NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources

NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources Solutions to each chapter is provided in the list so that you can easily browse throughout different chapters NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources Notes and select need one. NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources Question Answers Download PDF. NIOS Study Material of Class 12 Environmental Science Paper Code 333.

NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources

Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Environmental Science Chapter 28 Ground Water Resources Solutions, NIOS Senior Secondary Course Environmental Science Solutions for All Chapter, You can practice these here.

Ground Water Resources

Chapter: 28

Module 8 A: Water Resource Management

Textual Question Answer

INTEXT QUESTIONS 28.1

1. What is groundwater?

Ans: Groundwater is the water that seeps below the Earth’s surface and is stored in the pores and spaces of soil and rocks. 

2. Where does it come from?

Ans: Part of rain water that infiltrates the earth’s surface slowly seeps downward into extensive layers of porous soil and rocks. 

3. What is an aquifer?

Ans: Under groundwater body is created called aquifer. 

4. What do you mean by water table?

Ans: Water table is the upper level of an underground surface in which the soil or rocks are permanently saturated with water. 

INTEXT QUESTIONS 28.3 

1. State two ways each for saving water.

(a) In bathrooms.

Ans: (i) Use a mug while shaving or brushing teeth. 

(ii) Turn off the water while soaping or shampooing. 

(b) At kitchen.

Ans: (i) Wash vegetables and dishes in a bowl instead of under running water.

(ii) Reuse leftover water from washing fruits/vegetables for plants.

2. Suggest two ways of judicious uses water while gardening and landscaping.

Ans: By building a rain garden or harvesting with rain water, one can save water while gardening and landscaping.

3. Give any two other judicious uses of water.

Ans: (i) to designate a water efficiency coordination. 

(ii) to develop a water efficiency plan.

INTEXT QUESTIONS 28.4 

1. What is artificial recharge?

Ans: Artificial recharge is a process by which excess surface water is directed into the ground – either by spreading on the surface by using recharge wells, or by altering natural conditions to increase infiltration. 

2. State two methods by which groundwater can be recharged artificially.

Ans: Through spreading basins, recharge pits and shafts, ditches and recharge wells. 

3. Give two advantages and disadvantages of artificial recharge?

Ans: Advantages:

(i) While recharging, rain and surface water infiltrate the soil and percolate down through the various geological formations and get naturally cleansed.

(ii) Very few special tools are needed to dig drainage wells.

Disadvantages:

(i) There is a potential for contamination of the groundwater from injected surface water runoff, especially from agricultural fields and road surfaces unless the surface water runoff is not pretreated before injection.

(ii) Unless significant volumes are injected into an aquifer, groundwater recharge may not be economically feasible.

INTEXT QUESTIONS 28.5 

1. How do mining activities affect groundwater?

Ans: Mine drainage discharge, solid mine tailings, process water, sludge lagoons, oilfield spillage of group gathering stations. 

2. Name any two contaminants of groundwater.

Ans: Urban and agricultural activities.

3. State two reasons for the decline of quality of groundwater.

Ans: Unsewered sanitation, sewage leakage, solid waste disposal, aerial fall out, landfill waste, poor housekeeping. 

INTEXT QUESTIONS 28.6 

1. State two reasons for reduction in water table.

Ans: Over-pumping of groundwater for irrigation/industries and less natural recharge due to reduced infiltration.

2. Give two reasons for lowering of water table.

Ans: Rapid increase in the rates of pumping of ground water has caused a steady lowering of water table levels. 

3. Mention two risks of reduced water table and contaminated groundwater.

Ans: The two risks of the reduced water table and contaminated groundwater are drying up of wells and reduction of water in streams.

TERMINAL EXERCISE

1. State three important differences between groundwater and surface water. 

Ans: The three important differences between groundwater and surface water are:

(i) Location: Groundwater is present below the Earth’s surface in soil pores and rock layers, whereas surface water is found on the Earth’s surface in rivers, lakes, ponds, and streams.

(ii) Accessibility: Groundwater usually requires drilling or pumping (from wells, borewells, or hand pumps) to use it, while surface water is directly available and visible.

(iii) Quality: Surface water may be fresh or saline (e.g., rivers vs. seas), while groundwater is generally fresh but can also be saline or contaminated in certain regions.

