WATER RESOURCES
Main points to remember:
1. Three-fourth of the earth’s surface is covered with water.
2. 97.5 per cent of the total volume of world’s water exists as oceans.
3. Only 2.5 per cent is fresh water.
4. Nearly 69 per cent of this freshwater occurs as ice sheets and glaciers in Antarctica, Greenland and the mountainous regions of the world,
5. 30 per cent is stored as groundwater and less than 1 per cent is in lakes and rivers.
6. Freshwater is mainly obtained from surface run off and ground water.
7. Water is continually being renewed and recharged through the hydrological cycle thus water is a renewable resource.
8. India receives nearly 4 per cent of the global precipitation and ranks 133 in the world in terms of water availability per person per annum.
9. The availability of water resources varies over space and time, mainly due to the variations in seasonal and annual precipitation.
10. But water scarcity in most cases is caused by over- exploitation, excessive use and unequal access to water among different social groups.
11. Over-exploitation of groundwater for growing more crops lead to falling groundwater levels, lesser water availability and food insecurity in the country.
12. Situation where water is sufficiently available to meet the needs of the people, but, the area still suffers from water scarcity is due to water pollution.
13. 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.
14. In Shillong nearly every household in the city has a roof top rain water harvesting structure and 15-25 per cent of the total water requirement of the household comes from roof top water harvesting.
15. In Gendathur, a remote backward village in Mysore, Karnataka, villagers have installed in their household’s rooftop rainwater harvesting system to meet their water needs.
16. Tamil Nadu is the first and the only state in India which has made roof top rainwater harvesting structure compulsory to all the houses across the state. There are legal provisions to punish the defaulters.
17. In Meghalaya, a 200-year-old system of tapping stream and spring water by using bamboo pipes is common.
Dam: A barrier across the flowing water.
Groundwater:- Water which is obtained from a depth of more than 15 m is known as groundwater.
Multipurpose Project:- A river valley project which serves a number of purposes simultaneously such as irrigation, flood control and generates hydroelectricity. Eg. Bhakra Nangal.
Perennial Canals: Canals developed by diverting water from rivers that flow throughout the year.
Rainwater Harvesting:- it is a technique of increasing the recharge of groundwater by capturing and storing rainwater, by constructing structures such as percolating pits, check dams etc.
Drip Irrigation:- A type of irrigation were water gets dropped in the form of drops near the roots of the plant mainly to conserve the moisture.
Inundation Canal:- Canal meant for diverting flood waters mainly during the rainy season.
Seepage: - The slow movement of water through small cracks, pores, interstices etc. in the surface of unsaturated material into or out of a body of surface or subsurface water is known as seepage.
River Basin: - The total area drained by a river and its tributaries iscalled a river basin
Potential Water Resources: - Potential water resources are the total amount of water resources that can be developed for useful purposes.
Watershed Management:- refers to efficient management and conservation of surface and groundwater resources.
Rainwater harvesting:- It is a technique developed to store the rainwater, river water or groundwater to meet the needs of the population.
River water disputes:- Disputes concerned with the sharing of river water between states flowin through several states in India.
EXPLANATION:
Water is an important natural resource. It is the basic need of human beings and considered as the wealth of a nation. Water is needed for irrigation, generation of power, industries, domestic use, navigation, fisheries and recreational purposes. Water scarcity is possibly to pose the greatest challenge on account of its increased demand coupled with shrinking supplies due to over utilisation and pollution. Water is a cyclic resource with abundant supplies on the globe. Approximately, 71 per cent of the earth’s surface is covered with it but fresh water constitutes only about 3 per cent of the total water. In fact, a very small proportion of fresh water is effectively available for human use. The availability of fresh water varies over space and time. The tensions and disputes on sharing and control of this scare resource are becoming contested issues among communities, regions, and states. The assessment, efficient use and conservation of water, therefore, become necessary to ensure development.
The use of water resources is not new to humankind. The development of water resources is very essential to satisfy the needs of growing population and as a natural resource, its judicious conservation is required. Now a days rain water harvesting is given due importance. The chief sources of surface water are rivers and lakes. The underground water sources are wells and springs. The availability of water varies from place to place and from time to time. India depends on rainfall and snowfall for surface water and underground water. Rainfall in India is uncertain, unevenly distributed and seasonal. Therefore, to carry on agriculture, India depends on canals, tanks and wells. They are very essential wherever the water is scarce. This method of supplying water artificially for agriculture is called irrigation. Irrigation is very important in India agriculture is the main occupation of the people and rainfall is insufficient. One of the greatest achievements in the history of agriculture is the practice of irrigation. The perennial rivers of North India and the underground water resources of the Great Plains of the north have helped in the development of irrigation.
Different regions have different types of irrigation, depending upon the source of water. The distribution of rainfall, relief features and the requirement of water for different crops are the factors affecting the practice of different types of irrigation. The major types of irrigation practised in India are:-
1) Well irrigation,
2) Tank irrigation,
3) Canal irrigation.
(1) Tanks mostly depend on rain water. They are filled with water only during the rainy season and became dry during summer when water is most needed
(2) Silt accumulates in tanks and desilting becomes necessary. In Karnataka, desilting of tanks is being has been carried out.
