Water scarcity is among the most pressing environmental problems of the 21st century. Different agro-ecological zones globally are experiencing varying degrees of drought, ranging from partial to extreme, depending on location. In 2020, the expected estimate of global demand for water is 5.5 cubic kilometers. According to the source, agriculture water productivity will increase at the rate of 0.8% per annum and industrial use at around 0.5% a year.

There are different sources of freshwater worldwide, such as streams, lakes, rivers, and underground water.
Most farms, industries, and cities depend on underground supply to meet their daily requirement. According to new studies, one-third of the earth’s largest groundwater basins are under threat because humans are draining so much water from them. Of these, 21 have exceeded sustainability tipping points and are being depleted, with 13 considered significantly distressed, threatening regional water security and resilience.

The implication is that the world’s largest aquifers are “overstressed,” meaning that there is not enough water replenished to offset the usage.
Constant rising populations, expanding agriculture, and growing industrialization are further putting pressure on demand for water. By building dams, reservoirs, and digging wells, efforts have been made to collect H2O; some countries have also tried to recycle and desalinate (remove salts) water. Conservation has become the need of the day.

Following the increasing demand for water for daily use, groundwater recharging by harvesting rainwater is gaining importance in many cities around the world.
One of the forest’s ecological roles is intercepting rain and allowing it to seep gently into the ground as vegetation breaks the fall. This groundwater, in turn, feeds wells, lakes, and rivers. Protecting forests means protecting water ‘catchments’ and also further enhancing carbon sequestration and combating climate change.

Rainwater Harvesting
In modern-day development and human expansion of cities, the construction of houses, footpaths, and roads has left little exposed earth for water to soak in. In poorly planned towns, flood quickly flows to the rivers, which then dry up soon after the rains stop. It can seep into the ground and recharge the groundwater supply if this process is suspended.

In some cities, this has become a prevalent method of conserving H2O, especially in the areas with control policies. Rainwater harvesting essentially means collecting rainwater on the roofs of buildings and storing it underground for later use. Not only does this recharging arrest groundwater depletion, but it also raises the declining water table and can help augment water supply. Rainwater harvesting and artificial recharging are becoming critical issues. It is essential to stop the decline in groundwater levels, prevent sea-water from moving landward, and conserve surface H2O run-off during the rainy season.

We recommend that various governments adopt policies in making rainwater harvesting compulsory in all new structures. If a new building did not have provisions for rainwater harvesting, no H2O or sewage connection would be given. Such rules should also be implemented in all the other cities to ensure a rise in the groundwater.

Farmers can also be encouraged to construct natural H2O harvesting reservoirs from external catchments; this will help increase all year round farming as more H2O will be made available for irrigation during the dry season.

Some of the adverse effects of groundwater depletion include
• Land subsidence
• Increased pumping costs
• Deterioration of water quality
• Reduction in streams and lakes
• Drying up of wells

Practical Ways Of Reducing Water Demand
There are simple techniques that can be used to reduce the demand for H2O, both by man and nature. The underlying principle is that only part of the rainfall or irrigation water is taken up by plants or harvested and used by man. The rest percolates into the deep groundwater and flows into any nearby water body (streams, lakes, rivers) or is lost by evaporation from the surface. Therefore, by improving the efficiency of H2O use and reducing its loss, we can minimize H2O demand from underground reserves.

There are various tested methods applied in different agro-ecological zones to reduce such losses and to improve soil moisture. Some of them are listed below.
1) Mulching, i.e., the application of organic or inorganic material such as plant debris, compost, etc., slows down the surface run-off, improves the soil moisture, reduces evaporation losses, and improves soil fertility.
2) Soil covered by crops slows down run-off and minimizes evaporation losses. Hence, fields should not be left bare for long periods.
3) Plowing helps to move the soil around. As a consequence, it retains more water, thereby reducing evaporation.
4) Shelterbelts of trees and bushes along the edge of agricultural fields slow down the wind speed and reduce evaporation and erosion.
5) Planting of trees, grass, and shrubs breaks the force of rain and helps rainwater penetrate the soil.
6) Fog and dew contain substantial amounts of water that can be used directly by adapted plant species. Artificial surfaces such as netting-surfaced traps or polyethylene sheets can be exposed to fog and dew. The resulting water can be used for crops.
7) Contour farming is adopted in hilly areas and lowland areas for paddy fields. Farmers recognize the efficiency of contour-based systems for conserving soil and H2O.
Salt-resistant varieties of crops have also been recently developed. Because these grow in saline areas, overall agricultural productivity is increased without making additional demands on freshwater sources. Thus, this is an excellent water conservation strategy.
9) Transfer of H2O from surplus areas to deficit areas by inter-linking H2O systems through canals, etc.
10) Desalination technologies such as distillation, electro-dialysis, and reverse osmosis are available.
11) The use of efficient watering systems such as drip irrigation and sprinklers will reduce the H2O consumption by plants.
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