토지 침하: 미국 도시와 경제에 대한 위협

### 미국 도시를 위협하는 지반 침하: 원인, 영향 및 해결 방법
* 🏙 지반 침하는 미국의 많은 도시에 영향을 미치고 있으며, 일부 지역은 **연간 1cm씩 침하**되고 있습니다.
* 💰 이 현상은 해안 카운티에서 **매년 10조 달러의 상품과 서비스를 생산**하는 등 경제에 심각한 위협이 되고 있습니다.
* 🏗 공항, 철도, 항만과 같은 인프라가 위험에 처해 있으며 **주택 가치와 경제 활동에 잠재적인 영향을 미칠 수 있습니다.**
* 🌍 지하수 추출, 도시 개발 등 자연적 및 인위적 요인이 **지반 침하의 원인**이 됩니다.
* 🛠 완화 전략에는 **대수층 재충전, 물 사용량 줄이기, 기후 이동 고려** 등이 포함됩니다.
* 💧 관리형 대수층 재충전은 유망한 솔루션이지만, **연간 에이커 피트당 200~1,500달러의 비용**이 들 수 있습니다.
* 🌊 오렌지 카운티와 같은 성공적인 토지 침하 완화 사례는 **즉각적인 조치가 긍정적인 결과**를 가져올 수 있음을 보여줍니다.
* ⏳ 이 문제는 시급하지만, **미국 도시에 미치는 지반 침하와 그 영향을 해결할 시간**은 아직 남아 있습니다.

자연적 및 인적 요인으로 인해 발생하는 지반 침하는 미국의 도시, 인프라, 경제를 위협하지만 다양한 방법을 통해 완화할 수 있습니다.

The land below many major US cities is sinking. Regions of the Atlantic coast could be sinking by up to five millimeters annually. This phenomenon, known as land subsidence, where land is sinking, impacts the oil-rich Gulf Coast, the agricultural hub of California, and many other places across the US. Coastal counties produce $10 trillion in goods and services, employ 54.6 million people, and pay $4 trillion in wages, so about 2.8% of the US GDP is at risk. Whether it's the oil industry down south or all of our ports, which facilitate so much business and commerce in this region, we have to consider that this is something that's happening and happening in conjunction with other threats. Combine that with sea-level rise and the fact that almost 40% of the population resides in coastal counties, the US has an expensive and dangerous problem. From the perspective of a person standing on the land, it does not matter if the land goes

down or sea level goes up, and in many places land
subsidence rate is orders of magnitude faster than sea level rise. The value of the average Californian home experiencing
land subsidence has decreased by 6%. The good news is, unlike many climate hazards, this
one we can do something about right now. It's not cheap, and it's not easy, but we have tools in
our toolbox that can implement that and see the results in a short period
of time. I'm talking about months to years. Which US cities are sinking the fastest, and what does
that mean for the residents and the national economy? A majority of the US cities are affected by a certain
level of land subsidence. However, some of them experience some of the fastest
rates that they can imagine. For example, Port Arthur, New Orleans, and Biloxi
along the Gulf Coast of the United States experience rates as fast as one
centimeter per year, which is considered to be

extremely fast for a city and along the East Coast of
the United States. We have Chesapeake Bay, Hampton Road area, but also Charleston. They experienced some
of the fastest rates. And on the West coast of the United States, some of
the cities in California, such as Foster City, experienced some of the fastest rate of land
subsidence. This can be problematic for our infrastructure. A lot of the things that we built were built to be on
steady ground that doesn't shift. So if you think of something like a rail line and the
rail lines running across ground that's sinking, some of that will sink, some of it will not. So now you might have kind of erosion beneath the
track where you didn't have it before. You might have to realign the tracks, you might have
to regrade things. You might have to continually add land back where it's
sinking. High speed trains, a tiny land subsidence can be
deadly, but for some

infrastructures. Millimeter to centimeter of the land
subsidence probably would be okay. Majority of the infrastructure that are at risk
includes airports, but also linear infrastructure such as railways and pipelines. Ports and harbors are significantly affected, and also
highways. Land subsidence can also have an impact on home values. It could be that a buyer comes in and sees the obvious
cracks and all those things, and they are willing to pay less. But also, it could be that there is less
jobs because of all the overextraction and less economic activity. Or it could be that your private wells are going dry. Professor Nomad's research on the Central Valley of
California found that, on average, home values decreased by 8.1% if they were located in a high
subsidence area. He said he's confident extrapolating that data across
the US. There are a few reasons for land subsidence, some due
to human activities and others are natural.

One of the main reasons why land is sinking is completely out of our control, and it has to do with a rebound from the ice age when glaciers were on land. And as a result of removal of that giant mass, land is rising in Canada, for example. And in the perimeter of that land is falling, which includes, for example, East coast of the United States. The other natural driver of the land elevation change is tectonic processes. For example, earthquakes can make the land to rise, but also in some places to fall, so these two are considered to be natural processes. But we have a lot of processes that are made by human. The other reasons relate to how we've developed our cities. Land is being compacted because we're removing groundwater. We use groundwater to drink and for other purposes. And as we take water out from the land, the space beneath it becomes compact because we've built on top of it.

