The Bonnet Carré Crevasse (1871) was one of several levee breaches in the Bonnet Carré area in the mid-to-late 19th century.
Bonnet Carré was approximately 50 kilometers from
.
The breach occurred when excess water from the
Mississippi River
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...
flowed over the east bank levee of Bonnet Carré.
The original levee was over 12 feet high, and the
Crevasse
A crevasse is a deep crack, that forms in a glacier or ice sheet that can be a few inches across to over 40 feet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pie ...
itself spanned about 1200 feet.
Local drainage systems were unable to contain the floodwater.
The water rushed at 8 miles per hour, causing the width of the breach to increase by the day.
Strong northerly winds caused the excess water entering
Lake Pontchartrain
Lake Pontchartrain ( ) is an estuary located in southeastern Louisiana in the United States. It covers an area of with an average depth of . Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about from wes ...
to flow into populated areas to the east, including neighborhoods
Metairie and
Gentilly.
The increasing force of the flood also caused another nearby levee to break.
Although the devastation to the Bonnet Carré area was great, its ecological impacts were somewhat beneficial.
By diverting river water and sediment, the crevasse saved a greater portion of land surrounding the area from succumbing to total flooding and land erosion.
Therefore, the crevasse served as a buffer for wetland erosion. Recognizing the benefits, the local government commissioned the construction of an
artificial crevasse that could be periodically opened to drain excess water from the Mississippi into Lake Pontchartrain.
The river levee was not restored at Bonnet Carré until 1883.
The area is now the site of the
Bonnet Carré Spillway.
References
{{DEFAULTSORT:Bonnet Carre Crevasse
1871 in Louisiana
Floods in Louisiana
19th century in New Orleans
1871 natural disasters in the United States