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Understanding New Orleans Hydrology and Soil Dynamics

Explore the intricate hydrology and soil composition of New Orleans, including historic maps, water table depth, soil types, and subsidence concerns. Learn how these factors impact urban development and flooding risks in the region.

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Understanding New Orleans Hydrology and Soil Dynamics

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  1. HYDROLOGY

  2. Source: map drawn my M.W. Brown

  3. Source: Taylors historic map of New Orleans

  4. London ave canal Orleans canal 17th canal Source: Times Picayune

  5. 1965 Proposed levee protection system Expected to take 10-15yrs to complete pre-katrina Now expected to be finished in 2015 Image from Times-Picayune

  6. Flooding from hurricane Betsy in 1965 Pontchartrain park was inundated pontilly Source: USACE 1965

  7. Source: FEMA

  8. Aquents, dredged Allemands Muck, drained Schriever Clay Cancienne Silt Loam Urban Land Soil Types Concerns associated with these types of soil: ~ Subsidence ~ Flooding ~ Depth to Saturation Zone ~ Shrink-Swell Source: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

  9. Soil Texture ~ Soil texture influences water-retention and water-transmission traits ~ Clay soils have the finest texture and the smallest sized particles (graded to less than 0.002mm) ~ Finest texture soils are often found in backswamp areas 53-75% Clay (finest) 37-52% Clay <30% Clay (coarsest) N/A Sources: Map - Campanella, Particle size - Christopherson

  10. Water Table Depth ~ The depth of the water table is important in determining the ability of soil to absorb surface waters ~ The water table affects the footing type of built structures (i.e. high water table = no basement) 0-2 feet below the surface 1-3 feet below the surface 1.5-4 feet below the surface N/A Source: Campanella

  11. Organic Content of Soil ~ Soil rich in organic matter is prevalent in frequently water saturated, low lying areas ~ In the presence of oxygen bacteria decompose this organic material, which can lead to considerable subsidence >55% Organic Matter 2-13% Organic Matter N/A Source: Campanella

  12. Subsidence Causes of shrinking (sinking) soil: ~ draining water leads to decomposition of organic matter ~ consolidation of particles, a non-reversible process ~ surface load -10 to -29mm -8 to -9.9mm -6.3-7.9mm -5.5 to -6.29mm -5.1 to – 5.49mm -4.7 to -5 -4 to -4.69 -3.1 to -3.9 -1.8 to -3 -1.79 to 10.3 mm Source: Adapted from Dixon

  13. Source ListCampanella, Richard. 2006. Geographies of New Orleans: Urban Fabrics Before the Storm.Christopherson, Robert. 2006. Geosystems: an Introduction to Physical Geography. Dixon, Timothy H. Nature, vol 441, pps 587-588, 1 June 2006. U.S. Department of Agriculture Natural Resource Conservation Service Web Soil Surveyhttp://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

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