanders to the E RO AIRI St. Bernard lowest points. ET ESPLANADE AVE. Ÿu61 AIRLINE DR. M b CITY BELOW THE SEA CANAL STREET ¤i10 JE EARHART EXPWY. pi River FF When a hurricane even stronger than Georges hits New Orleans, Lake Pontchartrain — a foot higher than sea sip ER W. JUDGE PEREZ DR. 310 sis S ARABI ¤i is O level — will be the city’s biggest threat. Surge water from the Gulf of Mexico, topped by towering waves, will M N H W swell the lake above levees and cause widespread flooding. A look at average surge levels by category, compared Y BROAD St. Charles . Jefferson to a cross-section of the city known as “the bowl”: CARROLLTON AVE.NEW ORLEANS c ST. BERNARD HWY. ALGIERS PARIS CHALMETTEROAD S AVE. HARAHAN T Hurricane Surge and waves . C H A M Category at low tide* Effect on New Orleans R G is LE EN si S A . D ss M VE. E G ip 1 7 feet Lake Pontchartrain’s levees stop the low-level surge AGA A pi ZINE UL Riv KEY: LE er GRETNA D 2 9 feet Levees stop the surge, but some waves could find their way over R 5 feet or more above sea-level AVONDALE . 3 14 feet Levees stop bulk of surge, but waves could cause considerable flooding PKWY. TERRY Ÿu90 WESTWEGO O r l e a n s 4TH 0 to 5 feet above sea-level 4 19 feet Levees topped, causing catastrophic flooding W J e f f e r s o n BELLE CHASSE HWY. ES Orleans 0 to -5 feet below sea-level T B BUS. Plaquemines 5 24 feet Entire city submerged including Mississippi River levees ANK LAPALCO BLVD. EXP -5 feet or less below sea-level WY. Ÿu90 HARVEY

Surge crashes inland a Lake Pontchartrain levee: with high wind-driven 14.5 feet above sea-level waves on top Approximate flooding b Cemeteries at c Mississi depth corresponds to City Park Ave.: 3.9 feet 21.4 fee satellite image above LAKEVIEW METAIRIE RIDGE MID-CITY FRENCH QUARTER 5 4 3 1 2 SEA-LEVEL CANAL STREET Lake Pontchartrain CANAL BLVD. Jewel Robert E. Lee Filmore Harrison Polk Base of Navarre Carrollton Jeff Davis Broad Galvez Claiborne Rampart Bourbon World Trade Normal lake level: ELEVATIONS Street: Boulevard: Avenue: Avenue: Street: I-610: Avenue: Avenue: Parkway: Street: Street: Avenue: Street: Street: Center: 13.4 fee 1 foot above sea level 0.9 feet -3.5 feet -4.9 feet -3.6 feet -4.6 feet -2.8 feet 1.9 feet -1.2 feet -1.8 feet -0.3 feet 0.6 feet 0.5 feet 2.3 feet 2.5 feet Note: Figures correspond to maximum surge heights, plus Lake Pontchartrain’s +1 sea-level. High tides could add as much as 2 feet, and the surge level could rise even higher in some spots on the lake’s shore. Elevations are approximate. Source: LSU’s Louisiana Water Resources Research Institute, Army Corps of Engineers, staff research