Friends in our previous session we have studied about the hydrological cycle or water cycle.
If you remember we had said that, evapo-transpiration,
condensation and precipitation(snowfall or rainfall)
Are the three main parts of the water cycle.
Where precipitation happens to be the main source of water for the earth
This rain and snow that falls on the earth either end up as: surface run off $ infiltration.
So what is surface run off?
? It is the water that flows off to various water bodies on the land, to form the SURFACE
WATER.
The examples of surface water include- seas, oceans, rivers, lakes, ponds etc.
It can be saline water (seas and oceans) or fresh water (rivers, lakes ponds).
These surface waters are naturally replenished through precipitation and lost through discharge
into seas, evaporation, also some amount of water seeps into the ground.
? Apart from this, some amount of rainwater also seeps down or percolates into the ground.
As the water moves down the soil particles or the spaces between the soils are full of
water.
This level of ground saturation is called as water table.
The water that is found there is called as GROUNDWATER.
The rock structure that holds this groundwater is called an aquifer.
Friends, have you all seen a sponge?
It has many tiny pores in it and the water that it soaks is stored in these spaces.
An aquifer resembles a sponge in natural conditions.
Friends before we move ahead, a question POPPED in my mind..is ground water freshwater or
saline water?
Yes it is a freshwater source and makes up to 30% of the worlds fresh water supply.
Because of it being a freshwater SOURCE, Some people picture groundwater as an underground
river or lake.
So here we can say that precipitation (rainfall/snowfall) is the main source of water which is available
to us in the form of surface water and groundwater.
We can satisfy our various needs like drinking, washing, cleaning, cooking, or other uses
like irrigation, industrial use, or for transportation, fisheries, tidal energy generation etc from
these fresh as well as marine water resources.
Distribution of water: Well lets proceed and see how precipitation
(rainwater or snow) which is the main source of water for the whole earth, is allocated
or distributed considering the example of India.
India receives precipitation in the form of rainfall from the monsoon winds (south west
and north east monsoon winds) and the snow from the Himalayan mountain ranges.
This rain and snow is finally available to us in the form of surface and ground water.
Surface water sources in India includes a large network of rivers like
Himalayan River, rivers of Deccan plateau, coastal rivers and inland drainage basins.
All these are sources of fresh water.
India also forms a peninsular to its south as it is surrounded on three sides by seas,
which contribute to the marine water resources of the country.
(east bay of Bengal, west- Arabian sea, south- Indian ocean)
Talking about groundwater sources, India does not have large continuous aquifers.
But the coastal plains and the low-lying areas of mountain valleys are a rich source of groundwater.
So we can say India is blessed with almost all types of water sources.
But friends if we observe there are certain factors that directly or indirectly influence
the water distribution like location of a country, its climate, the surface structures
like mountains, plateaus, plains, deserts etc or in other words topography, the structure
of rocks or aquifers, and a countries proximity or nearness to the sea.
And these factors vary from place to place like if we consider Saudi Arabia, a country
located in the middle east; owing to its hot and dry climate, it receives very little or
infrequent rainfall.
Therefore, it has no permanent rivers or lakes and has very few natural aquifers.
What then is their main source of water?
Because of the proximity to the sea, 50% of the drinking water is obtained by desalination
procedures.
Although being an oil rich country; it is water poor.
Well friends, these are a few factors which influence the water distribution throughout
the globe, making a country water-rich or water-poor.
Hence, we can conclude the water distribution throughout the globe is uneven
That means certain areas have a large natural supply of water whereas some areas have scarce
water resources which leads to an uneven distribution of water.
There are certain places in this world where people do not have access to clean drinking
water.
We hear cases where people walk miles just to find a water source.
There are places where people lose their agricultural crop because it didnt rain the entire year.
Water is the foundation of life but water scarcity is a nightmare in many parts around
the world.
To know the factors that are causing this shortage or scarcity of water do tune into
us and watch the next session, where we will also be seeing the various ways by which we
can conserve water.
Thank you.
We never know the worth of water till the well is dry.