WATER AND ITS USES
Water is an indispensable natural resource. About 97% of the earth’s surface is covered by water. Water is essential for maintenance of life.  It is necessary to sustain life on Earth.
Distribution of Water on Earth
- 4% of the whole Earth is water.
- 6% is freshwater
- 98 % is in ice caps and glacier form
- Only 0.007% is present in form of Lake, 0.005% as soil moisture, 0.001% as atmospheric moisture, and 0.0001% as rivers.
Importance
- Every organism in the world needs water for survival.
- Human beings need water for drinking, bathing, cooking, washing clothes, etc.
- Water is required for photosynthesis.
- Animals too need water for survival.
- During the summer seasons, the quantity of water consumption increases.
- Water in form of snow, precipitation, ice caps, and glacier maintain ecological equilibrium and thus persistent survival of species.
- Water is needed to run industries and factories.
- Thermal power energy generation is linked to water evaporation technology.
OVER-EXPLOITATION OF GROUNDWATER
- Groundwater is the most important source of water and is renewable but it takes a minimum of 10-15 years to renew naturally.
- Mankind has always been a liability. The current rate at which we are destroying the groundwater is hazardous.
- Three types of effects
(i) Subsidence: When groundwater usage is more than its recharge, the sediments in the aquifer get compacted, a phenomenon known as ground subsidence.
- Abundant economic losses may occur due to this phenomenon because it results in the sinking of overlying land surface.
- The problems associated with this phenomenon include structural damage in buildings, fracture in pipes, reversing the flow of sewers and canals, and tidal flooding.
(ii) Lowering of water table: Mining of groundwater is done extensively in arid and semi-arid regions for irrigating crop fields. But it is not advisable to do excessive mining as it would cause a sharp decline in future agricultural production, due to lowering of the water table.
(iii) Waterlogging: When excessive irrigation is there with brackish water it raises the water table gradually leading to water-logging and salinity problems. This destroys vegetation and agriculture thus concurrent farmer suicide.
Over Exploitation of Surface Water
- Surface water is often misused, due to which its quality and quantity both degrades.
- Since lakes, ponds, rivers, seas are used for dumping industrial and sewage wastes, dead bodies, solid wastes, etc. hence their quality degrades.
- There are many reasons for this:
(i) Population growth:
With the ongoing increase in population growth especially in developing countries like India, China, Thailand, etc. water demand will increase unless there are corresponding increases in water conservation and recycling of this vital resource.
(ii) Expansion of Industrial activity:
Industrial activity ranging from industrialization, tourism, and entertainment expansion. This requires excessive water services including both supply and sanitation and other necessary uses which lead to more pressure on water resources and natural ecosystems.
(iii)Â Rapid urbanization:
Urbanization is increasing at a rapid pace.  Small private wells and septic tanks that work well in the low-density population are not feasible within high-density urban areas. Urbanization asks significant investment in water infrastructure in order to deliver water to individuals and to process the concentrations of wastewater – both from individuals and from businesses. These polluted and contaminated waters must be treated as they pose hazardous public health risks.
(iv) Climate change:
Global warming and Carbon cycle imbalances are deteriorating Planet Earth.
Climate change could have significant impacts on water resources around the world because of the close connections between the climate and the water cycle. Increasing temperatures will increase evaporation which further increases precipitation, though there will be regional variations in rainfall. This would be hazardous because of unnecessary flooding in low-lying areas.
Overall, the global supply of fresh water will increase.
For example: Every year variation in rainfall causes Kosi river and Brahmaputra River to cross their embankment. This leads to floods in Assam and Bihar, India.
Higher temperatures will also affect water quality in many ways. Â Possible impacts include increased Eutrophication. Climate change could also mean an increase in demand for farm irrigation.
(v) Pollution:
Pollution results in the corruption of water. Water dumped with garbage, pesticides, fertilizers, animal waste, dead bodies, etc. is useless. The water is unfit for consumption due to increasing high metal toxins especially in rivers near the nuclear power plant.