Water Resources

Question 1

What are water resources?

Answer 1

The term water resources refers to any of the entire range of natural waters that occur on earth and are of potential use to living beings.

Question 2

What is surface water?

Answer 2

Water on land as a result of precipitation or seepage from underground which forms streams, lakes, rivers and ponds flowing on land which finally joins the sea.

Question 3

What is ground water?

Answer 3

• Water which seeps through the cracks and crevices under the surface of the land is known as ground water.
• It remains in the soil, subsoil or bedrock.

Question 4

Define an aquifer

Answer 4

An underground stream that is saturated with water and transmits water readily is known as an aquifer.

Question 5

Expand CGWB

Answer 5

Central Ground Water Board

Question 6

Why do we need to conserve water?

Answer 6

• Overexploitation of groundwater leads to reduction in water table.
• Loss of vegetation causes drought and leads to reduction of rainfall & water-table.
• Increase in population results in water scarcity
• Water resources are polluted and can hardly be used w/o adequate treatment

Question 7

What is rainwater harvesting?

Answer 7

• Rainwater harvesting is the process of increasing recharge of groundwater by capturing and storing rainwater locally in sub surface water reservoirs.

Question 8

What activities does rainwater harvesting include?

Answer 8

1. Harvesting surface and ground water
2. Prevention of losses of water through evaporation and seepage.
3. All other hydrological studies and engineering for water conservation.

Question 9

What are objectives of rainwater harvesting?

Answer 9

1. Meeting the ever increasing demand for water
2. Reducing run-off which chokes the drains.
3. Avoiding flooding of roads.
4. Augmenting the groundwater storage and raise the water table.
5. Reducing groundwater pollution.
6. Improving quality of groundwater
7. Reducing soil erosion.

Question 10

Name the various storing mechanisms in different parts of the country.

Answer 10

1. Khatri/Kuhl - Western Himalayas
2. Baolis/Dighis - Gangetic Plains
3. Johads - Central India
4. Bhandaras/Kere - Deccan Plateau
5. Surangam - Western Ghats
6. Korambu - Eastern Ghats
7. Zing - Ladakh

Question 11

What is a watershed?

Answer 11

Watershed is an area that draining to a common point. This makes it an ideal unit for conservation of both soil and water.

Question 12

What is watershed management?

Answer 12

• Watershed management refers to the efficient management of both the surface and the groundwater resources.
• It includes prevention of run-off as well as storage and recharge of groundwater by various methods like percolation pits, recharge wells, bore wells, dug wells, etc.

Question 13

Why do we have acute shortage of water in India?

Answer 13

• Not cared to conserve water
• Rainfall in India occurs in short spells of high intensity.
• Most of the rain falling on the surface tends to flow away rapidly.

Question 14

What are elements of water harvesting?

Answer 14

1. Catchements
2. Conduits
3. Storage Facility
4. Recharge Facility

Question 15

What is catchement?

Answer 15

The catchment of a water harvesting is a surface which receives rainfall directly.

Examples
- courtyard of a building
- paved area like terrace
- unpaved area like open grounds

Question 16

What are conduits?

Answer 16

Conduits are the pipelines or drains that carry rain water from the catchment or rooftop to the harvesting system

Question 17

Examples of materials that conduits are made of:

Answer 17

• polyvinyl chloride PVC
• asbestos
• galvanized iron
• commonly available materials

Question 18

What are storage facilities for rainwater?

Answer 18

Rainwater can be stored in any commonly used storage containers like RCC, masonry or plastic water tanks

Question 19

Give examples of recharge facilities for rainwater

Answer 19

• borewells
• dug wells
• recharge pits
• percolation pits (soakaways)
• recharge trenches
• permeable surfaces
• porous tiles

Question 20

What are Borwells and dugwells?

Answer 20

• used to raise the underground water table
• Rainwater is collected on rooftop of building which is then diverted by drain pipes to filtration tank.
• From there it close into a bore well or dug well.

Question 21

what are recharge pits?

Answer 21

Recharge pits are excavated into the ground line with break or stone walls with opening at regular intervals

Question 22

What are percolation pits or soakaways?

Answer 22

Percolation pits are bored holes of 30 cm diameter drill in the ground up to a depth of 3 to 10 m

Question 23

What are recharge trenches?