2. What is water table? 

Ans: Water table is the upper level of an underground surface in which the soil or rocks are permanently saturated with water.

3. How can you obtain groundwater? 

Ans: By means of drilling or pumping out, one can obtain the groundwater.

4. Describe in brief how water can be saved at home. 

Ans: Water can be saved at home in several ways such as by taking a shorter shower, turning off the running taps unnecessary, checking the toilet leaks, and using water when needed. Use of rainwater for harvesting.

5. What are the main groundwater quality problems in India? 

Ans: The main groundwater quality problems in India are:

(i) Declining groundwater table due to over-extraction for agriculture, industries, and domestic use, making wells and borewells dry.

(ii) Contamination with harmful chemicals such as pesticides, fertilizers, and industrial effluents.

(iii) Presence of toxic heavy metals like arsenic (in West Bengal, Bihar, Assam, etc.) and mercury in certain regions.

(iv) Excess fluoride and nitrates in groundwater in many states, leading to dental and skeletal fluorosis or health problems like “blue baby syndrome.”

(v) Salinity in groundwater in coastal and arid regions, reducing its usability for drinking and irrigation.

6. Explain the natural and anthropogenic contaminants of groundwater. 

Ans: The contaminants of groundwater are:

(i) Nitrates: The nitrates contaminate the groundwater. They come from industrial waste, sewage, fertilizers, and landfills. They dissolve with groundwater.

(ii) Pathogens: The discharge from sewage, livestock shelters, and landfills leads to the contamination of groundwater with pathogens.

(iii) Trace metals: Metals from thermal power plant waste contaminate groundwater and cause diseases.

(iv) Organic compounds: Pesticides pollute the groundwater when leached to the groundwater from the soil surface.

7. Describe the methods of artificially recharging groundwater.

Ans: Artificial recharge is the process of augmenting groundwater by allowing surface water to infiltrate the soil and percolate down to the aquifer. 

The main methods are:

Spreading methods:

Spreading basins: Water is spread over a large, flat permeable area to allow infiltration.

Flooding: Water is allowed to flood agricultural fields or open lands, which then seeps underground.

Recharge pits and shafts: Pits are shallow depressions, while shafts are deeper vertical structures filled with porous material (gravel, sand, pebbles) to allow rainwater or stormwater to percolate quickly.

Ditches and trenches: Long, narrow excavations that collect runoff water and allow it to percolate into the soil.

Recharge wells: Specially constructed wells that directly inject surface water or stormwater into deeper aquifers. They ensure faster recharge where thick impermeable layers exist.

Percolation tanks/ponds: Small tanks or ponds constructed to impound surface runoff and enhance groundwater recharge in nearby wells.

8. What are the main causes of groundwater depletion? 

Ans: Groundwater has been depleted due to an increase in its extraction for carrying out human activities. Agricultural use, domestic use, and industrial use are lowering the level of groundwater rapidly. Groundwater is accumulated slowly. Thus the age of the groundwater should be kept young by reducing the mining.

9. What are the main adverse effects of groundwater depletion? 

Ans: The crop-varieties that are responsible for the increased productivity of agriculture, all need water at a timely application. The lowering of groundwater tables is a threat to the sustainability of agriculture. The rivers as well as the wells are drying up due to excess extraction of groundwater. The cutting down of forests has disturbed the water cycle. The rainy seasons are causing floods and during the non-rainy period, drought is occurring. Groundwater is not unlimited. The recharging process is very slow, and the excessive extraction of groundwater is lowering the water tables. The groundwater gets contaminated by pathogens, pesticides, and trace metals.

10. How can quality of recharge water be maintained?

Ans: The use of water-efficient products, reducing wastage of water, and recycling of water should be done to save the water. The artificial recharge method helps in recharging the groundwater as well as in maintaining the quality of groundwater. The roots of plants do rhizofiltration. Thus the groundwater becomes suitable for drinking and does not need any filtration further. Thus planting more trees helps in maintaining the quality of recharged groundwater. The use of chemical fertilizers and pesticides in the agricultural fields should be minimized and organic farming should be promoted. The management of waste should be proper so that the groundwater could be free of contaminants. Recharging with less-saline water that is available on the surface so that the water could be used for agricultural fields and livestock.