Earth’s water distribution and Indian scenario

Earth water distribution“Water is life”. It is a unique natural resource among all sources available on  earth.  No life form can be sustained without water on the planet. It is essential for all the important activities like food production, industries like energy, production and manufacturing. It plays an important role in economic development and the general well being of the country.

United Nations stated that water is a social and cultural good, not merely an economic commodity. Chemically water is a compound of oxygen and hydrogen with highly distinctive physical and chemical properties. It has chemical formula:  H2O.

Out of all the water available on the Earth, 97 % of water is saline and is in oceans, 3% of water is freshwater available in rivers, streams and glaciers. There is enough freshwater available on the planet for current population of the world but it is distributed unevenly. Following graph shows the Earth’s water distribution.

Detail estimate on global water availability;

Detail estimate on global water availability

Indian Scenario:

Surface water resources: Water resources including rivers, lakes or fresh water wetlands are known as surface water resources. Precipitation is the natural recharging source for the surface water resources and it also maintain the hydrological cycle.  Rivers are the major source of water in India. The utilizable annual surface water in rivers of the country is 690 km3. Human activities like artificial dams, reservoirs are also included in the same category and have capacity to increase utilization of the water.

 

(Source: Water resources of India, Current Science, Vol. 89, No. 5, 10 September 2005, by Rakesh Kumar, R. D. Singh and K. D. Sharma )

Groundwater resources: Water sources like subsurface water or water within aquifers are  known as ground water resources.Ground water resource recharge from the precipitation mostly in the monsoon season n India. Canal irrigation and other form of irrigation systems  also contribute to the recharging of the ground water. The annual potential of natural groundwater recharge from rainfall in India is about 342.43 km3, which is 8.56% of total annual rainfall of the country. The annual potential groundwater recharge augmentation from canal irrigation system is about 89.46 km3 (Rakesh Kumar, R. D. Singh and K. D. Sharma)

Water Availability and Quality in India:Water is available only for a few hours in most Indian cities and the quality is also not up to the mark.Water woes are also because of insufficient or low pressure and erratic supplies.The rural population suffers from low water quality but the urban and semi- urban areas are most prone to water shortage.The water quality should be safe and sound at the microbiological level and mere continuous supply is not enough. Another aspect is the water wastage in terms of leakages and illegal connections.

Table below shows the water quality criteria by CPCB;

Designated-Best-Use

Class of water

Criteria

Drinking Water Source without conventional treatment but after disinfection

A

  • Total Coliforms Organism MPN/100ml shall be 50 or less
  • pH between 6.5 and 8.5
  • Dissolved Oxygen 6mg/l or more
  • Biochemical Oxygen Demand 5 days 20°C 2mg/l or less
Outdoor bathing (Organised)

B

  • Total Coliforms Organism MPN/100ml shall be 500 or less pH between 6.5 and 8.5 Dissolved Oxygen 5mg/l or more
  • Biochemical Oxygen Demand 5 days 20°C 3mg/l or less
Drinking water source after conventional treatment and disinfection

C

  • Total Coliforms Organism MPN/100ml shall be 5000 or less pH between 6 to 9 Dissolved Oxygen 4mg/l or more
  • Biochemical Oxygen Demand 5 days 20°C 3mg/l or less
Propagation of Wild life and Fisheries

D

  • pH between 6.5 to 8.5 Dissolved Oxygen 4mg/l or more
  • Free Ammonia (as N) 1.2 mg/l or less
Irrigation, Industrial Cooling, Controlled Waste disposal

E

  • pH betwwn 6.0 to 8.5
  • Electrical Conductivity at 25°C micro mhos/cm Max.2250
  • Sodium absorption Ratio Max. 26
  • Boron Max. 2mg/l
 

Below-E

  Not Meeting A, B, C, D & E Criteria

 

“The water quality monitoring results obtained during 1995 to 2006 indicate that the organic and bacterial contamination are continued to be critical in water bodies. This is mainly due to discharge of domestic wastewater mostly in untreated form from the urban centres of the country. The municipal corporations at large are not able to treat increasing the load of municipal sewage flowing into water bodies without treatment. Secondly the receiving water bodies also do not have adequate water for dilution. Therefore, the oxygen demand and bacterial pollution is increasing day by day. This is mainly responsible for water borne diseases.” (CPCB- http://cpcb.nic.in/water.php)

Water which follows the above standards can be considered as available water for all.

Know more about Water scarcity in India