Answer 23

Recharge trenches are excavated on ground and refilled with porous media like pebbles boulders break to harvest surface runoff

Question 24

How are permeable surfaces used to recharge groundwater?

Answer 24

Permeable surfaces like patches of grass are used to retain a large proportion of the rainwater falling on it only 10 to 15% as run off.

Question 25

How can we store water for direct use?

Answer 25

- By help of underground RCC installed in basement or outside the building - By help of Pre fabricated tank such as PVC - Tanks must have overflow system which may be connected to the drainage

Question 26

Generally run of from only pave surfaces is used for storing give reason.

Answer 26

Since it is relatively free of bacteriological contamination

Question 27

Define rooftop rainwater harvesting

Answer 27

Rooftop rainwater harvesting is the process of water harvesting in which rain water falling on a roof is diverted through drain pipes to the storage containers.

Question 28

GR: Water quality improves over time during storage in the tank.

Answer 28

because impurities settle down in the tank if the water is not disturbed and even pathogenic organisms gradually die out due to storage.

Question 29

Define irrigation

Answer 29

Irrigation refers to the process of watering of agricultural plants through artificial means such as wells, tanks, tubewells, etc.

Question 30

What is the need of irrigation in India?

Answer 30

**1. Uncertainty of Rainfall:** Rainfall in India is highly irregular in place and time, and rainfall in India occurs in short spells of high intensity. **2. Uneven Distribution of Rainfall** - Rainfall distribution in India is quiet uneven - Rainfall occurs from june to sept brought by SW Monsoon winds. - Some places get very heavy rainfall while some places get very less rainfall. **3. Crop Requirements:** - grain crops require more water during the time earheads are formed. - zaid crops (summer crops) are exclusively irrigated as monsoon does not occur at the time they're grown unlike kharif and rabi crops. - High Yielding Varieties require higher quantity of chemical fertilizers therefore need to be well-irrigated. - Commercial crops like sugarcane require higher quantity of water. **4. Nature of soil.** - Amt. of Irrigation req Depends on nature of soil. Ex: clayey soils have high moisture retention, less irrigation, Sandy soil has less moisture retention capabilities hence drip irrigation is suited there. **5. Utilizing water effectively** - Many non-perennial rivers of central and southern India only have water during the monsoons

Question 31

State two advantages of Well irrigation.

Answer 31

Wells are dug at a low cost. • Oxens which are kept for ploughing the land can be utilized for drawing water from the wells at no extra cost.

Question 32

What are the conditions required for drilling a tube well

Answer 32

• Level land and soft soil • Large fertile area in the surrounding • Availability of regular and cheap electricity to run the tube wells.

Question 33

State two advantages of tube well irrigation.

Answer 33

• Independent source of water • Brings up clean water • It can irrigate a large area.

Question 34

What are the disadvantages of tube wells?

Answer 34

• Excessive use of water leads to depletion of ground water. • Expensive as it requires continuous supply of electricity. • It is useless if the water is brackish.

Question 35

State two conditions necessary for tank irrigation.

Answer 35

• Presence of natural depressions • Hard rock strata.

Question 36

State the disadvantages of tank irrigation.

Answer 36

• Tanks occupy a large area which could be used for growing crops. • When monsoons fail tanks go dry. • Tanks are shallow so water gets evaporated.

Question 37

What are the drawbacks of conventional methods of irrigation?

Answer 37

• Large quantity of water is not properly utilized. • Some area of land is utilized in preparing channels which decreases effective area of cultivation.

Question 38

What is drip irrigation?

Answer 38

Ans. It is the system consisting of perforated pipes that are placed between the rows of crops or buried along the root and gives water directly to the crops.

Question 39

Give three reasons to justify the need to conserve water.

Answer 39

• Overexploitation of underground water results in the lowering of the water table. • The increase in population results in water scarcity. • Loss of vegetation causes drought and reduction in rainfall.

Question 40

What is Rainwater harvesting?

Answer 40

Ans.Rainwater harvesting is collecting and storing rainwater for a later use

Question 41

What is Watershed management

Answer 41

Ans.It refers to the efficient management and conservation of both surface and groundwater resources.

Question 42

Why are perennial canals preferred over inundation canals?

Answer 42

Ans. Perennials canals have water throughout the year and two or more crops can be grown.

Question 43

Why is canal irrigation more popular in Northern India?

Answer 43

• The rivers are perennial • Presence of flat land • Soft soil for easy digging.