CBSE Class 10 Geography Water Resources Worksheet Set A

Even though three-fourth of the world is covered with water and water is a renewable resource, yet countries and regions around the globe suffer from water scarcity. Why is it predicted that by 2025, nearly two billion people will live in absolute water scarcity? In recent times you would have heard about severe water crisis in the South African city of Cape Town.

Water: Some Facts and Figures

• Out of total volume of water on earth; 97.5% exists in oceans and seas.
• About 2.5% of total water is available as freshwater.
• 70% of total freshwater is present as frozen ice in icebergs and glaciers.
• A little less than 30% of total freshwater is stored as groundwater.
• India receives about 4% of global precipitation.
• India ranks 133rd in the world in terms of water availability per person per annum.
• The total renewable water resources in India are estimated at 1,897 sq km per annum.
• It is predicted that large parts of India will join regions with absolute water scarcity; by 2025.

WATER SCARCITY AND THE NEED FOR WATER CONSERVATION AND MANAGEMENT

Where is the water scarcity likely to occur? As you have read in the hydrological cycle, freshwater can be obtained directly from precipitation, surface run off and groundwater. Is it possible that an area or region may have ample water resources but is still facing water scarcity? Many of our cities are such examples.
- Large growing population leads to – greater demands for water for domestic use and to produce more food. Water resources are over-exploited to expand irrigated areas. Dryseason agriculture also uses water during the lean season. Indiscriminate pumping of water from tube wells leads to falling groundwater levels. This adversely affects water availability and food security of the people in the long run.
- The ever-increasing number of industries has made matters worse by exerting pressure on existing freshwater resources. Industries, apart from being heavy users of water, also require power to run them. Much of this energy comes from hydroelectric power. Today, in India hydroelectric power contributes approximately 13.5% of the total electricity produced ( as of 2017)
- Multiplying urban centers with large and dense populations and urban lifestyles have added to water and energy requirements and further aggravated the problem.
- Most housing societies or colonies in the cities, have their own groundwater pumping devices to meet their water needs. In most cases these are uncontrolled leading to depletion in ground water levels.
ff In addition to the quantitative aspect the qualitative aspect of water available to us is very important. This scarcity may be due to bad quality of water. Lately, there has been a growing concern that even if there is ample water to meet the needs of the people, much of it may be polluted by domestic and industrial wastes, chemicals, pesticides and fertilizers used in agriculture, thus, making it hazardous for human use.
India’s rivers, especially the smaller ones, have all turned into toxic streams. And even the big ones like the Ganga and Yamuna are far from being pure. The assault on India’s rivers – from population growth, agricultural modernization, urbanization and industrialization – is enormous and growing by the day. This entire life stands threatened.

Source: The Citizens’ Fifth Report, CSE, 1999.
- Large scale deforestation has disturbed the natural recharge of groundwater at many places. Construction of concrete buildings, factories and roads has also made the ground less impervious to rainwater. This has almost totally stopped the percolation of rainwater to recharge groundwater.
- Excess use of chemical fertilizers and insecticides has contaminated groundwater at many places. The contamination is at such a high level that water has become unfit for human consumption.
- Sewage and effluents are being discharged into rivers and ponds; without being treated. This has turned most of the rivers into filthy drains.

Water Resource Management

• Our archaeological and historical records show that from ancient times we have been constructing sophisticated hydraulic structures like dams built of stone rubble, reservoirs or lakes, embankments and canals for irrigation.
• Hydraulic Structures in Ancient India
• In the first century B.C., Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
• During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
• Evidences of sophisticated irrigation works have also been found in Kalinga, (Odisha),Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka), Kolhapur (Maharashtra), etc.
• In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time was built.
• In the 14th Century, the tank in Hauz Khas,Delhi was constructed by Iltutmish for supplying water to Siri Fort area.

MULTI-PURPOSE RIVER PROJECTS AND INTEGRATED WATER RESOURCES MANAGEMENT

- Dams were traditionally built to restrain rivers and store rainwater that could be used later to irrigate agricultural fields. Today, dams are built not just for irrigation but for electricity generation, water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding. Hence, dams are now referred to as multi-purpose projects where the many uses of the impounded water are integrated with one another.
- For example, in the Sutluj-Beas river basin, the Bhakra – Nangal project water is being used both for hydel power production and irrigation. Similarly, the Hirakud project in the Mahanadi basin integrates conservation of water with flood control.- Multi-purpose projects, launched after Independence with their integrated water resources management approach, were thought of as the vehicle that would lead the nation to development and progress, overcoming the handicap of its colonial past. Jawaharlal Nehru proudly proclaimed the dams as the ‘temples of modern India’; the reason being that it would integrate development of agriculture and the village economy with rapid industrialization and growth of the urban economy.

