5 ms·

> In Vermilion Parish, the shoreline is eroding between 3.3 and 23 feet per year What does this mean, how can a shoreline erode

Brybry 23d ago
Grade school level Louisiana info (probably somewhat wrong): It's generally brackish marsh/swamp land. Basically think silt/dirt with a bunch of plants evolved for this specific environment. Then you take a bunch of humans and you cut down all the really old cypress trees for lumber. To facilitate that process you cut channels through all the plants that are in the way so you can ship that lumber via new unobstructed waterways. You also do it for oil/gas exploitation. So now you have a lot of infiltration of saltier or fresher water and less protection during storm surge and such. Lots of plants die and these plants were holding the dirt/soil in place (and the storm surge helps wash that away). Also you re-engineer the original waterways that deposited silt/dirt and helped build these areas up so that they deposit silt/dirt in other places (also you harvest the silt/dirt for use in farming so it never even gets that far down the waterways in the first place).
- edg5000 23d ago
  In the Netherlands we rely on beach grass, a type of grass that can root well in loose sand, to keep dunes together. This forms the main sea barrier. The grass has historically been replanted at least partially to maintain the protection. This spans back at least a few hundred years I believe. It's interesting that Lousisana works so differently. I always kind of assumed that dunes would always be needed to keep the sea out in low lying areas, but that's not the case at all.
  - hadlock 23d ago
    Most of the erosion is due to oil and gas companies dredging poorly thought out canals to move drilling equipment through the marsh, causing unslowed erosion for ~70+ years.
hadlock 23d ago
The oil and gas companies brought in huge massive drilling rigs in the 1930s-1960s. The marsh was too soft/soggy to bring in the equipment overland, so they just... dredged huge canals in the soggy marsh a couple feet deep. You can see this in the opening shot of the video with the boat in the narrow canal. Labor was cheap and they were making a ton of money. They would put the dredged mud on one side of the channel, at random, causing random tracts to flood and most of the plants died, and then the marshes slowly sank below the water. One EPA report says for every acre of dredging they did (and they did a LOT) cause 3 more additional acres of erosion. If you go zoom in on the area where they're building, there are big squares and rectangles of dredging material, surrounding what look like square lakes. The state has been trying to get the oil and gas companies to restore the land but not much luck. Part of this deal with SpaceX (allegedly) is to restore the land and close off the canals to prevent further erosion.

Brybry 23d ago

Grade school level Louisiana info (probably somewhat wrong): It's generally brackish marsh/swamp land. Basically think silt/dirt with a bunch of plants evolved for this specific environment. Then you take a bunch of humans and you cut down all the really old cypress trees for lumber. To facilitate that process you cut channels through all the plants that are in the way so you can ship that lumber via new unobstructed waterways. You also do it for oil/gas exploitation. So now you have a lot of infiltration of saltier or fresher water and less protection during storm surge and such. Lots of plants die and these plants were holding the dirt/soil in place (and the storm surge helps wash that away). Also you re-engineer the original waterways that deposited silt/dirt and helped build these areas up so that they deposit silt/dirt in other places (also you harvest the silt/dirt for use in farming so it never even gets that far down the waterways in the first place).

edg5000 23d ago
In the Netherlands we rely on beach grass, a type of grass that can root well in loose sand, to keep dunes together. This forms the main sea barrier. The grass has historically been replanted at least partially to maintain the protection. This spans back at least a few hundred years I believe. It's interesting that Lousisana works so differently. I always kind of assumed that dunes would always be needed to keep the sea out in low lying areas, but that's not the case at all.
- hadlock 23d ago
  Most of the erosion is due to oil and gas companies dredging poorly thought out canals to move drilling equipment through the marsh, causing unslowed erosion for ~70+ years.

hadlock 23d ago

The oil and gas companies brought in huge massive drilling rigs in the 1930s-1960s. The marsh was too soft/soggy to bring in the equipment overland, so they just... dredged huge canals in the soggy marsh a couple feet deep. You can see this in the opening shot of the video with the boat in the narrow canal. Labor was cheap and they were making a ton of money. They would put the dredged mud on one side of the channel, at random, causing random tracts to flood and most of the plants died, and then the marshes slowly sank below the water. One EPA report says for every acre of dredging they did (and they did a LOT) cause 3 more additional acres of erosion. If you go zoom in on the area where they're building, there are big squares and rectangles of dredging material, surrounding what look like square lakes. The state has been trying to get the oil and gas companies to restore the land but not much luck. Part of this deal with SpaceX (allegedly) is to restore the land and close off the canals to prevent further erosion.