NCEES Principles and Practice of Surveying Practice Exam

What phenomenon describes the sinking of land typically due to natural resource extraction?

1. Flooding

2. Subsidence

3. Liquefaction

4. Erosion

The correct answer is: Subsidence

The phenomenon that describes the sinking of land due to natural resource extraction is known as subsidence. This occurs when the ground surface drops as a result of the removal of resources such as water, oil, or minerals, which can result in the lowering of the weight supported by the underlying materials. As these materials are lost or become less stable, the ground may settle or sink, leading to various problems including structural damage to buildings and infrastructure. Subsidence can be particularly significant in areas where extensive pumping of groundwater occurs, as the void left by the extracted water causes the land above it to collapse. This is different from flooding, which involves the overflow of water onto normally dry land, and from erosion, which refers to the wearing away of soil and rock typically caused by wind or water movement. Liquefaction is a process that can occur during earthquakes, where saturated soil temporarily loses its strength and behaves like a liquid. Understanding subsidence is crucial in surveying and land management, particularly in urban areas where significant resources may be extracted and where the stability of the land is necessary for safety and construction.