Water Resources - Class 10 Geography - Extra Questions

 Water scarcity in most cases is caused by over- exploitation, excessive use and unequal access to water among different social groups.

Rainfall is the main source of fresh water in India. From precipitation alone (including snowfall), India receives 4,000 cubic km water. Of this, monsoon rainfall from June to September alone accounts for about 3,000 cubic km. A good part of it is lost through the process of evaporation and plant transpiration. A large part of water percolated into the ground and is available to us in the form of groundwater.

Rainwater harvesting is one of the most effective methods of water management and water conservation. It is the term used to indicate the collection and storage of rainwater used for human, animals and plant needs. It involves collection and storage of rainwater at a surface or in the subsurface aquifer before it is lost as surface runoff.

'Hydrological cycle' renews and recharges the fresh water which is quite essential for sustenance of wildlife and human being also.

A multipurpose project is that which simultaneously serves several purposes. A dam built across a river often serves more than one purpose at a time and is termed as a multipurpose project. Flood control, irrigation, hydroelectric generation, navigation, fishing and tourism etc are some of the chef aims of multipurpose project.   

Rainwater harvesting allows the collection of large amounts of water and mitigates the effects of drought. Most rooftops provide the necessary platform for collecting water. Rainwater is mostly free from harmful chemicals. Therefore, rainwater harvesting is must nowadays.

A multipurpose project is that which simultaneously serves several purposes. A dam built across a river often serves more than one purpose at a time and it is termed as a multipurpose project. It comes with some advantages at the same time some disadvantages. The advantages are flood control in flood-prone areas, irrigation facilities, hydroelectricity, check soil erosion etc. On the other hand, it has disadvantages such as, it restricts the natural flow of the river and the sediments are deposited in the river bed, it causes deforestation and disturbs the aqua life of the river.

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 Sutlej-Beas river basin, the Bhakra–Nangal project water is being used both for hydel power production and irrigation. 

Water is one of the most precious natural resources and a key element in the socio-economic development of a country. Rainfall is the main source of fresh water in India. From precipitation alone, India alone receives 4,000 cubic km of water. Of this, monsoon rainfall from June to September alone accounts for about 3,000 cubic km. A good part of it lost through the process of evaporation and plant transpiration. A large part of water percolates into the ground and is available to us as groundwater. So water is available in two different forms, viz, (1) surface water and (2) groundwater.

The water seeping in the ground during rainfall is available as underground water resource and this water is called ground water.

Traditional methods of rainwater harvesting like 'the rooftop method' are becoming popular in India.  In Gendathur, Mysore, 200 households have adopted the rooftop rainwater harvesting method thereby making the village rich in rain water. The state of Tamil Nadu has made it compulsory for all the houses to have rooftop rainwater harvesting structures. Defaulters are severely punished. 

Houses in the semi arid regions of Rajasthan have traditionally constructed tanks for storing drinking water. They are big and are a part of the well-developed rooftop rainwater harvesting system. The tanks are constructed inside the main house or the courtyard, and are connected to the sloping roofs of the houses through a pipe. The rain falling on the rooftop travels down and is stored in the tanks. The first spell of rain is not collected as this water cleans the roof and the pipes. The rainwater from the subsequent spells is collected. This water is used till the next rainy season, and is reliable source of water even after other sources have dried up. The tanks also help in cooling the houses as rooms built around them have generally low temperatures due to conduction. 

In recent years, multipurpose projects and large dams have come under great scrutiny and opposition. Many thought water harvesting system was a viable alternative, both socio-economically and environmentally.
From ancient period, people were well aware of the water harvesting system. They had in depth knowledge of rainfall regimes, soil types and wide ranging techniques to harvest rainwater, groundwater, river water and flood water.
Thus, water harvesting system is taken as a more viable alternative to dams because,
(i) like dams, it does not displace local people.
(ii) it does not cause environmental problems like loss of flora and fauna.
(iii) during rainy season, excess water is released from dams, which induces floods or create the flood situation, which is not so in the case of water harvesting.
(iv) the local people are not benefitting from big dams, it is the landlords, large farmers, industrialists and the urban centres who are benefitted. In water harvesting system, common people use the stored water for personal use and in agricultural field.

Now-a-days groundwater is highly overused because of many reasons, some of which are as follows.
(i) Groundwater is a fresh water source and can be used for drinking purpose. It is actually over exploited in urban areas for domestic use and drinking purpose.
(ii) Groundwater is extensively used for irrigation purpose, especially in North India. Here, most farmers have their own wells and tubewells in their farms for irrigation to increase their production.
(iii) Post-independent India witnessed intensive industrialization and urbanization. Both these factors have made the matter worse by exerting pressure on existing freshwater resources.
(iv) After toxication and pollution of rivers and many lakes by the increasing industrialization, groundwater becomes practically only source of freshwater used directly without treatment. Over exploitation and mismanagement of water resource may lead to ecological crisis which has an immense impact on our life.
(v) Large population implies that more water will be required not only for domestic use, but also for agricultural use to grow more food for the large population. 

Water is an important natural resource and is the very basis of our life. The best way to conserve water is by its judicious use. Following are some steps we can take to conserve water:

The scarcity of water is increasing day-by-day in India due to the following reasons.
(i) The rapidly growing population has Increased the demand for water used for drinking and domestic purposes. The rising demand of food and cash crops which require larger amount of water has reduced available water.
(ii) Water resources are being over-exploited about expanding Irrigated areas and also to meet the need for growing another crop in the dry season.
(iii) Industrialization has been increased and industrial processes require large amounts of water.

