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.