NCERT Solutions Economics Class Ten Chapter 3
Chapter 3: Water Resource
3. Answer the following questions in about 120 words.
(i) Discuss how rainwater harvesting in semi-arid regions of Rajasthan is carried out.
(ii) Describe how modern adaptations of traditional rainwater harvesting methods are being carried out to conserve and store water.
Ans. (i) In some of the semi-arid regions of Rajasthan, agricultural fields are converted into rain-fed storage structures that allowed water to stand and moisten the soil. These structures are locally known as ‘johads’. In the arid areas of Jaisalmer such structures are known as ‘khadins’.
In the semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, almost all the houses, traditionally, had big underground tanks called ‘tankas’ for storing drinking water.
The tankas were part of the well-developed rooftop rainwater harvesting system. The tanks could be as large as a big room. Rainwater, commonly known as ‘palar pani’ in local language was stored for drinking purpose.
The water was collected by channelising rainwater through pipes from the sloping rooftop to the underground tanks built inside the house or courtyard.
The first spell of rain was usually not collected as it would clean the roofs and pipes. As a result it would be dirty, and unfit for drinking purpose.
The rainwater from the subsequent showers was then collected and stored in the tankas till the next rainfall, making it an extremely reliable source of drinking water when all others sources dried up, particularly during summers.
Many houses constructed underground rooms adjoining the tankas to combat the summer heat as it would keep the rooms cool naturally.
The practice of rainwater harvesting, is however, declining in western Rajasthan at present because the perennial Indira Gandhi Canal or Rajasthan Canal provides plenty of water to the region, throughout the year.
(ii) Rooftop rainwater harvesting in Gendathur village of Mysuru, Karnataka, is an example of modern adaptation of traditional rainwater harvesting methods being carried out to conserve and store water. Gendathur is a remote, backward village which has earned the rare distinction of being rich in rainwater because of successful rainwater harvesting by the villagers.
Gendathur receives an annual precipitation of 1000 mm. The villagers have utilised this rainwater to meet their water need by collecting it through rooftop rainwater harvesting system in their individual houses. Nearly 200 households in the village have installed the system. As such, with 80 per cent of collection efficiency of the annual precipitation and about 10 fillings of rain, every house in Gendathur can collect and use about 50,000 litres of water annually. The net amount of rainwater estimated to be harvested annually from all the households amount to 10,00,000 litres.
Tamil Nadu is the first and the only state of India which has made modern rooftop rainwater harvesting structure compulsory to all houses acrosss the state.
Recharging of groundwater by means of dug wells, pits, hand pumps etc., is a new concept of rainwater harvesting being adopted in many areas to conserve and store water.