CANAL IRRIGATION: Canal irrigation is mostly practised in North India where perennial rivers flow. India has the largest network of irrigation canals. 39% of the total irrigated area is covered by canal irrigation. The flat surface of North India, perennial rivers, vast agricultural land, have become important factors for the development of canal irrigation. The construction and maintenance of canals requires huge capital, hence they are under the control of the government. There are two types of canals. They are non-perennial (inundation) canals and perennial canals. Dams are constructed across the rivers in the perennial canals. They store water in reservoirs and provide it for agriculture through canals. Canals taken out directly from the rivers are called non-perennial canals. In India, Punjab, Haryana, Rajasthan, West Bengal, Orissa, Andhra Pradesh, Tamilnadu and Maharashtra have canal irrigation. Uttar Pradesh has the largest network of irrigation canals.
PROJECTS:
1. In the first century B.C., Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
2. During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
3. Evidences of sophisticated irrigation works have also been found in Kalinga, (Orissa), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka), Kolhapur (Maharashtra), etc.
4. In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time was built.
5. In the 14th Century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.
6. Dam is a barrier across flowing water that obstructs, directs or retards the flow, creating a reservoir or lake.
7. The Bhakra – Nangal project on Sutluj-Beas River is used both for hydel power production and irrigation.
8. Similarly, the Hirakud project in the Mahanadi basin integrates conservation of water with flood control.
9. The troubles faced by people owing to the flooding of Damodar River have given this river a name as the river of sorrow.
10.Jawaharlal Nehru proudly announced the dams as the ‘temples of modern India’.
11.He called dams as temples because he thought they will integrate the agriculture and village economy with industrialization and urban economy.
12. Sardar Sarovar is constructed on river Narmada.
13. Tamil Nadu is the only state where all the houses have rooftop rain water structure
14. he world’s longest dam is Hirakud dam on river Mahanadi in Orissa.
14. In Rajasthan, rain water harvesting is known as Johads.
13. Bamboo drip irrigation is common in Meghalaya.
EXPLANATION:
(1) they provide for irrigation
(2) they help to generate hydro-electric power,
(3) they control floods,
(4) they prevent soil erosion,
(5) they help to develop fisheries,
(6) they provide inland navigation
(7) they provide water for industries,
(8) they provide recreational facilities and water for domestic use and
(9) they also help afforestation.
In India there are 162 major and 240 medium size and 74 small size river valley projects.
1. Damodar River Valley Project: This was the first multipurpose project constructed after Independence. It was a joint venture of former Bihar and West Bengal states. River Damodar rises in the Chotanagpur plateau of Jharkhand. But its floods caused a lot of destruction in West Bengal. It was called the “Sorrow of Bengal”. The objectives of this project were to control floods, provide navigation, hydro-electricity, fish culture, recreational facilities afforestation and prevention of soil erosion. It has 2,495 km. length of canals and 4.5 lakh hectares of land under irrigation. Dams are constructed across river Damodar and its tributaries at Tilaya, Konar, Maithon and Panchet hill. Thermal power stations are constructed at Bokaro, Chandrapur and Durgapur. Jharkhand and West Bengal benefit from this project.
2. Bhakra-Nangal Project: It is the highest multi-purpose river valley project of India. It is a joint venture of Punjab, Haryana and Rajasthan. Dams are constructed across the river Sutlej in Himachal Pradesh at Bhakra and Nangal. Bhakra dam is 226 mts. high and is the highest dam in Asia. The canals of this project are 3,402 kms. long and provide irrigation to 14.6 lakh hectares of land. Delhi and Himachal Pradesh also get irrigation water and hydro-electric power. The reservoir which is created is called ‘Govind Sagar’.
There are some projects which are meant only for the generation of power. The largest hydro-electric potential is along the Himalayas from Kashmir to Arunachal Pradesh. The snowfed and rainfed rivers have plenty of water. The relief features of this area are quite suitable for the generation of power. The second region is along the Western Ghats. This region gets heavy rainfall and it has rugged relief. The plateaus of peninsular India also have favourable relief and wherever water is sufficient, hydel power is generated. The prominent hydel power generating stations are Sileru in Andhra Pradesh, Dhuvaran in Gujarat, Shabarigiri and Idukki in Kerala, Koyna in Maharashtra and Sharavathi, Chakra and Kalinadi projects in Karnataka.
Q. State any four features of water resources available in India.
Ans. In the world only 3 per cent of total water is fresh water. It is available as surface water, ground water and brackish water from lagoons and backwaters.
(i) India accounts for about 4 per cent of the world’s water resources
(ii) The total water available from precipitation in the country in a year is about 4,000 cubic km.
(iii) The availability from surface water and replenishable ground water is 1,869 cubic km.
(iv) Out of this only 60 per cent can be put to beneficial uses.
(v) Thus, the total utilisable water resource in the country is only 1,122 cubic km.
Q. Describe the features of surface water distribution in India.
Ans. There are four major sources of surface water. These are rivers, lakes, ponds, and tanks.
a. In the country, there are about 10,360 rivers and their tributaries longer than 1.6 km each.
b. The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km.
c. However, due to topographical, hydrological and other constraints, only 32 per cent of the available surface water can be utilised.
d. The Ganga, the Brahmaputra and the Indus River accounts for 60 % of the total water resource in India. They have large water resource because size of catchment area or river basin is large and rainfall is high.
Q. Describe the features of ground water distribution in India.
Ans. Groundwater resources in the country are about 432 cubic km.
1. The Ganga and the Brahmaputra basins have about large (46 per cent of the total) replenishable groundwater resources.
2. The level of groundwater utilisation is relatively high in the river basins lying in northwestern region and parts of south India.
