Isn't the sand used for building computers?
Hawaii’s Beaches Are Disappearing
31–34 of 34 posts
Re: Hawaii’s Beaches Are Disappearing
#32How is this issue affected by rising sea levels? I'd think that those beaches are doomed anyway and not even sea walls are going to save those houses.
The beach erosion is accelerated by the presence of walls [1]. In general the regulation of seaside buildings is extremely lax in the US, and this takes a toll on the beaches. As a counter-example, in Greece seaside houses must be built at least 30m inlands from the end of the beach. It is also illegal to cut-off public access to the beach. [1] http://www.beachapedia.org/Seawalls
The only cause-effect given in your linked article I saw was:
“Active Erosion - Refers to the interrelationship between wall and beach whereby due to wave reflection, wave scouring, ‘end effects’ and other coastal processes the wall may actually increase the rate of loss of beach. This is site-specific and dependent on sand input, wave climate and other local factors.”
I didn’t see any explanation in the article (however I couldn’t scroll past the map part way through the article because I was using a touch device - grrrrrr).
Re: Hawaii’s Beaches Are Disappearing
#33Earlier quoted context omitted.
The beach erosion is accelerated by the presence of walls [1]. In general the regulation of seaside buildings is extremely lax in the US, and this takes a toll on the beaches. As a counter-example, in Greece seaside houses must be built at least 30m inlands from the end of the beach. It is also illegal to cut-off public access to the beach. [1] http://www.beachapedia.org/Seawalls
The only cause-effect given in your linked article I saw was: “Active Erosion - Refers to the interrelationship between wall and beach whereby due to wave reflection, wave scouring, ‘end effects’ and other coastal processes the wall may actually increase the rate of loss of beach. This is site-specific and dependent on sand input, wave climate and other local factors.” I didn’t see any explanation in the article (how…
You've also missed passive erosion. Obviously, specific numbers can't be given because the effect varies with the specifics of each beach. But it's not really rocket science, at least if you have ever lived close to a beach.
To preserve a beach, you need the waves to leave behind as much solid material as possible. In an open beach, you can observe much of the wave being "absorbed" by the beach rather than "pulling back" in the sea. When the wave is "absorbed", any solids carried by the wave settle on the beach.
If you place a wall on the beach: (a) you prevent the waves from reaching further inlands where they have been attenuated so they can be "absorbed" and leave the solids they carry behind, (b) you force them to "pull back" while they still carry a lot of energy, which will also carry away some of the existing solid material on the beach.
Or, if you prefer a mathematical explanation, the waves shape the beach so that its vertical gradient is a continuous function. If you force a discontinuity (wall) in the gradient, the waves will shape the beach so that there is no discontinuity. I.e. either the wall will be destroyed, or the beach will erode and the waters will become deeper.
Re: Hawaii’s Beaches Are Disappearing
#34Earlier quoted context omitted.
I think the problem is that even if the houses are far back enough that they are 1m about sea level, they are now at extreme risk of destruction if there is a major weather event where they might have previously avoided it.
I don't think it is fair to say that they are now at an extreme risk of destruction. Risks always exist. The risk of flooding is probably some small percent higher than it was 10 years ago, and 10 years before that. The risk will increase over the next 100+ years until the homes are destroyed. It seems like a problem that will work itself out. Either insurance will go up, the house value will go down, or both.
In the mainland US, houses right on the shore that are likely subject to storm surge are covered by some kind of government program since private insurance won't touch them. I have forgotten the details, unfortunately.