How to Calculate Surface Subsidence

Subsidence is an event that occurs when the ground for an area drops in height or elevation. The phenomenon is caused as the direct result of the withdrawal of groundwater. This water is stored in massive underground reservoirs known as an aquifer. As water is being pumped from the ground, the weight of the soil forces the land surface to sink. The sinking of the land is referred to as subsidence and needs to be monitored over time.

Things You'll Need

• Survey equipment

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Instructions

1. • 1

     Obtain a survey for a specific point or location. Make a note of the elevation of the land, the latitude and longitude.

   • 2

     Survey and note the land elevation, the latitude and longitude of another point or location. Make a note for any other points or locations.

   • 3

     Go back and resurvey the points or locations over the course of five to 10 years. Compare the updated surveys with the original surveys to determine how much subsidence has occurred.