WATER RESOURCES

 Water is an indispensable natural resource on this earth on which all life depends. About 97% of the earth's surface is covered by water and most of the animals and plants have 60-65% water in their body.

WATER IS A UNIQUE RESOURCE

Water is characterized by certain unique features which make it a marvellous resources:

• It exists as a liquid over a wide range of temperature i.e. from 0°C to 100°C.
• It has the highest specific heat due to which it worms up and cool down very slowly without causing shocks of temperature jerks to the aquatic life.
• It has a high latent heat of vaporization. Hence, it takes a huge amount of energy for getting vaporized. That's why it produce a cooling effect as it evaporates.
• It is an excellent solvent for several nutrients. Thus, it can serve as a very good carrier of nutrients, including oxygen, which are essential for life. But, it can also easily dissolve various pollutants and become a carrier of pathogenic microorganisms.
• Due to high surface tension and cohesion it can easily rice through great heights through the trunk even in the tallest of the trees like SEQUOIA.
• It has an anamalous expansion behaviour i.e. as it freezes, it expands instead of contracting and thurs becomes lighter. It is because of this property that even in extreme cold, the lakes freeze only on the surface. Being lighter the ice keeps floating, where as the bottom waters remain at the higher temperature and therefore, can sustain aquatic organisms even in extreme cold.

The  Hydrological Cycle Continuously Purifies, Recycle And Distributes Fresh Water

The water we use keeps on cycling and Leslie through the environment which we call as Hydrological Cycle. We have enormous resources of water on the earth a mountain to about 1404 million kilometre^3. The water from various moist and wet surfaces evaporates and false again on the earth in the form of rain or snow and passes through living organism and ultimately returns to the oceans. Every year about 1.4 inch thick layer of water evaporates from the oceans more than 90% of which returns to the ocean through the hydrological cycle. Solar energy drive the water cycle by evaporating it from various water bodies which subsequently return through rainfall or snow. Plants to play a very important roll by observing the groundwater from the soil and releasing it into the atmosphere by the process of transpiration.

          Global distribution of water resources is quite uneven depending upon several geographic factors. Tropical rainforest areas receive maximum rainfall while the major world deserts occur in zone of dry descending year (20-40°N and S) and receive very little rainfall.

Water Availability

Although water is abundant on this earth, yet it is very precious. Out of the total water reserve of the world about 97.4% is salty water (marine) and only 2.5% is fresh water. Even this small fraction of freshwater is not available to us as 68.7% of it is locked up in polar caps(1.98%) and just 30.1% of it is readyly available to us in the form of groundwater. Only 1.2% is available in the form of surface water ( rivers and lakes) and other fresh water sources such as groundwater, ice, permafros water in atmosphere in the living organisms, swaps marshes and soil moisture.

OCEANS: Oceans are ultimate sinks for all types of water. About 97.4% of total water is present in oceans. Salt content of oceans is about 3.5%. seawater is not fit for human consumption and other anthropogenic activities without desalination.

GLACIERS AND ICE: Amazon part of available approximately 2.5% of freshwater is locked up into glaciers and ice caps. These occur at high altitude or high latitude. Antarctica glacier contain approximately 85% of all the world's ice. About 10% is made by Greenland ice-sheet and Arctic ice. Rest 5% is in the form of snow or mountain peaks.

          As per the UNICEF and World health organisation (WHO) report at least 2.2 million people around the world do not even have access to safely manage drinking water service. Increasing population and expanding development wool for the increase the demand for water. It is estimate that two thirds of population world be suffering from acute water shortage.

Surface Water

The water coming through precipitation when does not percolate down into the ground or does not return to the atmosphere as evaporation or transpiration loss, assumes the form of streams, lakes, ponds,wetlands or artificial reservoirs known as Surface Water 

           The surface water is largely used for irrigation, industrial use, public water supply, navigation etc. A country's economy is largely dependent upon its rivers. All are early civilization are recorded near big rivers. Even now we find that development activities florist near rivers.