Land Subsidence: A Glimpse of Change at Home

October 31, 2016
Claire Kim Seoul International School 12th Grade

Claire Kim Seoul International School 12th Grade

Blinded by the economic benefits made possible through rapid industrial expansion and modern technology, it is easy to neglect their unintended yet possibly catastrophic consequences on the environment. In fact, according to the United States Geological Survey (USGS), our current methods for obtaining freshwater from the ground may quickly deplete it as a natural resource while also causing long-term and irreversible damage to the surrounding land.

The USGS reports that groundwater is the source of drinking water for approximately 50 percent of the American population, while 50 billion gallons of it is allocated towards agricultural use. This rapid consumption is now causing it to be pumped from aquifers at a faster rate than it can be replaced which will inevitably result in their eventual depletion, since it is a fundamentally nonrenewable natural resource. This unsustainable rate of extraction is also causing land subsidence and ground contamination while drying up wells in several states, mainly those on the west coast.

In the US, the main causes of land subsidence include the compaction of aquifer systems, the oxidation of organic soils, and the collapse of cavities in carbonate rocks, which are vulnerable to both chemical and mechanical weathering.

Land subsidence itself can have several consequences, including infrastructure destruction and groundwater contamination. Even though it is seemingly harmless, land subsidence can decrease protection from extreme weather events, such as floods and hurricanes, not only increasing the potential cost of reconstruction, but also threatening human lives. According to an estimate by the National Research Council, the annual cost in the US from flooding exceeds $125 million. In addition to causing costly infrastructural damage, land subsidence can also lead to groundwater contamination, mainly in the form of saltwater intrusion. Louisiana, a state that loses nearly 25 square miles of land yearly, has lost entire freshwater ecosystems due to saltwater intrusion. The loss of freshwater trees leads to further land erosion, as the roots can no longer hold the land together, leading to a vicious feedback loop of ecosystem loss and land erosion.

In an effort to curb land subsidence, many states such as California have already taken measures to pressurize depressed aquifer systems and to strictly regulate the extraction of groundwater. The industrial and agricultural sector are being closely regulated in the amount of groundwater extraction while hydrologists search for alternative methods to obtain freshwater in a desert landscape.


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