3. The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu.
4. However, there are States like Chhattisgarh, Orissa, Kerala, etc., which utilize only a small proportion of their groundwater potentials.
5. States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra are utilising their ground water resources at a moderate rate.S u r y a v e n g h
Q. Name the three states which have large surface water resources in lagoons and brackish lakes. For what purposes these water bodies are used?
Ans. India has a vast coastline and the coast is very indented in some states. Due to this, a number of lagoons and lakes have formed.
1. The States like Kerala, Orissa and West Bengal have vast surface water resources in these lagoons and lakes. Although, water is generally brackish in these water-bodies, it is used for fishing and irrigating certain varieties of paddy crops, coconut, etc.
Q. State important uses of water resources in India.
Ans. Water resources are used for:
a. India’s water demand at present is dominated by irrigational needs.
b. Agriculture accounts for most of the surface and ground water utilisation, it accounts for 89 per cent of the surface water and 92 per cent of the Ground water utilisation.
c. While the share of industrial sector is limited to 2 per cent of the surface water utilisation and 5 per cent of the ground-water,
d. The share of domestic sector is higher (9 per cent) in surface water utilisation as compared to groundwater.
e. However, in future, with development, the shares of industrial and domestic sectors in the country are likely to increase.
Q. Why the demand of water for irrigation is high in India.
Ans. Major Use of water is for irrigation in India. It is due to following reasons:
1. India is located in the tropical and sub-tropical region; therefore evapotranspiration is high. As such the demand of water by crops is high.
2. Spatial distribution of rainfall is uneven. Most parts of India such as north-west and Deccan plateau remain dry due to deficient rainfall. It becomes very difficult to practice agriculture without irrigation.
3. Seasonal distribution of rainfall is uneven. Rainfall is concentrated only in a few months therefore in most of the months irrigation is required.
4. Rainfall is highly variable and uncertain. There are breaks in the monsoon therefore even in areas of sufficient rainfall such as West Bengal and Bihar, irrigation is required.
5. Water requirements of certain crops such as jute, sugarcane, rice, is very high therefore the demand can be fulfilled by irrigation.
6. Use of high yielding seeds and fertilizers in the fields have made irrigation essential.
7. Agriculture productivity can be increased by assured irrigation therefore the demand for irrigation is high in India.
8. Provision of irrigation makes multiple cropping possible.
Ans. In the states of Punjab, Haryana and Western Uttar Pradesh irrigated areas are highest in India. It is because:S u r y a v e e r S i n g h
a. Wheat and rice crops are grown mainly with the help of irrigation in these states.
b. These states irrigates with the help of wells and tube-wells.
c. These states utilise large proportion of their ground water potential.
Ans. The four states are: Punjab, Haryana, Gujarat and Rajasthan.
Ans. The over-use of ground water resources in dry and drought prone areas has led to:
a. Decline in ground water table in Rajasthan and Gujarat.
b. Increased fluoride concentration in ground-water due to over withdrawal in Maharashtra and Rajasthan.
c. Increase in concentration of arsenic in West Bengal and Bihar.
d. Increased salinity in the soil in Punjab and Haryana.
Ans. The main reasons are:
i. Large and growing population: Water scarcity in cities is an outcome of large and growing population. It means more water for domestic use and also to produce more food. To achieve higher food-grain production, more irrigation is required. Thus high irrigation means over-exploitation of ground water resources.
ii. Industrialization: The growing number of industries in the country has put pressure on existing freshwater resources. Industries require large amount of water and also require electric power to run them. Much of this energy comes from hydroelectric power through dams which affects natural flow of water.
iii. Urbanization: Multiplying urban centres with large and dense populations and urban lifestyles need more water and energy requirements. The housing societies or colonies in the cities have their own groundwater pumping devices to meet their water needs. Thus the water resources are being overexploited and have caused their depletion in several of these cities.
iv. Poor quality of water: This scarcity may be due to bad quality of water. Much of it may be polluted by domestic and industrial wastes, chemicals, pesticides and fertilisers used in agriculture, thus, making it hazardous for human use.
Q. Why the conservation and management of our water resources is needed?
Ans. The conservation and management of our water resources is necessary for:
i. To safeguard ourselves from health hazards,
ii. To ensure food security, continuation of our livelihoods and productive activities
iii. To prevent degradation of our natural ecosystems.
iv. Over exploitation and mismanagement of water resources will deplete water resource and cause ecological crisis.
Q. State the main objectives of traditional dams.
Ans. Dams were traditionally built to stop rainwater and to impound rivers to provide water for irrigating the fields.
Ans. Dams were built under integrated water resources management approach which means that they has many uses of impounded water which are integrated with one another.-
i. Dams were traditionally built to impound rivers and rainwater that could be used to irrigate agricultural fields.
ii. Dams are also built for electricity generation,
iii. For water supply for domestic and industrial uses,
iv. For controlling floods,
v. For the purpose of recreation,
vi. For inland navigation and
vii. For fish breeding.
Q.Why did Jawaharlal Nehru proclaimed the dams as the temples of modern India?