- A dam is a barrier across flowing water that obstructs, directs or retards the flow of the river often creating a reservoir, lake or impoundment.
- “Dam” refers to the reservoir rather than the structure. Most dams have a section called a spillway or weir over which or through which it is intended that water will flow either intermittently or continuously.
- Dams are classified according to structure, intended purpose or height. Based on structure and the materials used, dams are classified as timber dams, embankment dams or masonry dams, with several subtypes. ff According to the height, dams can be categorized as large dams and major dams or alternatively as low dams, medium height dams and high dams. 

RAINWATER HARVESTING

In ancient India, there existed an extraordinary tradition of water-harvesting systems. People knew about rainfall patterns and soil types and developed different techniques to harvest rainwater, groundwater, river water and flood water depending on the local ecological conditions and their water needs.

• In hill and mountainous regions, people-built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.
• ‘Rooftop rain water harvesting’ was commonly practiced to store drinking water, particularly in Rajasthan.
• In the flood plains of Bengal, people developed inundation channels to irrigate their fields.
• 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.- In dry regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, almost all the houses traditionally had underground tanks or tankas for storing drinking water. It was a part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard. They were connected to the sloping roofs of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’. Usually the first spell of rain was not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected. Rainwater was stored in the tankas till the next rainy season. These were a reliable source of drinking water when all other sources are dried up, particularly in the summers.
• Rainwater, or palar pani, as commonly referred to in these parts, is considered the purest form of natural water. Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool. Most of the rainwater just flows off without percolating down the ground. Waste of water can be prevented by using rainwater harvesting. Rainwater can be collected for future use or can be channelized to recharge groundwater. Rooftop rainwater harvesting is ideal to be applied at small scale. Many infrastructure projects; like Metro rail and flyovers have also started making provisions for rainwater harvesting. Roof top rain water harvesting is the most common practice in Shillong, Meghalaya. It is interesting because Cherapunjee and Mawsynram are just about 55 km from here and receive the highest rainfall in the world yet the state capital Shillong faces acute shortage of water. Nearly every household in the city has a roof top rain water harvesting structure. Nearly 15-25 per cent of the total water requirement of the household comes from roof top water harvesting.

Bamboo Drip irrigation System is also extensively used in Meghalaya.

- Tamil Nadu is the first 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.

•  Roof top rain water is collected using a PVC pipe
•  Filtered using sand and bricks
•  Underground pipe takes water to a tank for immediate usage
•  Excess water is taken to the well
•  Water from the well recharges the underground 

Question. Why are different water harvesting systems considered a viable alternative both socio-economically and environmentally in a country like India?
Answer : Keeping in view the disadvantages and rising resistance against the multi¬purpose projects, water harvesting system is considered a viable alternative both socio- economically and environmentally.
1. In ancient India also along with the sophisticated hydraulic structures, there existed an extraordinary tradition of various water harvesting systems.
2. People adopted different techniques in different areas. In hilly regions people built diversion channels like the ‘guls’ or “kuls’ for agriculture.
3. Roof-top rainwater harvesting was commonly practised to store drinking water, particularly in Rajasthan.
4. In the flood plains of Bengal, people developed inundation channels to irrigate their fields. Khadins, Johads and Tanks are the forms of rainwater harvesting practised in Rajasthan.

Question. Explain any three reasons responsible for water scarcity in India.
or
Water is available in abundance in India. Even then scarcity of water is experienced in major parts of the country. Explain it with four examples.
Answer : a. The availability of water resources varies over space and time, mainly due to the variations in seasonal and annual precipitation.
b. Over-exploitation, excessive use and unequal access to water among different social groups.
c. Water scarcity may be an outcome of large and growing population and consequent greater demands for water. A large population means more water to produce more food. Hence, to facilitate higher food-grain production, water resources are being over exploited to expand irrigated areas for dry-season agriculture.
d. Most farmers have their own wells and tubewells in their farms for irrigation to increase their production. But it may lead to falling groundwater levels, adversely affecting water availability and food security of the people. Thus, inspite of abundant water there is water scarcity.