#Including those same east coast grasses! As well as iceplant and other things | Explore Tumblr posts and blogs

screambirdscreaming · 7 months ago

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Beach sand dynamics are stupidly complicated. In some places, yes, native vegetation holds the sand together and stabilizes the dunes. In other places, invasive vegetation introduced to stabilize the dunes fucks up the cycles of where sand is eroded from and deposited, leading to dunes forming in places people don't want them even as beaches erode nearby. (Also, massive changes to the structure of coastal wetlands.)

Whether waves deposit sand on a beach, or erode it away, has to do with the beach slope, the sand particle size, the angle at which waves approach, the wavelength and amplitude of the waves..... A guest lecturer for my coastal engineering class told us that, when running computer models of erosion and deposition responses to proposed beach projects like this, you're lucky if you end up in the right order of magnitude.

Beaches are very dynamic. It's not uncommon for hundreds of tons of sand to shift on and off a beach over the course of a year, usually scoured off by winter storms and deposited back over the summer. Anything that tries to modify that process - such as to prevent the sand from scouring away past a certain point - runs the risk of massively changing the dynamics in unpredictable ways.

And then, with "beach nourishment" projects like this, there's the question of where the sand comes from - where it was mined, and what the environmental impacts of sand mining there are - as well as the question of where the sand ends up if it all erodes away like this. (Did you know there's a sand mafia? That's more to do with the mining of sand for concrete, though.)

Anyway the bottom line is: don't put your fucking house there.

You think you're "next to" the beach, but you're very much *on* the beach as far as the scope of its natural processes go. And either you're fucking those dynamics up, or they're going to fuck you up. Or both!

absolutely losing my mind that a bunch of nimby assholes spent $500k to build a sandcastle that was promptly wiped away

#My understanding is that on the east coast of north America many of the problems stem from loss of native beachgrass and plant communities #While on the west coast many of the problems stem from the introduction of invasive plant species to hold the dunes #Including those same east coast grasses! As well as iceplant and other things #Also seawalls. Those have been built all over and they're a stupid idea everywhere #I said these dynamics are complicated to model but for seawalls specifically its actually very easy #A seawall redirects wave force in such a way as to undermine its own footing. There's physically nothing else it can do.#Frankly one of the most concisely self-destructive ideas ever implemented #And we built a lot of them!#There's many other types of shoreline armoring or soft shoreline protection #From those giant concrete jacks to rock rubble to anchoring driftwood down with rebar #All of which have their own mess of possible effects #Some of which are much better ideas than others #But as a baseline - colonist land use has been incredibly obtuse about building permanent structures in dynamic environments #Like coasts. And river banks. And other places but *especially* coasts and rivers #Trying to pin down a landspace which exists in a dynamically stable state is going to backfire in so many huge messy ways #Dumping half a million dollars of sand into the ocean is frankly the least of it

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