Ans. The reason he proclaimed them as temples are:
i. Dams would integrate development of each sector of the economy.
ii. Dams were thought of as the vehicle that would lead the nation to development and progress,
iii. They would develop agriculture and the village economy
iv. They would develop industries.
v. They would help in the growth of the urban economy.
i). Irrigation has changed the cropping pattern of many regions with farmers shifting to water intensive crops. This has lead to the salinisation of the soil.
ii). Regulating and damming of rivers affect the natural flow of rivers causing poor sediment flow.
iii). Due to the dams, the flood plains are deprived of silt.
iv). Multipurpose projects induce pollution which leads to land degradation.
Q. Why the Multi-purpose projects and large dams have come under great opposition?
Ans. The reasons are:
a. Affect natural flow of running water:
i. Hence, it causes excessive sedimentation at the bottom of the reservoir.
ii. It results in rockier stream beds.
iii. They also fragment rivers making it difficult for aquatic fauna to migrate, especially for breeding.
b. Affect natural vegetation and soil:
i. The reservoirs that are created on the floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.
ii. The flood plains are deprived of silt, a natural fe
rtiliser, further adding on to the problem of land degradation.
c. Cause of many social movements:
i. They have been a cause of many new social movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.
d. Displacement of people:
i. They results in the large-scale displacement of local communities.
ii. Local people often had to give up their land, livelihood for the nation.
iii. The local people are not benefiting from such projects.
e. Change in cropping pattern:
i. Availability of irrigation has also changed the cropping pattern.
ii. Farmers have shifted to water intensive and commercial crops.
iii. This has great ecological consequences like salinisation of the soil.
iv. It has increased the social gap between the richer landowners and the landless poor.
f. Create conflicts:
i. The dams create conflicts between people wanting different uses and benefits from the same water resources.
ii. Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose project.
g. Failure to control flood:
i. The dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir and at the time of excessive rainfall.
ii. It was also observed that the multi-purpose projects induced earthquakes,
Q. Describe how the modern rainwater harvesting carried out.
Ans. The modern rainwater harvesting is done as:
a. Roof top rain water is collected using a PVC pipe.
b. It is filtered using sand and bricks.
c. Underground pipe takes this water to sump for immediate usage.
d. Excess water from the sump is taken to the we
e. Water from the well recharges the underground.
f. Later this water is taken out from the well during summer or dry season.
1. Rainfall in
also within the regions.
2. Rivers are flooded in the regions of heavy rainfall & cause huge loss of life & property.
4.
fluctuations in the flow of river water form season to season at uneven rate.
Q. Give examples of traditional water harvesting systems developed in ancient India.
Ans. In ancient India, people had in-depth knowledge of rainfall regimes and soil types. Thus they developed many techniques to harvest rainwater.
a. In hill and mountainous regions, people built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture. A kul leads to a circular village tank from which water is released as and when required.
b. ‘Rooftop rain water harvesting’ was commonly practised to store drinking water, particularly in Rajasthan.
c. In the flood plains of Bengal , people developed inundation channels to irrigate their fields.
d. In arid and semi-arid regions , agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil like the ‘khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan.
Ans. In semi-arid regions of Rajasthan traditional rainwater harvesting is carried out as:
a. Almost all the houses traditionally had underground tanks or tankas for storing drinking water.
b. The tanks could be as large as a big room;
c. One household in Phalodi had a tank that was 6.1 metres deep, 4.27 metres long and 2.44 metres wide.
d. The tankas were part of the well-developed rooftop rainwater harvesting system.
e. They were built inside the main house or the courtyard.
f. They were connected to the sloping roofs of the houses through a pipe.
g. Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’.
h. The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected.
i. The rainwater can be stored in the tankas till the next rainfall making it an extremely reliable source of drinking water when all other sources are dried up, particularly in the summers.
j. Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool.
Q. State the factors responsible for the bad quality of water.
i). Pollution of waterbodies by discharge of industrial effluents.
ii) . Use of fertilizers, pesticides in agricultural effluents.
Q. Which river is known as River of sorrow? Why?
Ans. River Damodar is known as Sorrow of Bengal for its fury of floods.
Q. Why are multipurpose projects developed after independence?
Ans. Multipurpose projects have been developed after Independence with the objective of integrated water resource management approach that would lead to the development of the nations.
Q. How is fresh water obtained?
Ans. The fresh water id obtained from precipitation, surface run off and ground water that is continually being renewed and recharged through the hydrological cycle.
Q. What is water scarcity? Mention any four factors responsible for water scarcity.
Ans. Storage of water is compared to its demand is knows as water scarcity.
Factors responsible:-
i ). Overexploitation of water resources.
ii). Improper management.
iii). Unequal access of water among different social groups.iv). Industrialization and urbanization.
Q. “Overpopulation or large and growing population can lead to water scarcity.” Explain.
i ). More population means more demand for water.
ii). A large population means more water not only for domestic use but also to produce more food.
iii). To facilitate higher food grain production, water resources are being overexploited to expand the irrigated areas and dry season agriculture.
iv). Overutilization of water results in lowering of the groundwater levels.
Q. How is industrialization responsible for water scarcity? Explain.
i). The ever increasing number of industries has made matter worse by exerting pressure on the existing freshwater resources.ii). Industries need power which is produced from water. The power is produced by the multi-purpose projects.
iii). Industries are also responsible for making water hazardous for human use.
