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Development of the New Orleans flood protection system prior to Hurricane Katrina / J. D. Rogers in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°5 (Mai 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 602–617 Titre : Development of the New Orleans flood protection system prior to Hurricane Katrina Type de document : texte imprimé Auteurs : J. D. Rogers, Auteur Année de publication : 2008 Article en page(s) : pp. 602–617 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Louisiana  Hurricanes  Floods  Canals Résumé : The system of flood protection surrounding New Orleans and its adjoining parishes prior to Hurricane Katrina evolved over a period of 280years . The earliest drainage works sought to elevate the river’s natural levees and excavate drainage canals leading towards Bayou St. John, the only natural break across the Metairie-Gentilly distributary ridge. An extensive zone of Cypress Swamps occupied the levee flank depression between the ridge and Lake Pontchartrain. 58km of drainage canals were excavated across the natural levee backslope and through the swamp depressions bordering the lake between 1833 and 1878. These canals sought to drain the lower portions of the city, which suffered periodic outbreaks of yellow fever, which killed more than 100,000 people during the 19th century. The city has not suffered flooding from the Mississippi River since 1895, most damaging floods having emanated from hurricane surge off of Lake Pontchartrain. Since 1559, 177 hurricanes have struck the Louisiana coastline. A system of pump stations was constructed between 1895 and 1927, which pump water into the river, the lake, and adjacent bayous. The cypress swamps were replaced by the Lakeview and Gentilly residential districts, built after 1945. This old swamp zone has settled as much as 3+m since 1895. After 1927 the Army Corps of Engineers assumed a leadership role in providing flood control infrastructure, supervising the Mississippi River & Tributaries Project in 1931–1972. In 1955 the Corps role was expanded to include the City of New Orleans, which included maintaining capacity and freeboard of the old drainage canals. After a series of lawsuits between 1961 and 1977, the Corps was forced to employ concrete flood walls along the subsiding drainage canals. These walls were constructed in the 1990s, though some transition elements remained incomplete when Hurricane Katrina struck in August 2005. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2860 [...] [article] Development of the New Orleans flood protection system prior to Hurricane Katrina [texte imprimé] / J. D. Rogers, Auteur . - 2008 . - pp. 602–617. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 602–617 Mots-clés : Louisiana  Hurricanes  Floods  Canals Résumé : The system of flood protection surrounding New Orleans and its adjoining parishes prior to Hurricane Katrina evolved over a period of 280years . The earliest drainage works sought to elevate the river’s natural levees and excavate drainage canals leading towards Bayou St. John, the only natural break across the Metairie-Gentilly distributary ridge. An extensive zone of Cypress Swamps occupied the levee flank depression between the ridge and Lake Pontchartrain. 58km of drainage canals were excavated across the natural levee backslope and through the swamp depressions bordering the lake between 1833 and 1878. These canals sought to drain the lower portions of the city, which suffered periodic outbreaks of yellow fever, which killed more than 100,000 people during the 19th century. The city has not suffered flooding from the Mississippi River since 1895, most damaging floods having emanated from hurricane surge off of Lake Pontchartrain. Since 1559, 177 hurricanes have struck the Louisiana coastline. A system of pump stations was constructed between 1895 and 1927, which pump water into the river, the lake, and adjacent bayous. The cypress swamps were replaced by the Lakeview and Gentilly residential districts, built after 1945. This old swamp zone has settled as much as 3+m since 1895. After 1927 the Army Corps of Engineers assumed a leadership role in providing flood control infrastructure, supervising the Mississippi River & Tributaries Project in 1931–1972. In 1955 the Corps role was expanded to include the City of New Orleans, which included maintaining capacity and freeboard of the old drainage canals. After a series of lawsuits between 1961 and 1977, the Corps was forced to employ concrete flood walls along the subsiding drainage canals. These walls were constructed in the 1990s, though some transition elements remained incomplete when Hurricane Katrina struck in August 2005. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2860 [...]

