Environment Louisiana Coastline in 2100

Discussion in 'Free Speech Alley' started by Bengal B, Aug 30, 2014.

  1. Bengal B

    Bengal B Founding Member

    Joined:
    Sep 5, 2002
    Messages:
    13,564
    Likes Received:
    2,133
  2. red55

    red55 curmudgeon Staff Member

    Joined:
    Oct 21, 2002
    Messages:
    40,537
    Likes Received:
    6,240
    That map is inaccurate. It assumes effective sea-level rise as a worst possible case. In fact, deltaic subsidence is variable and in some places the water won't go so high. Worse the map does not take marine processes into account. Once the protecting marshlands are gone, those thin levee ridges sticking out into the ocean cannot long exist in the face of wind and wave action. They will be reworked into headlands and barrier islands.
     
  3. Winston1

    Winston1 Senior Member

    Joined:
    Sep 5, 2010
    Messages:
    2,891
    Likes Received:
    1,268
    It also doesn't seem to take into account the land building by the Atchafalaya river. It's delta is growing.

    Regardless the current efforts are much too little. The levee system as it is presently constituted is the main culprit....the sediment that could help begin to rebuild the coast is being dumped into the deep water at the mouth. There should be serious diversion of the Mississippi below New Orleans to begin coastal restoration.
     
    red55 likes this.
  4. red55

    red55 curmudgeon Staff Member

    Joined:
    Oct 21, 2002
    Messages:
    40,537
    Likes Received:
    6,240
    It was growing. But since the completion of the 5 unnecessary dams on the Red River by, who else, the Corps of Engineers, most of the sediment reaching the Atchafalaya is being caught behind the dams, which deprive the Atchafalaya delta of sediment. It is also filling up the pools in the Red River rapidly, causing the Corps to have a permanent job dredging them. The Mississippi historically provided less than 20% of the sediment in the Atchafalaya despite providing 80% of its water. I hate the Corps of Engineers. I'll take their research money, but I hate them.

    Well, this is another highly touted feel-good project that will not work to rebuild the delta. It will nourish a few acres of marsh in the immediate vicinity of the diversion structures and that is about it. The problem is that there is too little sediment to be diverted. All of the dams on the upper Mississippi, Ohio, and especially the sediment-rich Missouri River have caught the lions share of the sediment that once nourished the delta. Practically no sand and gravel can be diverted by these projects which only allow fine suspended clays to run out through over bank levee diversions. The heavy delta-building sediment sliding along in the bed load at the bottom of the channel does not get diverted. It goes straight out the birdfoot and gets dumped in deep water off the continental shelf.

    Politicians want to spend a Trillion dollars "restoring" a delta that cannot be restored and trying to keep the Mississippi River from changing courses at Old River. Which, of course, is the solution to the delta problem! Let the River find a new course to the sea and build a new delta in shallow waters like it is supposed to. Scientists realize that Deltas are ephemeral and always have been. They have a lifetime and then are abandoned by the river and a new delta is built. But we will waste billion trying to solve the wrong problems for the wrong reasons.

    And the damned engineers in their obsession to "control" rivers and prevent flooding have caused all of the problems that we have by leveeing the river into single channels and damning all of its distributaries and robbing it of sediment. People need to understand that a river is not just the channel, it is the channel and its floodplain. That floodplain must be respected and allowed to function naturally if we expect rivers and deltas to remain healthy.

    I hate the Corps.
     
    Tiger in NC and Winston1 like this.
  5. Winston1

    Winston1 Senior Member

    Joined:
    Sep 5, 2010
    Messages:
    2,891
    Likes Received:
    1,268
    Well said Red!
     

Share This Page