Q. How had the growing population, industrialization and urbanization lead to water scarcity? Explain.
i). Growing population:- Growing population is one of the basic factors which is responsible for the scarcity of water. Most of our cities are facing this problem due to overpopulation. A large population means more water not only for domestic use but also to produce more food.ii). Commercialization of agriculture:- After the success of green revolution, our farmers are producing commercial crops. The commercial crops need more water and other inputs. Assured means of irrigation like tubewells and wells are responsible for the falling groundwater levels.
iii). Industrialization :- The post independent India witnessed intensive industrialization and urbanization. Today, large industrial houses are common in the form of industrial units of many MNCs. The ever increasing number of industries has made matters worse by exerting pressure on the existing freshwater resources.
iv). Urbanization :- Urbanization has also aggravated the problem of water scarcity. Most of our cities are over-populated. Overpopulation leads to over utilization of the water resources, and also pollutes the existing resources.
Q. Why is there a need to conserve water resources?
i). Water is necessary for life on earth. It is believed that life first originated in water before in invaded land. Water is in fact a pre-condition of life.
ii). Cultivation of crops depends on the availability of water. Water dissolves minerals and other nutrients in the ground. The roots of the plants draw this nutritious water from the soil. India is an agricultural country, so availability of water is a must.
iii) . Water is also important for industry. Its main function is for cooling.
iv). Water is also used for drinking and domestic consumption. The growing urbanization with its modern lifestyle has been demanding a greater share of water day by day.
Q. Distinguish between a dam and a multipurpose project.
Dam.
i). A dam is a barrier across the flowing water that obstructs, dissects or retards the flow, often creating a reservoir lake or an impoundment.
ii). It is a traditional concept.
Multipurpose project
i). A multipurpose project is that which fulfils a variety of purposes at the same time, for example irrigation generation of electricity, flood control, fish breeding, soil conservation, etc.
ii). It is a modern concept.
Q. Why multipurpose river valley projects are called the new temples of Modern India?
i).Generation of power (electricity) :- These multipurpose projects are the main source of power generation. They provide us neat, pollution free and cheapest energy which is the backbone of industry and agriculture.
ii) Flood Control:- These projects control the floods because water can be stored in them. These projects have converted many rivers of sorrows into rivers of boon.
iii). Soil conservation:- These conserve the soil because they slow down the speed of water.
iv). Irrigation :- These projects are the main source of irrigation for our country. These irrigate the fields during the dry seasons. Many perennial canals have been dug and they irrigate dry areas.
Q. How may the multipurpose river projects become harmful for the country? Explain with four examples.
i). Adverse effect on the fertility of the soil:- Due to construction of dams, there are no annual floods in the river. And because of this, the soil of the downstream region does not get nutrient rich silt. This decreases the fertility of the soil.
ii). Adverse impact on aquatic life:- Due to construction of dams on the rivers, the fish in the downstream area do not get sufficient nutrients material. Regulating and damming of rivers affect the natural flow of water causing poor sediment flow of downward, and excessive sedimentation at the bottom of reservoir. Dams also fragment rivers making it difficult for aquatic fauna to migrate for spawning i.e., to produce eggs.
iii ) Displacement of local communities:- The building of large dams results in displacement of local communities. The local people often have to give up their land and livelihood and their meagre (scant in amount) access and control over resources for the greater food of the nation.
iv) Change in the cropping pattern:- Multipurpose projects are responsible for providing assured means of irrigation to farmers. Due to this, most of farmers have changed the cropping pattern shifting to water intensive and commercial crops. This has lead to salinisation of soil leading to ecological imbalance.
Q. Write a short note on Narmada Bachao Andolan.
Narmada Bachao Andolan is a movement initiated by environmentalists, farmers, tribal people and human rights activists against the construction of Sardar Sarovar Dam on Narmada river in Gujarat. It has become a controversial issue due to the problems in the form of displacement of local people, loss of livelihood, floods, deforestation, etc.
Q. Distinguish between Surface water and ground water.
Surface Water
i). Water available on the earth’s surface in the form of river, streams, lakes and ponds.
ii). Quantity of surface water varies from time to time and from place to place as it s prone to evaporation and depends on rainfall.
iii). It is most easily available water which can be used for irrigation, power generation, navigation etc.
Ground Water
i). . Water seeped through the permeable rocks and is accumulated over a period of time.
ii). This water remains as a store house as it is not prone to evaporation.
iii). Groundwater is tapped through wells and tubewells or springs and can be used for irrigation, domestic and industrial purposes.
Q. Define the term rainwater harvesting. State any five objectives of rainwater harvesting.
Ans. Rainwater harvesting is a technique of increasing the recharge of groundwater by capturing and storing rainwater by constructing structures, such as dug wells, percolation pits, checkdams.
The objectives of rainwater harvesting are:-1. To meet the increasing demand.
2 . To reduce run-off.
3. To avoid flooding of roads.
4. To raise groundwater level.
5 .To improve the quality of groundwater.
Q. Discuss how rainwater harvesting in semi-arid and arid regions of Rajasthan is carried out.
Ans. In Semi-arid regions of Rajasthan every house had underground tankas to store the water for drinking purposes. These tankas are large and deep 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 a pipe and stored in the underground tankas. The rainwater collected, is stored in the tankas providing drinking water till the neat rainy season, when all other sources are dried up, these tankas were beneficial to beat the summer heat as they keep the rooms cool. The rainwater or palar pani as commonly known in these parts is considered the purest form of natural water.
Q. Mawsynram is the region of highest rainfall, yet it faces acute shortage of water. Why?
Mawsynram faces acute shortage of water as the rainwater harvested is inadequate to meet the needs of the people.