Geologic conditions underlying the 2005 17th street canal levee failure in New Orleans / J. D. Rogers in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°5 (Mai 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 583–601 Titre : Geologic conditions underlying the 2005 17th street canal levee failure in New Orleans Type de document : texte imprimé Auteurs : J. D. Rogers, Auteur ; G. P. Boutwell, Auteur ; D. W. Schmitz, Auteur Année de publication : 2008 Article en page(s) : pp. 583–601 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Levees  Failures  Swamps  Marshes  Hurricanes  Louisiana Résumé : A careful program of subsurface sampling and cone penetration test soundings was employed to characterize the geologic conditions beneath the failed portion of the 17th Street Canal levee in New Orleans, where a 150m long section of the levee and floodwall translated up to ∼16m when flood waters rose to 1–2m of the wall’s crest on August 29, 2005, during Hurricane Katrina. The subsurface conditions are characterized by discrete layers of fill placed upon the historic cypress swamp, which is underlain by a deeper, prehistoric cypress swamp. These swamp deposits were consolidated beneath the levee, and in the area of the 2005 failure, the swamp materials infilled a natural depression believed to be an old slough, which dipped below the sheetpile tips for a distance of about 50m , which corresponds to where the breach appears to have initiated. Detailed examination of the recovered soils suggest that recent hurricanes periodically inundated the swamps with saline and/or brackish water, which cause a mass dieoff of swamp vegetation and flocculation of suspended clays, due to the sudden increase in salinity. These conditions promote deposition of discontinuous clay seams beneath layers of organics, which are then covered by fresh water swamp deposits. This sequence is repeated, like a series of tree rings, throughout the swamp deposits. The cypress swamp deposits lying beneath the levee also exhibit high hydraulic conductivity. These materials contain corky wood, and recovered samples often exhibited densities less than water. Nine of the post-Katrina borings recovered intact samples of a basal rupture surface comprised of organic silty clay exhibited near zero residual shear strength after shearing 80 to 100 mm. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2858 [...] [article] Geologic conditions underlying the 2005 17th street canal levee failure in New Orleans [texte imprimé] / J. D. Rogers, Auteur ; G. P. Boutwell, Auteur ; D. W. Schmitz, Auteur . - 2008 . - pp. 583–601. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 583–601 Mots-clés : Levees  Failures  Swamps  Marshes  Hurricanes  Louisiana Résumé : A careful program of subsurface sampling and cone penetration test soundings was employed to characterize the geologic conditions beneath the failed portion of the 17th Street Canal levee in New Orleans, where a 150m long section of the levee and floodwall translated up to ∼16m when flood waters rose to 1–2m of the wall’s crest on August 29, 2005, during Hurricane Katrina. The subsurface conditions are characterized by discrete layers of fill placed upon the historic cypress swamp, which is underlain by a deeper, prehistoric cypress swamp. These swamp deposits were consolidated beneath the levee, and in the area of the 2005 failure, the swamp materials infilled a natural depression believed to be an old slough, which dipped below the sheetpile tips for a distance of about 50m , which corresponds to where the breach appears to have initiated. Detailed examination of the recovered soils suggest that recent hurricanes periodically inundated the swamps with saline and/or brackish water, which cause a mass dieoff of swamp vegetation and flocculation of suspended clays, due to the sudden increase in salinity. These conditions promote deposition of discontinuous clay seams beneath layers of organics, which are then covered by fresh water swamp deposits. This sequence is repeated, like a series of tree rings, throughout the swamp deposits. The cypress swamp deposits lying beneath the levee also exhibit high hydraulic conductivity. These materials contain corky wood, and recovered samples often exhibited densities less than water. Nine of the post-Katrina borings recovered intact samples of a basal rupture surface comprised of organic silty clay exhibited near zero residual shear strength after shearing 80 to 100 mm. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2858 [...]