Grade 7 | Science | Water- A precious resource, Natural resources and their conservation, Olympiad, CBSE, ICSE, SOF, ITO
Significance of water
Water plays a crucial role in the survival of life on earth. It forms a basis of life without which no one can imagine to survive for long. As you know the Earth has 3/4 amount of its surface occupied with water only. Out of this such a great amount of water, only 3% of the water is the freshwater which can be used for consumption rest of the 97% of the water is saline in nature.
The surface water is also present in three forms i e Lakes, Rivers and Swamps.
Such a small amount of water is fit for consumption is present on earth and still, people waste gallons of water while brushing the teeth. We should make people aware of such water scarcity and ask them not to waste this precious resource on which the future of mankind is dependent on.
Groundwater, an important source of water
It is the most important source of water for us. The water is stored between the layers of rocks under the ground. The upper limit of groundwater at a placed is what we call as water table of that place. In plains, the water table is usually high in comparison to the plateaus where it is very low. This is the reason why it is easier to install handpump in northern plains.
Maintenance of groundwater
The main source of groundwater is the rainfall and the water from the adjoining water bodies like ponds, rivers, lakes, etc. Water slowly seeps and move downwards into the ground. This process of seeping of water into the lowest layers of the ground is called infiltration. The movement of water through the gaps between the soil particles is called percolation. This helps in recharging the groundwater.
A percolation tank allows rainwater to seep into the deepest layers of ground and helps in recharging the groundwater.
Aquifer - It is the water stored between the hard rock layer below the water table. This is the water which is pumped through the hand pumps or tube wells.
We can restore the groundwater by seeping the rainwater with the help of percolation tank through the soil and by using the groundwater judiciously.
Depletion of the water table
Due to the growing human population, the demand for potable water has been increased. The need for drinking water is increasing day by day along with an increase in the need for water in irrigation, economic activities, and recreation.
Most of the places are facing acute shortage of water due to depletion of the water table.
As the population is growing them for more food grains has also increased. The farming is being done on a larger scale which means more consumption of water by irrigation.
The growing population has lead to more construction of the pucca houses and roads which does not allow the rain water to seep in as the concrete layer is impervious. This does not allow the natural recharge of underground aquifers.
Deforestation has also lowered the recharge of groundwater. As trees make the rocks previous to water and facilitate the recharge of underground aquifers.
Conservation of water
It is very important to recharge the groundwater as we will be facing an acute shortage of potable water in the near future. For this, we can use the rainwater to recharge the groundwater rather than letting it run off into the sea. This is known as rainwater harvesting. It can be used to raise the levels of groundwater in arid areas.
Rainwater harvesting is all about the collection of rainwater for its future use. In many parts of India especially in the northwestern part, like Rajasthan tanks and bawris had been used for collecting rainwater from ancient times. Tanka is an underground tank to collect rainwater whereas bawri is an open tank in which water is used to be collected.
Rainwater harvesting can also be done in modern homes. The runoff water from the rooftop should be collected in an underground reservoir. These reserves are to be filled with sand and gravel to filter the impurities from water. This water can either be used directly can be used to recharge the underground water.