Q. What is rain water harvesting? Also state some of its importance.
Ans. Rain water harvesting is a method to capture and store rainwater for various uses. It is also used to recharge groundwater aquifers. It is a low cost and eco-friendly technique for preserving every drop of water by guiding the rain water to bore well, pits and wells.
Its importance can be judged by following facts that:
a. Rainwater harvesting increases water availability especially during the summer season and helps in bridging demand-supply gap.
b. Checks the declining ground water table by reducing dependence on ground water.
c. It saves energy to pump groundwater as recharge leads to rise in groundwater table.
d. Improves the quality of groundwater through dilution of contaminants like fluoride and nitrates,
e. Prevents soil erosion and flooding
f. Arrests salt water intrusion in coastal areas if used to recharge aquifers.
Ans. Water resources in India face many problems such as problem of availability, quality, use, and management.
1. Problems of availability:
a. Water resources are in excess in some regions such as in West Bengal whereas it is deficit in others such as Rajasthan and peninsular India.
b. Per capita availability of water is low in India. Water supply varies with seasons.
2. Problems of quality:
a. All the major source of water resources suffer from the problem of pollution. Water pollution is caused by domestic wastewater, industrial wastewater, and effluents and chemicals used in agriculture.
b. The Ganga and the Yamuna are the two highly polluted rivers in the country.
Ans. The quality of the surface water and ground water decreases due to:
1. Foreign matters such as micro-organisms, chemicals, industrial and other wastes.
2. Discharge of domestic and industrial wastewater from cities and towns without treatment in rivers and lakes.
3. Excessive use of fertilizers, insecticides, and pesticides in agricultural fields.
4. Seepage of these pollutants underground.
Ans. It is felt by many people that water conservation and management is necessary in India due to following reasons:
a. The availability of fresh water in many parts of our country is declining and these areas faces shortage of water.
b. Water resources are unevenly distributed in India.
c. The demand of water is growing rapidly but its quality is getting lower by the human activities.y a v e d. Water available from sea/ocean is negligible due to high cost of de-salinisation. Under such view conservation of water is necessary.
Ans. The availability of water resources of India can be increased and conserved by:
a. Collecting rainwater and stopping it from draining off (rainwater harvesting).
b. Scientifically managing the water resource of all river watersheds (watershed development).
c. Keeping water resource unpolluted by treating the wastewater from cities and industries.
d. Encouraging recycling and reuse of water for long run.
e. Ocean/sea water can be de-salinised by RO systems.
f. Transfer of water from water surplus areas to water deficit areas through inter linking of rivers.
Q. Name the most polluted rivers of India. Explain the causes of water pollution in these rivers and also mention how it can be prevented?
Ans. The most polluted rivers are:
a. The Yamuna River is the most polluted river in the country between Delhi and Etawah.
b. Other severely polluted rivers are:
i. the Sabarmati at Ahmedabad,
ii. the Gomti at Lucknow,
iii. the Kali, the Adyar, the Vaigai at Madurai
iv. The Ganga at Kanpur and Varanasi.
Water pollution in these rivers is caused by:
a. The intensive use of river water for irrigation, drinking, domestic and industrial purposes.
b. The drains carrying agricultural (fertilisers and insecticides), domestic (solid and liquid wastes), and industrial effluents.
c. The Low flow of water during the summer season.
d. The Organic and bacterial contaminations.
The water pollution in these rivers can be prevented by:
a. The legislative provisions such as the Water Acts and Environment Protection Acts which must be implemented effectively.
b. Generating public awareness and action about importance of water and impacts of water pollution.
Ans. The availability of water can be increased by recycle and reuse.
a. Use of low-quality water (such as recycled waste-water) for industrial purposes and fire fighting to reduce their water cost.
b. Similarly, in urban areas water after bathing and washing utensils can be used for gardening. Water used for washing vehicle can also be used for gardening. This would conserve fresh water for drinking purposes.
Q. What is watershed management? What are the important components of watershed management?
Ans. Watershed management basically refers to efficient management and conservation of all resources – natural or human within a watershed.
Its components are:
a. To prevent runoff of rainwater
b. To store and recharge groundwater through various methods like percolation tanks, recharge wells, etc.
Some examples of watershed management are:
a. Haryali is a watershed development project sponsored by the Central Government which aims at enabling the rural population to conserve water for drinking, irrigation, fisheries and afforestation. The Project is being executed by Gram Panchayats with people’s participation.
b. Neeru-Meeru (Water and You) programme (in Andhra Pradesh) and Arvary Pani Sansad (in Alwar, Rajasthan) have taken up constructions of various waterharvesting structures such as percolation tanks, dug out ponds (Johad), check dams, etc. through people’s participation.
c. Watershed development projects in some areas have been successful in rejuvenating environment and economy
Q. What is the percentage of fresh water on the earth surface?
Only 3% of the waterpresent onearth surface can be termed as fresh water resource.
Q. Why are the Great Plains of India rich in ground water resources?
The great plains of India arerich in ground water becauseof thelarge scale deposition of alluvial soil. Water percolates easily in the alluvial soils and hencepotentiality ofground water development is high in the great plains of India. The soft sedimentary rocks easily seep surface water.
Q. What is Haryali?
Haryali is a watershed development project sponsored by the central government which aims at enabling the rural population to conserve water for drinking, irrigation, fisheries and afforestation. The project is being executed by Gram Panchayat with people’s participation.