Another reason why land is sinking is because we put
very heavy things, like buildings, on land, and that's starting to compact as well. The infrastructure we've built on this unstable land is
at risk. The infrastructure that's at risk is also, in some
ways, the infrastructure that's causing the problem. Heavy buildings, heavy systems at ports, even rail. These are infrastructure that is weighing down the
land in some cases. It's also the infrastructure that's necessary to keep
a region thriving. And the thing you need to protect. And unfortunately, our airports are built on fill and
are sinking. So it's something that we have to really take
seriously knowing that airports and other critical infrastructure like hospitals and roadways are
sinking. Land subsidence can be mitigated fairly rapidly,
particularly those components that are related to human activities. Every location has a different experience with land
subsidence. There are four major categories for mitigating land
subsidence: one collecting water and putting it

back in the aquifer known as recharging, two: using
less water, three: borrowing water from a neighbor, and four: climate
migration. As aquifers are depleted, land subsides. If we recharge them, put water back under the ground,
aquifers would stop from subsiding or even rise. As a result of that, land subsidence can slow down or
completely stopped. This can be helpful for solving other climate issues
too. We can use the water that we have during, for example,
wet seasons through floods, collect that and treat that and inject that under the
ground and replenish our coffers and keep that water for the rainy days, in this case would be for
drought years. These kinds of projects can be some of the most
expensive. In California, for example, it costs somewhere between 200 and $50 per acre feet of
recharge to $1,500 per acre feet of each. So you see that huge.

And then the median was about, I think, $400 per acre
feet of recharge per year. So $400, that's on the median side. However, managed aquifer recharge is more affordable
than other above-ground reservoir solutions, which can cost between 2 to 5 times more. It has other benefits too. Managed aquifer recharge is not affected by surface
pollution. Water that is underground is not going to evaporate,
and water on the ground would purify itself. When it flows through the porous spaces, the
quality increases. He also suggests using less water or borrowing water
from a neighboring city or municipality, though that might be tricky in locations like the
west, where multiple communities rely on a limited water source like the Colorado River. Lastly, communities can consider climate migration
strategies where they move away from or stop building on land dealing with these issues. Local governments, local industries even need to take
this threat seriously and understand where the problems

are the greatest. I'm glad this research is coming to
light. Not like we need another problem, but it is another
problem that we face. And the more that we're aware of it, the more we can
do something about it. In United States, we have one very successful
groundwater management that comes together with land subsidence mitigation. So Orange County, very rapid land subsidence has been
observed there, which was tied to the groundwater extraction. So over the past decades, they began deliberately
recharging aquifers by using the surplus water that is provided either through rivers,
or rains, or floods. And as early as 2015, land subsidence has been almost
mitigated in the region. The bad news is we're sinking. The good news is we have time to do something about
it.

Which U.S. Cities Are Sinking And How Much It Will Cost To Stop Them?

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미국 주요 도시의 토지 가라앉기

지반 침하로 인해 미국 주요 도시 아래의 땅이 가라앉고 있으며, 캘리포니아의 농업 중심지인 걸프 연안과 미국 전역의 다른 지역에 영향을 미치고 있습니다.

이 현상은 수조 달러의 상품과 서비스를 생산하고 수백만 명의 사람들을 고용하는 해안 카운티를 중심으로 미국 GDP의 약 2.

8%에 위험을 초래하고 있습니다.

또한 침몰하는 땅으로 인해 캘리포니아 평균 주택의 가치가 6% 하락하고 있지만, 단기적으로 이 문제를 해결할 수 있는 해결책이 있습니다.

토지 침하: 인프라 및 부동산 가치에 미치는 영향

미국의 여러 도시, 특히 동부 및 서부 해안에서 지반 침하가 빠르게 일어나고 있어 철도, 공항, 고속도로와 같은 기반 시설에 심각한 위협이 되고 있습니다.

이 현상은 기반 시설에 영향을 미칠 뿐만 아니라 주택 가치 하락으로 이어져 침하가 심한 지역은 평균 8.

1%의 하락을 경험하고 있습니다.

지반 침하의 원인은 인간 활동과 자연적 요인 모두를 포함하여 다양하기 때문에 복잡하고 광범위한 문제입니다.

땅이 가라앉는 것은 빙하 반동이나 지각 활동과 같은 자연적인 과정의 영향을 받습니다.

지하수 채취와 무거운 인프라 건설과 같은 인간 활동도 지반 침하를 유발합니다.

이러한 현상으로 인해 공항, 병원, 도로와 같은 중요 인프라가 위험에 처해 있습니다.

특히 인간 활동으로 인한 지반 침하를 완화하는 것은 가능하며 지역에 따라 다릅니다.

대수층 관리 대수층 고갈 및 토지 침하에 대한 솔루션

대수층을 재충전하면 토지 침하 속도를 늦추거나 멈추게 하여 고갈에 대한 해결책을 제시할 수 있습니다.

관리형 대수층 재충전 프로젝트는 비용이 많이 들 수 있지만 지상 저수지보다 저렴하고 지표 오염의 영향을 받지 않는 등의 이점을 제공합니다.

재충전 외에도 물 사용량을 줄이고, 이웃으로부터 물을 빌리고, 기후 이동 전략을 고려하는 것도 대수층 고갈 문제를 해결하는 데 도움이 될 수 있습니다.

지하수 관리가 토지 침하에 미치는 영향

지하수 추출은 오렌지 카운티에서 급격한 지반 침하를 일으켰습니다.

2015년부터 잉여수를 이용한 의도적인 대수층 재충전은 이 지역의 토지 침하를 완화하는 데 도움이 되었습니다.

이 성공적인 지하수 관리 접근 방식은 토지 침하 문제를 해결할 수 있는 잠재적인 해결책을 제공합니다.