Tuesday, January 21, 2014

The Disappearing of Louisiana, Part 2: Water Words


The Zen of Flowers and Refineries, by Raina Benoit. Lafayette, Louisiana. 


To get a handle on the disappearing of Louisiana, I need to educate myself on water words. Unless quoted by an attributed source, everything below is based on my (flawed) understanding of water terms. 

Wetlands

1.      "Wetlands" is the parent category for these subcategories:
  • Swamp
  • Marsh
(there are more, but I'm trying to keep it simple)

2.      Wetland
An area that is inundated or saturated by surface or groundwater at a frequency and duration to support ... a prevalence of vegetation typically adapted for life in saturated soil conditions
3.     Swamp
 a wetland that is forested ... Many swamps occur along large rivers where they are critically dependent upon natural water level fluctuations. Other swamps occur on the shores of large lakes. [I added the boldface for emphasis.]
4.     Marsh
A type of wetland that is dominated by herbaceous rather than woody plant species ...
Marshes can often be found at the edges of lakes and streams, where they form a transition between the aquatic and terrestrial ecosystems. They are often dominated by grasses, rushes or reeds


Wetlands are important because they: 
  • Help mitigate the effects of river flooding and hurricane-led coastal surges
  • Protect water quality by trapping contaminants on the wetlands floor
  • Protect shorelines from erosion




Cypress swamp, Natchez Trace, Mississippi.



Bayou

A bayou is a slow-moving creek or a swampy section of a river or a lake. They are usually found in flat areas where water collects in pools. Bayous are often associated with the southeastern part of the United States.

Bayous are usually shallow and sometimes heavily wooded. They can be freshwater, saltwater, or a combination of both. This combination is called "brackish water."
Source: National Geographic Education

The Bayou Teche may be south Louisiana's most prominent bayou. Thousands of years ago, it was the main channel (see below) of the Mississippi River. Bayou Teche is 125 miles long and feeds into the Atchafalya River.


Tributaries v. distributaries

  • A tributary is a freshwater stream that feeds into a larger stream or river
  • A distributary is a stream that branches off and flows apart from the mainstem of a stream or river. 
 Source: National Geographic Education

Another description Rivers are connected together in vast networks of tributaries, which feed water into the main river channel, and distributaries, which pull water out of the main channel.


Channel

The channel isn't the water; it is the container of the water - the bottom and sides of the river, for example. The banks of a river are part of the channel.

The above is a neutral definition of a channel. Some channels are man-made. Canals and ditches are man-made channels.

A man-made channel is a double-edged sword. It can control the passage of water and can prevent some floods. On the other hand, water moves through a man-made channel faster (thus stronger) than a natural channel. Consequently, when water does top the channel banks, it is a more dangerous flood because its force is stronger than it would have been in a natural channel. And if there are no wetlands to absorb the brunt of the flood, there is more erosion, more property damage, more loss of life.

A movie short

Below is a five-minute video by Kael Alford called Bottom of 'da Boot: Louisiana's Disappearing Coast:






Related posts

Disappearing Louisiana, Part 1: Stumbling on History
Disappearing Louisiana, Part 2: Water Words
Disappearing Louisiana, Part 3: Paradise Faded: The Fight for Louisiana
Disappearing Louisiana, Part 4: Revetments, Rip-rap, and Other Exotica
Disappearing Louisiana, Part 5: The Control of Nature: Atchafalaya

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