Q. Name four major rivers of North India.
Four major rivers of North India are
- The Indus river
- The Ganga river
- The Brahmaputra river
- The Yamuna river
These rivers carry about 60% of the total surface water of India.
Q. What are the main sources of irrigation?
The main sources of irrigation are:
1. Canals
2. Wells and Tube Wells
3. Tanks
Q. Why is the share of agricultural sector in total water used expected to decline in the country?
The share of agricultural sector in total water used in the country is expected to decline because:
- The industrial and domestic sectors in the country are likely to increase.
- The total utilizable water resources are also declining.
- The overuse of ground water resources has led to decline in the groundwater.
Q. What factors are responsible for highest groundwater utilization in the states of Punjab, Haryana, and Tamil Nadu?
The ground water utilization is very high in the states of Punjab, Haryana and Tamil Nadu. These states are advanced agricultural states. Water is used mainly in irrigation. The share of agriculture sector in total water utilization is much higher than other sectors.
Q. Describe the main methods of conserving water resources.
The main methods of conserving water resources are:
1. Water of oceans, rivers and lakes should not be polluted.
2. It should be saved from urban waste and chemicals of industries.
3. Dams should be built across the rivers and lakes to store water in reservoirs.
Q. What are the factors that are responsible for increasing the demand for irrigation?
Factors that are responsible for increasing the demand for irrigation are:
1. Tropical and Subtropical Climate: Major part of India is located in tropical and sub-tropical region where there is high rate of evapotranspiration. And thus irrigation is required to
supplement the natural supply of water to crops.
2. Uneven Spatial Distribution of Rainfall: Monsoonal rainfall is very uneven and thus in rain deficit areas irrigation facilities are required.
3. Uneven Temporal Distribution of Rainfall: The temporal distribution of rainfall is also uneven. Rainfall is confinedto a very short period of time and thus in rest of the months irrigation facilities are required.
4. High Rainfall Variability: A large part of India suffers from high rainfall variability and thus floods and droughts with in the same period in different parts of the India is very common. Without irrigation, agriculture in India is reduced to a gamble in the hands of monsoons.
5. Nature of Crops: The nature of certain crops is such that they require large quantities of water for their growth.
6. High Yielding Crops: The main element of the Green Revolution is high yielding crops which require regular moisture to increase farm production.
7. Long Growing Period: India has long growing period which extends throughout the year and thus irrigation facilities are important to provide water to the crops throughout the year.
8. Increase in Productivity: Productivity of agriculture is higher on irrigated land than on unirrigated land. Therefore extending irrigation facilities can increase production and productivity of crops.
Q. Depleting water resources may lead to social conflicts and disputes. Elaborate it with suitable examples.
The available water is rapidly depleting. The depletion of water resources leads to many social conflicts and disputes in the country. Some of the major disputes are:
1. The Krishna - Godavari waters dispute among Maharashtra, Karnataka, Andhra Pradesh and Orissa.
2. The Cauvery water dispute among Tamil Nadu, Karnataka and Kerala.
3. The Narmada water dispute among Gujarat, MP, Maharashtra and Rajasthan.
4. The Tungabhadra project issues other than the high level canal between Karnataka and Andhra Pradesh.
5. The issue of extension of irrigation from the Rangwan Dam of UP between UP and MP.
6. The Koymani river dispute between Bihar and West Bengal.
7. The dispute over the Keolari Nadi waters between MP and UP.
8. The Bandar Canal project, affecting Madhya Pradesh and Uttar Pradesh.
Q. Differentiate between Surface water and Ground water.
| Surface Water | Ground Water |
| 1. It includes rivers, lakes, canals etc. and is found on the land surface. | 1. It includes wells and tube wells. The water is drawn from below the surface. |
| 2. Seasons have less effect on the surface water. | 2. The water table increases in the rainy season and decreases in the dry season. |
| 3. Running and falling water is used in irrigation, and power generation. | 3. Ground water is used generally for domesticpurposes and irrigation. |
| 4. Rivers are major sources of surface water. Total run off among all rivers is estimated to be 1869 bcm. | 4. Out of the total ground water available only 37.23 has been developed in India. |
| 5. The amount of surface waterdepends upon the amount of rainfall. | 5. The amount of ground water depends on the amount of rain water and the permeability of rocks. |
Q. Mention any five differences between North Indian rivers and Peninsular Rivers in terms of their hydrological characteristics.
| North Indian Rivers | Penin sular Rivers |
| 1.The catchment areas and basins of the North Indianrivers are very large. | 1. The catchment areas and basins of the Peninsular rivers are comparatively smaller in size. |
| 2. The northern rivers originate from the snow covered areas and receive water from rainfall as well as from snow melt. Therefore, they are perennial. | 2. The peninsular rivers depend entirely on rainwater and are seasonal. |
| 3. The northern rivers ha ve deep gorges. | 3. The peninsular rivers flow in shallow valleys. |
| 4. The northern rivers form river meanders and often change their course. | 4. The peninsular rivers follow more or less a straight course and do not change it. |
| 5. These rivers aresuitable for navigation. | 5. These rivers are not much suited for navigation. |
Q. What are the major problems regarding water resources?
The main problems that are related towater resources are:
- Problem of Availability: Water resources are in excess in certain regions and deficit in others. The north eastern states of the country have excess water resources. On the other hand, dry areas of Rajasthan face acute shortage of water. Rainfall is concentrated in a short period of rainy season and the major part of the year remains dry.
