Water Resources (Class 10 Geography Chapter 3 Notes)

Major Rivers and Dams of India/Images Source: NROER
Around 71% of the earth surface is covered with water, but only a tiny portion of water is fit for consumption. The freshwater is maintained by the hydrological cycle, also known as the water cycle. The water cycle makes the water a renewable resource. However, due to mindless human activities, the earth is now facing the acute water shortage.

Some facts and figures about Water
Oceans makes up 97.3% of total water. Only 2.7% is the total fresh water available. Out of which, ice-caps in Antartica hold 70% of world freshwater, groundwater stored in aquifers makes up 0.68% of total water, and rest of the freshwater less than 0.01% comes of freshwater lakes, rivers and ponds.

Water Resources
India receives 4% of global rainfall. It stands at the 133rd position in terms of water availability per person. Its total renewable water resources are estimated at 1897 sq km per annum. By 2025, it is predicted by the United Nations, a large part of India will join the regions having absolute water scarcity.

Water Scarcity and Need For Water Conservation
Water scarcity can be defined as the lack of access to safe and clean water as per need of population in a region. According to research, water stress happens when water availability is less 1600 cubic meter per person a year.

There are two types of factors behind water scarcity. These are quantitative and qualitative factors.

Quantitative Factors (Amount of Water Available)
1. Over-exploitation of water resource
2. Unequal access to water among different income or social groups
3. Large or over-population
4. Rapid and unsustainable industrialization

Qualitative Factors (Quality of Water Available)
1. Industrial and household water pollution (dumping of untreated sewage water into rivers, lakes and ponds).
2. Groundwater pollution (Use of excessive fertilizers which gets seeped into the earth by irrigation water).

Water Resources Management
India is known for sophisticated water resources management structures such as dams, reservoirs, lakes, and canals and we have continued this tradition in modern times.

Sringaverapura near Allahabad on the banks of Ganga, Bhopal lake, Hauz Khas (Delhi) are examples of historical water resources management structures in ancient India.

Dams
A dam is a barrier built across flowing water that obstructs, retards and directs water flow creating a reservoir or lake. However, in general term, a dam refers to both barrier and reservoir.

Dams are classified on the basis of their structure, purpose and height.
Structure: timber dams, masonry dams
Height: low dams, medium height dams, large dams
Purpose: irrigation water dams, multi-purpose dams

Multi-purpose Dam Projects
Modern dams are not only used for irrigation but several purposes. Thus, these dam projects are called multi-purpose dams. For example, the Bhakra-Nangal dam project on Satluj is used for supplying irrigation water and generating electricity. Hirakund Project on Mahanadi is used for water conservation and flood control.

Advantages of Multi-Purpose Dam Project
1. Electricity generation
2. Water supply
3. Flood control
4. Irrigation
5. Recreation
6. Inland navigation
7. Fish breeding

These dam projects transformed India growth and throttled the Indian economy in both rural and urban centres. Pandit Jawaharlal Nehru termed dams as temples of modern India.

Disadvantage of Multi-Purpose Dams

1. affects the natural flow of water and sediments
2. submerges a large section of flood plains, vegetation and soil
3. causes mass displacement of local communities, especially marginal farmers
4. change in the cropping pattern and loss of biodiversity
5. unable to stop floods in case of heavy rainfall and earthquakes
6. salinization of soil
7. land degradation in the lower course due to not revival of soil by new sediment deposits

Movements Against Multi-Purpose Dams and Water Management Projects
Sighting disadvantages of large dams, there are several protest movements are taken against them. Narmada Bachao Aandolan and Tehri Dam Aandolan are prime examples of this.

Inter-state disputes regarding water sharing have also become common. Krishna-Godavari dispute between Karnataka and Andhra Pradesh is one of the famous inter-state water resources management disputes.

Others major inter-state water disputes are Vansadhara water dispute between Andhra Pradesh and Odisha, Mahadayi Water Dispute between Goa, Karnataka and Maharashtra and Ravi and Beas water dispute among Punjab, Haryana and Rajasthan.

Even at intra-state levels, there is a constant tug of water over water resources among rural and urban centres. Sabarmati river basin dispute in Gujarat is one such example.

Rainwater Harvesting

It refers to the practice of conserving and using rainwater for later use. It is practised throughout the nation in places like Rajasthan, Western Himalayas, Northeast India, West Bengal and parts of South India. It is a viable alternative to major dam projects both socio-economically and environmentally.

In hilly and mountainous regions, communities build long water channels which bring water from glaciers to the villages. These channels are locally known as 'kuls' or 'guls'.

In Rajasthan, rooftop rainwater harvesting is a common practice. In parts of Rajasthan such as Bikaner, Phalodi and Barmer, almost every house has water storing tanks, locally known as tankas, in their houses. They also have community structure locally known as khadins and johads to save rainwater for agriculture.

In Bengal, people have developed inundation channels to irrigate their fields.

Tamil Nadu is the first state in India which has made rain-water harvesting structure compulsory in houses. There are legal provisions to punish the defaulters.