Depletion of groundwater due to excessive withdrawal can have which of the following consequences? 1. Increased costs of groundwater irrigation. 2. Land subsidence. 3. Saltwater intrusion in coastal areas. 4. Environmental degradation of nearby Ecotones.
As the water table lowers, the water must be pumped farther to reach the surface, using more energy. In extreme cases, using such a well can be cost-prohibitive. So, statement 1 is correct. Land subsidence occurs when there is a loss of support below the ground. This is most often caused by human activities, mainly from the overuse of groundwater, when the soil collapses, compacts, and drops. So, statement 2 is correct. Saltwater intrusion is the movement of saline water into freshwater aquifers. The movement happens because saltwater has a higher mineral content than freshwater, it is denser and has higher water pressure. As a result, saltwater can push inland beneath the freshwater, which can lead to contamination of drinking water sources and other consequences. So, statement 3 is correct. An ecotone is a transition area between two biomes. It is where two communities meet and integrate. Groundwater feeds soil moisture through percolation, and many terrestrial vegetation communities depend directly on either groundwater or the percolated soil moisture above the aquifer for atleast part of each year. Hyporheic zones (the mixing zone of stream water and groundwater) and riparian zones are examples of ecotones largely or totally dependent on groundwater. So, statement 4 is correct.