三河マルシェ【MARCHE】三河エリアのコミュニティポータルサイト

What exactly was beginning to come about was anthropogenic soil subsidence—the sinking in the land by human activity. When runoff is eradicated and artificial levees keep the river from overtopping, this groundwater lowers, the soils normally dry out, and the organic subject decays. All this creates air pockets inside the soil body, into which in turn those sand, silt, plus clay particles settle, consolidate—and decline below sea level.

 

Construction with the new drainage system initiated in 1896 and accelerated in 1899, when voters overwhelmingly authorized a two-mill property tax to set-up the New Orleans Sewerage and Water Board. By 1905, 40 miles of canal were excavated, hundreds of miles of pipelines and drains ended up laid, and six pumping stations were draining as long as 5, 000 cubic feet of water per second. System efficacy improved drastically after 1913, when a young engineer named Albert Baldwin Wood designed a large impeller pump that could possibly discharge water even more rapidly. Eleven “Wood screw pumps” were installed by 1915, many are still in work with today. By 1926, through 30, 000 acres of land were being “reclaimed” via 560 kilometers of pipes and canals which includes a capacity of 13, 000 cubic foot of water per next. New Orleans had eventually conquered its backswamp.

 

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