Final answer:
Subsidence is the term used to describe the lowering of ground surface elevation caused by effects such as overpumping of groundwater. Overpumping can lead to saltwater intrusion, pollution risks, and structural land issues like sinkholes.
Step-by-step explanation:
The dropping of the ground surface elevation due to the effects of overpumping is called subsidence. Subsidence is the downward motion of the land surface, and can be attributed to factors such as soil compaction, extraction of mineral resources, and significant withdrawal of groundwater. When groundwater is pumped in large amounts over a period, this can lower regional water tables—sometimes termed groundwater mining.
Groundwater and runoff are significant parts of the water cycle. Runoff refers to water from precipitation that flows over the land's surface and eventually collects in bodies of water, while groundwater is the water that soaks into the ground, possibly recharging aquifers that can store water for extended periods.