- Problem of Utilisation: About 90% of the towns are provided with potable water, the quality and quantity of water is much below norms. Slums and squatter settlements are practically without any water supply. Rural areas are much worse off with respect to supply of potable water. Incase of irrigation also the picture is not bright. Although 68% of the total ultimate irrigation potential has already been developed, yet about two-thirds of the cropped area is rain-fed. Another problem is the low efficiency of water use.
- Problem of Quality: Quality of water is largely deteriorating throughout the country. It has been estimated that about three-fourths of the surface water in India is polluted. Most of the riversin Indiaare polluted. In fact the water bodies nowadays are treated asdumping grounds. Dumping of all sorts of waste matter that includes industrial waste, municipal waste, and residue of chemical fertilizers into our rivers isa common practice.
Q. Explain Watershed management and how does it play an important role in sustainable development?
Watershed is defined as a geohydrological unit draining to a common point by a system of drains. All lands on earth are part of onewatershed or another. Watershed is thus the land and water area, which contributes runoff to a common point. In other words watershed is a topographically delineated area draining into a single channel.
Watershed Management
Watershed management has emerged as a permanent solution for water scarcity. Watershed management refers to efficient management and conservation of water resources. The permanent solution to attain “water prosperity” for our land lies in the adoption of watershed management practices by our farming community.
Three main components in watershed management are:
1. Land Management
2. Water Management
3. Biomass Management
Watershed management plays an important role in sustainable development:
- It involves prevention of runoff and storage and recharge of groundwater.
- Watershed management includes conservation and judicious use of all resources.
- It aims at bringing about balance between natural resources onone hand and society on the other.
Watershed development projects in some areas have been successful in rejuvenating environment and economy.
Q. What is the distribution of irrigated area in India?
There is a large scale variation in the distribution of the irr
igated area. It varies from 6.4% in Mizoram to about 91% in Punjab. On the basis of the distribution of irrigated areas among the states we can categorize the statesas follows:
- States with High Proportion of Irrigated Area: Areas with more than 40% of net irrigated area are called areas of high proportion of irrigated area. Punjab is the state having highest percentage of land under irrigation that is 91%, followed by Haryana (85%). Other states in this category are: Uttar Pradesh, Bihar, Jammu and Kashmir, Tamil Nadu, Andhra Pradesh and Manipur.
- States with Moderate Proportion of Irrigated Area: States with moderate proportion (30-40%) of net irrigated area form a continuous belt, extending from Rajasthan in the west to West Bengal in the east.
- States with Low proportion of Irrigated Area: States with low (20-30%) and very low (less than 20%) proportion of net irrigated area encompasses all the north eastern states.
Q. Explain Watershed management and how does it play an important role in sustainable development?
Watershed is defined as a geohydrological unit draining to a common point by a system of drains. All lands on earth are part of onewatershed or another. Watershed is thus the land and water area, which contributes runoff to a common point. In other words watershed is a topographically delineated area draining into a single channel.
Watershed Management
Watershed management has emerged as a permanent solution for water scarcity. Watershed management refers to efficient management and conservation of water resources. The permanent solution to attain “water prosperity” for our land lies in the adoption of watershed management practices by our farming community.
Three main components in watershed management are:
1. Land Management
2. Water Management
3. Biomass Management
Watershed management plays an important role in sustainable development:
- It involves prevention of runoff and storage and recharge of groundwater.
- Watershed management includes conservation and judicious use of all resources.
- It aims at bringing about balance between natural resources onone hand and society on the other.
Watershed development projects in some areas have been successful in rejuvenating environment and economy.
RAIN WATER HARVESTING: In simple language, Rain Water Harvesting is the principle of collecting and using precipitation from a catchments surface. Rain water harvesting is a method to capture and store rain water for various uses. It is also used to recharge groundwater. Any man-made scheme or facility that adds water to an aquifer may be considered to be an artificial recharge system.
RAIN WATER HARVESTING TECHNIQUES: The main techniques of rain water harvestings are:
- Harvesting through Watershed Management
- Harvesting through Lakes
- Harvesting through Service Wells
- Harvesting through Recharge Wells
IMPORTANCE OF RAIN WATER HARVESTING
Rain water harvesting is essential because:-
1. Surface water is inadequate to meet our demand and we have to depend on ground water.
2. Due to rapid urbanisation, infiltration of rain water into the sub-soil has decreased drastically and recharging of ground water has diminished.
It is possible that area may have ample water resource but still face water scarcity, which may be an outcome of
• Large and growing population.
• Consequent greater demands of water.
• Unequal access to it.
Three key features of India's National Water Policy,2002 are
1) Providing drinking water to all human beings and animals should be the first priority.
2) Measures should be taken to limit and regulate the exploitation of groundwater.
3) The efficiency of utilisation in all the diverse uses of water should be improved.
• Ensuring food security.
• Preventing degradation of natural ecosystems.
• Preventing ecological crisis.
• Safeguarding ourselves from health hazards.
• Continuation of our livelihoods.
Water scarcity has increased tremendously in the recent years due to various factors. One of the factors is industrialisation that causes waterscarcity in the following ways:
• Intensive industrialisation led to urbanisation.
• Multiplying urban centre’s with large and densepopulation has added to an increase in the demandof water and energy.
• Increase in industry exerts more pressure on existing freshwater resources.
1. Domestic consumption
2 comments:
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