Ground Water and Sea Level
By Dr Arvind Kumar
Groundwater is used for many purposes. Massive extraction of groundwater for crop irrigation, drinking water or industrial purposes may result in an annual rise in sea levels of approximately 0.8 mm, accounting for about one-quarter of total annual sea-level rise (3.1 mm). The findings from a recent research study by hydrologists from Utrecht University and the research institute Deltares show that the rise in sea levels can be attributed to the fact that most of the groundwater extracted ultimately winds up in the sea. It is further observed that alternately severe ground water extraction near the sea will also tend to have the sea water replace the ground water table. Currently, sea levels around the world are rising. Present sea level rise potentially impacts human populations (e.g., those living in coastal regions and on islands) and the natural environment (e.g., marine ecosystems). Global average sea level rose at an average rate of around 1.7 ± 0.3 mm per year over 1950 to 2009 and at a satellite-measured average rate of about 3.3 ± 0.4 mm per year from 1993 to 2009.According to these findings, two main factors are known to contribute to observed sea level rise. The first is thermal expansion: as ocean water warms, it expands. The second is from the contribution of land-based ice due to increased melting. The major store of water on land is found in glaciers and ice sheets. Now there may be a third reason: ground water extraction. It is further revealed that depletion is the most acute in areas of India, Pakistan, the US and China, which are also the regions without sustainable levels of food production and water consumption and which are expected to experience major problems in the long run.
