Engineering geology of New Orleans
Among those who can look beyond the ubiquitous concerns of the “energy crisis,” there is a consensus that the decade of the 1980’s will witness recognition of widespread regional water shortages as perhaps the next national “crisis.” How quickly people tend to forget or ignore the water rationing episodes in several of America’s larger cities only several years ago! But the City of New Orleans and its suburbs belong in a small category of major cities in which water in overabundance is the nemesis rather than a scarce natural resource. In fact, it is no overstatement to say that the single greatest regional engineering concern is literally to keep the city from drowning. Coupling this regional concern, with the project-specific one of unusually weak foundation conditions, sets the stage for this overview of the engineering geology of the Crescent City-the location of the French Quarter, the Mardi Gras, and Canal Street (Figure 1).
In an article more than a decade ago by the junior author (Saucier, 1965), the setting of New Orleans was described as being the flattest, lowest, and geologically youngest of any major city in the United States. Quantification of this reveals a maximum relief of about 7 m within an area of 385 km2, an average elevation of about 0.4 m above mean Gulf level (Schultz and Kolb, 1954, Fig. 2), and no surficial deposits older than 2,500 years (Saucier, 1963). Elaboration on the elevation statistic reveals that over 45 percent of the urbanized area of the