Groundwater is a natural resource of freshwater that soaks in the soil and stores in porous rocks and in other particles of the soil. It is also referred to as subsurface water to distinguish it from surface water. Groundwater accounts for nearly 95% of the freshwater resources. It can stay underground for hundreds of thousands of years, or it can come to the surface and help fill rivers, streams, lakes, ponds, and wetlands. Groundwater comes out of a spring or is pumped from a well. Both of these are common ways we get groundwater to drink. About 50 percent of our municipal, domestic, and agricultural water supply is groundwater. Groundwater composition depends on the kinds of soil and rocks the water has encountered in its movement through the subsurface.
How does water circulate?
Human activities and Groundwater contamination:
The general nature of the water cycle has various stages. Both surface and Groundwater are a part of the hydrological cycle. There is constant movement of water from above, on and below the earth’s surface. The cycle has no end or beginning but it is traced from the precipitation. Precipitation may occur in the form of rain, snow and hail, wets the ground. As there is more precipitation, it filters through the ground. The rate of percolation depends on the type of soil, land use and intensity of rain. Water infiltrates fastly through sandy soil than clay or silt. Almost no water filtrates through paved areas. Rainwater that cannot be absorbed flows as runoff.
When the soil cannot absorb anymore water it slowly moves to unsaturated surfaces by recharging the groundwater. The remaining runoff water moves towards rivers and eventually reaches the oceans. Water from surfaces that are not absorbed is evaporated. Oceans are the largest contributors to evaporation of surface waters. Evaporation and transpiration from plants rises above the earth’s surface, condenses and forms clouds. And then precipitation occurs.
Groundwater is highly susceptible to contamination of the human activities and the chemicals on the surface. Pesticides like nitrogen and phosphorus applied to soil as fertilizers may leak into the soil when there is irrigation and precipitation leading to increased contamination of water. Industrial waste, mine refuse, radioactive wastes, household materials and other anthropogenic sources dissolved into water are detected in Groundwater.
Is it hard to clean Groundwater?
Groundwater systems are complicated and the contaminants are dissolved so it takes longer time to clean.This makes it more difficult to design and build a suitable treatment plant that pumps the water to the surface and cleans the water.
How to increase Groundwater?
We must be looking at conserving Groundwater.Today, we are not able to recharge Groundwater at the same rate as we pump out. Planting and protecting trees will help in groundwater recharge. Using injection and recharge injection wells alongside river sand and feeder channels will recharge the ground aquifers and increase the water table.
Lakes of India 