Overexploitation of groundwater and intensive irrigation in major canal commands has posed serious problems for groundwater managers in India. Depletion of water tables, saltwater encroachment, drying of aquifers, groundwater pollution, water logging and salinity, etc. are major consequences of overexploitation. Declining groundwater at a rate of 1 meter over the years has been reported that in many parts of the country. Deterioration in groundwater quality by various causes is another serious issue. Increased arsenic content in shallow aquifers of West Bengal reported recently has created panic among the groundwater users. Summed together, all these issues are expected to reduce the fresh water availability for irrigation, domestic and industrial uses. If this trend continues unchecked, India is going to face a major water crisis in the near future. Pumping groundwater at a faster rate than it can be recharged will have negative effects on the environment and the people who needs water for livelihood. Here are eight impacts of depletion of groundwater.
- Depletion explores deeper zones of Earth.
The more we extract groundwater right below the Earth’s surface, the further down we have to go in order to get more. As we have to extract water from deeper within the Earth, we find that there is less water available. Consequently, we will have to use even more resources to develop alternative methods to reach further into the ground.
- Saltwater contamination.
We may pump groundwater instead of sourcing it from lakes and rivers, but that doesn’t mean that it isn’t connected to larger bodies of water. Groundwater that is deep within the ground often intermingles with saltwater that we shouldn’t drink. When freshwater mixes with saltwater, it is called saltwater contamination. This sort of contamination would raise the prices of drinking water for everyone because it will cost much more to pump and filter.
- Shortage of food supply
The depletion of aquifer would result in more stress to water availability. More than 80 % of our agriculture depends on groundwater reserves. Depletion will affect all the crops that would result in massive shortage in food, that would lead to suffering of millions of humans across the globe.
- Lowering of the water table
The most severe consequence of excessive groundwater pumping is that the water table, below which the ground is saturated with water, can be lowered. For water to be withdrawn from the ground, water must be pumped from a well that reaches below the water table. If groundwater levels decline too far, then the well owner might have to deepen the well, drill a new well, or, at least, attempt to lower the pump. Also, as water levels decline, the rate of water the well can yield may decline.
- Drying of Streams and Lakes
There is more of an interaction between the water in lakes and rivers and groundwater than most people think. Some, and often a great deal, of the water flowing in rivers comes from seepage of groundwater into the streambed. Groundwater contributes to streams in most physiographic and climatic settings. The proportion of stream water that comes from groundwater inflow varies according to a region’s geography, geology, and climate.
Groundwater pumping can alter how water moves between an aquifer and a stream, lake, or wetland by either intercepting groundwater flow that discharges into the surface-water body under natural conditions, or by increasing the rate of water movement from the surface-water body into an aquifer. A related effect of groundwater pumping is the lowering of groundwater levels below the depth that streamside or wetland vegetation needs to survive. The overall effect is a loss of riparian vegetation and wildlife habitat.
- Land Subsidence
The basic cause of land subsidence is a loss of support below ground. In other words, sometimes when water is taken out of the soil, the soil collapses, compacts, and drops. This depends on a number of factors, such as the type of soil and rock below the surface. Land subsidence is most often caused by human activities, mainly from the removal of subsurface water.
- Increase in cost of water
As the depth to water increases, the water must be lifted higher to reach the land surface. Larger capacity of pumps are used to lift the water (as opposed to artesian wells or dug wells or lower depth bore holes), much more energy is required to drive the pump. This can become prohibitively expensive over a period.
- Deterioration of Water quality
One water-quality threat to fresh groundwater supplies is contamination from saltwater intrusion. All of the water in the ground is not fresh water; much of the very deep groundwater and water below oceans is saline. In fact, an estimated 12.9 cubic kilometers of saline groundwater exists compared to about 10.5 million cubic kilometres of fresh groundwater (Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp. 817-823). Under natural conditions the boundary between the freshwater and saltwater tends to be relatively stable, but pumping can cause saltwater to migrate inland and upward, resulting in saltwater contamination of the water supply.
A step towards protecting our Ground water source
Rainwater harvesting for domestic use and depositing in our bore holes is becoming increasingly necessary as the availability of good quality groundwater declines. Rainwater is acknowledged as a sustainable source of water that protects us and the ground water.
Households and communities have no option but to substitute their groundwater with rainwater for reasons of Scarcity, Salinity, Superior quality and Risk. Rainwater enhances water security in the house and provides a good quality water. Rainwater may be the sole source of water in countries like the Maldives and upland Sri Lanka, provide an alternative to arsenic-laden ground water in Bangladesh and augment inadequate urban supplies from Chennai to Kathmandu and scattered households in the mountain ridges in Bhutan. Rainwater use is nowadays promoted by Governments and NGOs alike for numerous domestic applications like drinking, cooking, bathing, laundry, toilet flushing and for gardening purposes. Infiltration to sustain local aquifers is suggested as well.
“Let’s leave legacy of water for our generations to come”
Vardhman Envirotech,
India’s Passionate Rainwater Company.