Page 146 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

v A few metres under the ground, water collects between soil particles and between spaces

in the rocks. The upper level of this layer of rocks and soil is called water table.
v The process of water seeping into the ground is called infiltration.

v Water also collects between the hard rocks below the ground. This is called the aquifer.
v Rainwater is the main source of groundwater. It is the purest source of water.
v If we draw as much groundwater as is replenished naturally, the water table remains

unaffected. This is called depletion of water table.
v The causes of depletion of groundwater are: industrial activities, increase in population,

decrease in rainfall, deforestation and agricultural activities.
v The places that receive very little or no rainfall face scarcity of water. People in such areas

have to walk several kilometres to fetch water.
v In cities and towns, most households get water through a network of pipes. In most Indian

villages, however, such a network for water supply does not exist. Villagers fetch water from
tube wells, wells and hand pumps.
v Water management includes providing safe drinking water (known as potable water) in

adequate amount to everyone.
v Rainwater harvesting is considered the best way to collect rainwater. This can be done

efficiently by constructing percolation pits and recharging wells. This water can be pumped
out in times of water shortage.

v When rainwater is collected from the roofs of the buildings and guided into underground
reservoirs through pipelines, it can be used when needed. This is called rooftop rainwater

harvesting.
v In olden days, people built deep step wells into the ground called baori or baoli. This was a
traditional way of collecting rainwater.

v Drip irrigation is a type of irrigation that allows water to drip slowly to the roots of plants
either from above the soil surface or is buried below the surface.

v Afforestation is the practice of transforming an area, usually a barren land, into a forest.
v A water reservoir is an enclosed area for the storage of water to be used in future.
v Water is essential for plants to prepare food and grow. They are the primary producers in

the food chain and the ultimate source of oxygen for life to survive. The absence of plants
will eventually lead to the end of all life on Earth.

Exercise

A. Tick (3) the correct answer.

1. What is/are the main source(s) of water?
(a) Rainwater (b) Glaciers (c) River water (d) All of the above

Ans. (d)

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