Basic Science Solutions for Class 7 Science Chapter 16 Water Scarcity And Conservation are provided here with simple step-by-step explanations. These solutions for Water Scarcity And Conservation are extremely popular among Class 7 students for Science Water Scarcity And Conservation Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Basic Science Book of Class 7 Science Chapter 16 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Basic Science Solutions. All Basic Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

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Sources such as streams and tanks in which water is present on the surface of earth, constitute the surface water sources. Some sources of surface water are ponds, lakes, rivers, canals and man-made tanks.

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Traditionally, groundwater was drawn out by digging wells. Nowadays, groundwater is extracted from ground by using electric pumps or tube wells.

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Tanks are used for storing water and irrigation purposes in parts of Bihar, Madhya Pradesh and Rajasthan.

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Excessive use of groundwater leads to the depletion of groundwater level of an area, which finally dries up the wells.

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Causes for scarcity of water in our country:
(i) Uneven pattern of rainfall
(ii) Overuse and deforestation
(iii) Loss of water through runoff and water pollution

Page No 156:

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The rainwater or water from other forms of precipitation, that gets trapped between the soil particles in the pores present in the soil, is called soil moisture.
Soil moisture is important to sustain the growth of plants because they absorb this water through their roots.

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Rain, falling on the soil in an area, fill up the pores between the soil particles. When these pores get saturated completely, the water seeps further downward to finally reach the impenetrable layer of big hard rocks. This water keeps getting stored there and forms groundwater.

The uppermost level of groundwater, at a depth measured from the ground surface, is called the water table.

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Rainfall in our country is not evenly distributed. Moreover, at times, rains are also much scantier than the average rainfall. Besides, rainfalls are also limited to monsoons. All these characteristics of rainfall lead to the scarcity of water despite good rainfall.

Tamil Nadu and Kerala receive rainfall twice a year.

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Rainwater cannot be brought completely under direct use. Approximately, 40 % of this water gets stored as groundwater. 30 %  of this water forms a part of soil moisture. About 20% of this water is lost by evaporation. Rest 10% forms a part of the runoff, which finally reaches seas and oceans through streams and rivers. Some of the water also gets stored in man-made and natural water bodies such as wells and ponds. Thus, all the rain falls on an area cannot be utilized completely.

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Vilasrao Salunkhe borrowed the idea of constructing check-dams on streams from village farmers in some parts of Maharastra, to use the runoff water during rains to recharge wells. He applied this idea on 16 hectares of land on a hill slope, which was granted to him on lease by a temple.
He created bunds on the slope of the hill with the help of some final-year engineering students and retired engineers. These bunds acted as check-dams to collect the runoff water into a percolation tank that was constructed at the base of the hill. This percolation tank recharged the groundwater that in turn recharged the surrounding wells.

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Following steps can be taken by the people of a place to get over the scarcity of water:

(a) To overcome the scarcity of water, it is needed to check the overuse of water. It is reported that in metropolitan cities, an individual uses an average of 400 litres of water a day, whereas in the adjoining areas, an individual uses an average of only 20 litres of water per day.
(b) Water pollution should be brought under control to conserve water bodies.
(c) Deforestation in the hilly regions should be checked as it leads to water loss as runoff.
(d) Construction of bunds on slopes of hills is a useful method to reduce runoff as well as soil erosion.

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1. Groundwater gets collected in the spaces between impervious rocks.
2. About 50% of our agricultural needs are met by groundwater.
3. A percolation tank allows water to seep into the soil and recharge groundwater.
4. The area from which water drains into a river or stream is its catchment area.
5. When surface water bodies get polluted, people turn to groundwater to meet their needs.
6. Tanks are a very important source of water in southern and western India.

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1. False. Tanks and wells are major sources of water in Rajasthan.  
2. True. About 20 per cent of rainfall is lost due to evaporation.
3. False. Ground water is also used for various purposes, such as drinking and in industries.
4. False. Surface water is the main source of water in Himalayan states.
5. False. Average rainfall in our country is much higher than the world average.



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