On Page 25
Question 1. From your everyday experiences, write a short proposal on how you can conserve water?
Answer: We can conserve water at home and in the school by the following methods –
- Do not leave the tap running while brushing your teeth or washing your face.
- Use a bucket for bathing, not a running tap.
- Do not flush the toilet unnecessarily.
- Ensure all the taps are without any leakage.
- Water which has been used for washing vegetables, dal, rice etc should not be thrown away. It can be used for watering potted plants or garden plants.
- Promote water conservation by forming a group of water conscious persons with friends and neighbours. Hold regular meetings and exchange ideas promoting water conservation.
On Page 27
Question 1. Find out more about any one traditional method of building dams and irrigation works.
Answer: In Meghalaya, an ingenious system of tapping stream and spring water by using bamboo pipes is used to irrigate plantations of betel leaf or black pepper crops. The tribes of the Khasi and Jaintia hills have been using this from the last 200 years. About 20 litres of water enter the bamboo pipe system per minute and may travel almost a kilometre to finally reach the plants near its roots.
Bamboo pipes are used to take water from perennial springs on the tops of the hills to the plantations by using gravity. Reduced channel sections and diversion units are used at the last stage of water application.
On Page 29
Question 1. Make a list of inter state water disputes.
Answer : The major inter state water disputes are –
- Ravi Beas river water dispute between Punjab, Haryana and Rajasthan.
- Kaveri river water dispute between Tamil Nadu and Karnataka.
- The Krishna river water dispute between Maharashtra, Karnataka and Andhra Pradesh.
On Page 33
Question 1. Collect information on how industries are polluting our water resources.
Answer: Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment. Many industrial facilities use the river water to carry away waste from the plant the oceans.
Pollutants from industrial sources include –
- Asbestos This pollutant is a serious health hazard and carcinogenic. Asbestos fibres can cause illnesses such as lung cancer, intestinal cancer and liver cancer.
- Lead It can cause health and environmental problems. It is a non-biodegradable substance and is hard to clean up once the environment is contaminated. Lead is harmful to the health of many animal including humans, as it can inhibit the action of bodily enzymes .
- Mercury can cause health and environmental problems. It is a non -biodegradable substance and so is hard to clean up once the environment is contaminated. Mercury is also harmful to animal health as it can cause illness through mercury poisoning.
- Sulphur This is a non-metallic substance that is harmful for marine life.
- Oils Oil does not dissolve in water; instead it forms a thick layer on the water surface. This can stop marine plants receiving enough light for photosynthesis. It is also harmful for fish and other marine animals.
- Petrochemical Products They are formed from use of natural gas or other fuels in industry and can be toxic to marine life.
Question 1. Multiple choice questions.
(i) Based on the information given below, classify each of the situations as ‘‘suffering from water scarcity’ or’ not suffering from water scarcity.
- Region with high annual rainfall
- Region having high annual rainfall and large population
- Region having high annual rainfall, but water is highly polluted
- Region having low rainfall and low population
( ii) Which one of the following statements is not an argument in favour of multi-purpose river projects ?
- Multi-purpose projects bring water to those areas which suffer from water scarcity.
- Multi-purpose projects by regulating the water flow help to control floods.
- Multi-purpose projects lead to large-scale displacements and loss of livelihood.
- Multi-purpose projects generate electricity for our industries and our homes.
(iii) Here are some false statements. Identify the mistakes and rewrite them correctly.
- Multiplying urban centres with a large and dense population and urban lifestyle have helped in proper utilisation of water resources.
- Regulating and damming of rivers does not affect the river’s natural flow and its sediment flow
- In Gujarat, the Sabarmati basin farmers were not agitated when higher priority was given to water supply in urban areas, particularly during droughts.
- Today in Rajasthan, the practice of rooftop rainwater harvesting has gained popularity despite high water availability due to the Rajasthan canal.
(i) (1) Not suffering from water scarcity.
(2) Suffering from water scarcity.
(3) Suffering from water scarcity.
(4) Suffering from water scarcity.
- Multiplying urban centres with a large and dense population and urban lifestyle have not only added to water and energy requirements, but have further aggravated the problem.
- Regulating and damming of rivers affects their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the river’s aquatic life.
- In Gujarat, the Sabarmati basin farmers were agitated, and almost caused a riot over the higher priority given to water supply in urban areas, particularly during droughts.
- Today, in Western Rajasthan, the practice of rooftop rainwater harvesting is on the decline as plenty of water is available due to the perennial Rajasthan canal, though some houses still maintain the tanks since they do not like the taste of tap water.
Question 2. Answer the following questions in about 30 words.
- Explain how water becomes a renewable resource.
- What is water scarcity and what are its main causes?
- Compare the advantages and disadvantages of multi-purpose river projects.
- Water becomes a renewable resource through the hydrological cycle. Fresh water is mainly obtained from the surface run off and groundwater is continually being renewed and recharged through the hydrological cycle.
- Water Scarcity Shortage of water as compared to its demand is known as water scarcity. The main causes of water scarcity are as follows.
The main causes of water scarcity are as follows –
(a) Growing Population A large population means more water requirement for cooking, washing and bathing.
(b) Industrialisation The ever increasing number of industries pressure on the existing freshwater resources. Industries are heavy users of water.
(c) Commercialisation of Agriculture Commercial crops need more water and other inputs. Assured means of irrigation like tube wells and canals are responsible for the falling of ground water levels.
- The various advantages and disadvantages of multi-purpose river projects can be compared as given in the table below –
Question 3. Answer the following questions in about 120 words.
- Discuss how is rainwater harvesting in semi-arid regions of Rajasthan carried out.
- Describe how are modern adaptations of traditional rainwater harvesting methods being carried out to conserve and store water?
- In semi-arid regions of Rajasthan every house had underground tanks to store the water for drinking purposes. These tanka s are large and deep tanks which were built inside the main house or the courtyard. They were linked to the sloping roofs of the houses through a pipe. Rainwater falling on the rooftops would run down through the pipe and collect in the underground tanks.
The rainwater collected was stored in the underground tanka s providing drinking water till the next seasons. When all other sources have dried up, these tankas were beneficial to beat the summer heat as they kept the rooms cool. Rainwater or polar pani, as it was commonly known in these parts, is considered the purest form of natural water.
2) Modern adaptations of traditional rainwater harvesting include –
(a) Rooftop rainwater harvesting’ is practiced in semi-arid areas of Rajasthan to store drinking water.
(b) In hills and mountainous regions people build diversion channels like that in the Western Himalayas for agriculture.
(c) In arid and semi-arid regions, agricultural fields were converted into rainfed storage structures that allowed the water to stagnate and moisten the soil like the ‘Khadins’ in Jaisalmer and the ‘Johads’ in other parts of Rajasthan.
(d) In the flood plains of Bengal, people developed inundations on channels to irrigate their fields.
(e) Bamboo drip irrigation system is also being used in Megha laya and other states in the North-East of India.