Water Resources

What is water scarcity? What are the causes of water scarcity?

The shortage of water as compared to its demand is known as water scarcity.

1. Due to low rainfall and seasonal and annual variation of rainfall patterns especially in dry regions with very little rainfall like Rajasthan.

2. The overuse of irrigation especially for food grains during dry spells.

3. Increased usage of water for domestic needs,

4. Intestive industrialsation and urbanisation

5. Many housing colonies and farms have access to their own groundwater pumps leading to depletion of groundwater reserves.

6. Water Pollution

Why do we need to conserve water?

1. To safeguard people from the health hazards caused by drinking toxic water

2. To ensure food security

3. To ensure continuation of livelihood and productive activities.

4. To prevent degradation of natural ecosystems.

Give examples of hydraulic structures in ancient India.

1. 1st Century BC , Sringaverapura near Allahabad had water harvesting systems for channeling the flood waters of river ganga.

2. During the rule of Chandragupta Maurya , many dams , lakes and irrigation systems were built.

3. Evidences of irrigation systems in ancient India also have been found in Kalinga and Nagarjunakoda.

4. Bhopal lake was the largest artificial lake in the 11th century.

5. 14th Century , tank in Hauz Khan was constructed by Iltutmish for supplying water to Siri Fort.

Write a short note on dams , its uses and its types.

1. A damn is a barrier across flowing water that obstructs ,directs or slows down the flow of water often creating a reservoir or a lake.

2. Most dams have a section called a spillway or weird through which the river water flows continuosly.

3. Based on material and structure dams are classified as timber dams , embankment dams and masonry dams.

4. Based on height they can be classified as large dams and major dams or low dams , medium height dams and high dams

5. It is used for the following

   1. Regulate rivers and collect rainwater which was used to irrigate agricultural fields.

   2. They supply water for domestic and industrial use

   3. They help in the generation of hydroelectricity.

   4. Flood control

   5. Inland navigation

   6. Recreation and Tourism

   7. Fish breeding

6. Multipurpose river projects were launched after independence in India as the were believed to lead the nation to development and progress.

7. Jawaharlal Nehru proclaimed multi purpose river projects as the Temples of Modern India because they combine development of agriculture and village economy with rapid industrialisation and urbanisation.

What are the negative impacts of multi-purpose water projects?

1. The reservoirs create flood plains leading to the degradation of soils and increase in the salination of soil.

2. Improved irrigation due to dams lead to farmers switchin more to cash crops that are water intensive , leading to salination of soil and lack of production of other crops.

3. Excessive sedimentation at the bottom of the reservoicers.

4. It can lead to water borne diseases and pests

5. The local people are displaced for the construction of multi purpose water projects.

6. Damns increase the conflict between the social groups over the same water resource

7. Help mostly the rich and increase the gap between the rich and the poor

8. Causes inter state water disputes.

9. Harms the aquatic life

What are guls or kuls

In hilly mountain areas , gulls or kuls are diversion channels that are built to divert the water flowing from the mountains.

What are Khadins and Johads

1. The agriculture fields are converted into rainwater storage structures

2. It allows the water to seep into the soil.

3. It increases the moisture content of the soil

4. Replenishes the groundwater

What are Innundation Chennels

In the flood plains of Bengal , people develop innundation channels , which is a channel that is connected to a large river so that the flood water in the reviers flows through it to irriagate their fields

What is the bamboo drip irrigation system?

1. The system in practice for over 200 years in Meghalaya.

2. It uses water from streams and springs in the hills get transported to agricultural fields by using bamboo as pipes.

3. The water then slowly drips into the roots of each plant through these bamboo pipes.

How is Rooftop Rainwater Harvesting in Rajasthan?

1. It is mainly practised to store drinking water , It was mainly used to store drinking water. It is practised in Rajasthan , Gendathur village in Mysuru , Karnataka and towns and villages of Thar.

2. Tankas - are underground tanks built for storing water inside the main house or the courtyard.

3. These tanks are connected to the sloping roofs and travel down a pipe in the underground tanks.

4. The rainwater which is called as palar pani can be used when other sources are dried up.

5. The first spell of rain is not collected as this would clean the roofs and pipes.

6. Many houses contrsucted underground rooms adjoining the tanka to avoid the summer heat as it would keep the room cool.

How is Rooftop Rainwater Harvesting practised in Shillong and Karnataka?

1. Rooftop rainwater harvesting is most common practice in Shillong , Meghalaya , Cherapunjee and Mawsynram recieve the highest rainfall in the world.

2. Despite high rainfall they face water shortages and every household in the city has a rooftop rainwater harvesting structure.

3. Gendathur is a backward village in Mysuru , Karnatak which receives an annual precipitation of 1000mm.

4. Every house in the village has a rooftop rainwater harvesting and can collect and use about 50,000 litres of water annualy.

What are the advantages of rainwater harvesting?

1. It is considered as the purest form of natural water and a good source of drinking water.

2. This water can be used for agricultural purposes.

3. The water stored under the ground in tanks helps in cooling basement rooms in the hot summer.