The main objectives of rainwater harvesting are :

 In ancient India rainwater harvesting developed in many ways They were:

(i) Well irrigation is still a popular means of irrigation because:

1. Surface wells can be constructed at a very low cost.

2. Wells can be used even during summers.

 (ii) Significance of rainwater harvesting are:

Many countries in the world today suffer from water scarcity. Rain water harvesting is required as this technique of storing water ensures water supply even during dry months or droughts. Besides this is an environmental friendly technique of storing water.

Two advantages of rainwater harvesting:
(i) Recharge of ground water.
(ii) Conservation of water reduces surface runoff.

Reasons for conservation of water resources:
(i) The overexploitation of underground water often results in the lowering of water table.
(ii) The growth of population has resulted in water scarcity.
(iii) Our water resources like the underground water, rivers, lakes, etc. are polluted.

Two objectives of rain water harvesting:
(i) To utilise the rainwater for domestic consumption. 
(ii) Raise ground water table.

The objectives of multipurpose projects are:
a. To provide water for irrigation for the nearby fields
b. To generate electricity
c. To supply water to industries.

(i) Biogas:- Biogas is produced by processing residual waste from livestock (dung, manure and uneaten food), food production (fruit and vegetable waste, residues from meat, fish and dairy processing, brewery waste, food waste and much more) and effluents from industrial as well as municipal wastewater treatment plants. By constructing biogas power plants, agriculture assumes an important contribution to supplying energy from renewable resources as well as to the disposal of organic wastes. Digestates are produced as a by-product of biogas manufacturing, which can in turn be used as high-quality digestate.

(ii) Roof top rain water harvesting:- A water harvesting system in which rain falling on a roof is led through connecting pipes into a ferro-cement water collecting jar.

The Gobindsagar Reservoir, named after Guru Gobind Singh, created by the Bhakra-Nangal dam across the river Sutlej, is the third largest reservoir in India.

Houses in the semi arid regions of Rajasthan have traditionally constructed tanks for storing drinking water. They are big and are a part of the well-developed rooftop rainwater harvesting system. The tanks are constructed inside the main house or the coutryard, and are connected to the sloping roofs of the houses through a pipe. The rain falling on the rooftop travels down and is stored in the tanks. The first spell of rain is not collected as this water cleans the roof and the pipes. The rainwater from the subsequent spells is collected. This water is used till the next rainy season, and is a reliable source of water even after other sources have dried up. The tanks also help in cooling the houses as rooms built around them have generally low temperatures due to conduction.

• Rainwater harvesting is the process of collecting the rainwater from the surfaces it falls and then collecting it for the use in the future.
• The advantages of rainwater harvesting are reducing pressure on groundwater, easy to maintain, reduces soil erosion, etc.
• Paar is a common water harvesting practice in the western Rajasthan region.
• Johads are small earthen check dams that capture and conserve rainwater, improving percolation and groundwater recharge. Practiced in Rajasthan, India.
  

i. It is the diagram of rooftop rainwater harvesting method.

The process by which rain water is collected and stored either to recharge the ground water or for use in the future is known as rainwater harvesting. The method or setup used for rainwater harvesting is known as rainwater harvesting system.
The rainwater on the roofs of the buildings is collected through canals that drain the water into ground reservoirs. This stored water is later utilized. 
They recharge the ground water. 
They can be used for drinking and other domestic purpose. 
Water can be used throughout the year. 
Reduce storm water discharges, urban floods and overloading of sewage treatment plants. 
Reduce seawater ingress in coastal areas. 
They act as water for irrigation. 

A multipurpose project is that which simultaneously serves several purposes such as irrigation, water storage etc. A dam built across a river often serves more than one purpose at a time and is termed as a multipurpose project. The objectives of Multi-purpose river valley projects are : (i) to control flood. (ii) check soil erosion.(iii) provide water for irrigation.

In India after independence, industries are increasing in a rapid Pace and have become a reason for pressure on existing fresh water resources. Fresh water is almost limited,though renewable in India, but over exploitation and mismanagement of this resource by industries are aggravating the water stress day-by-day.

Industries especially heavy industries use huge amount of freshwater for industrial purpose and pollute such water.

These industries for their energy consumption purpose depend on hydroelectric projects and this electricity is generated through damming the rivers upstream.

So the river almost dries in the lower stream areas.These Industries also contaminate the ground water through seepage of industrial wastes. Hence, the increasing number industries exert pressure on existing fresh water resources.

Rainwater harvesting is technology of harvesting water from rainwater which usually gets runoff otherwise. 

• Surface water- It is water found in a river, lake or other surface cavities.
  

Surface water is usually not very high in mineral content.
Surface water is called as soft water due to its less mineral content.

• Groundwater is water contained in or by a subsurface layer of soil or rock.

Groundwater commonly contains less contamination than surface water because the rock tends to act as a filter to remove some contaminants.
Due to the minerals picked up while filtering through the rocks, groundwater is typically considered to be hard water.

• Majority of the water resources are contaminated with the bio and chemical pollutants.Increased industrialization and construction activities, the changing climatic conditions are also the reasons for water scarcity in India.