Question 1

Question 5What is tank irrigation?

Accepted Answer

Tank irrigation refers to irrigation in which water stored in artificially constructed tanks is used for irrigation. Tanks are constructed in areas of natural depression by building earthen embankments or masonry walls to collect water.

Question 2

Question 6What are the advantages and disadvantages of tank irrigation?

Accepted Answer

Advantages of tank irrigation are:Tank irrigation is cheaper and is prevalent in Deccan plateau where natural pits and depressions are found.As the water is collected and used in dry season, it uses the water table of the surrounding region.It is difficult to build canals in the Deccan plateau regions.The tank water is used for domestic purposes in villages.In the absence of perennial rivers and canals, tanks provide a source of water during the dry season.Disadvantages of tank irrigation are:Since tanks are shallow, large amount of water is wasted through evaporation.Tanks are non-perennial and dry up in summer. Considering this and the large area they occupy, they become costly in comparison to wells and tube wells.Tanks use up large areas of land which could be used for agriculture.

Question 3

Question 12For an Indian farmer state two advantages that well irrigation has over canal irrigation.

Accepted Answer

Two advantages that well irrigation has over canal irrigation for an Indian farmer are:Well is simplest and cheapest source of irrigation and the poor Indian farmer can easily afford it.Well is an independent source of irrigation and can be used as and when the necessity arises. Canal irrigation, on the other hand, is controlled by other agencies and cannot be used at will.

Question 4

Question 13What is the difference between surface water resource and groundwater resource? State two advantages of each.

Accepted Answer

S. No.Surface water resourceGroundwater resource1.Surface water is available on the surface of earth in the form of rivers, lakes, ponds and canals.Groundwater is the part of rainwater that seeps into the ground through the cracks and crevices.2.Surface water resources are mostly seasonal.Ground water is available throughout the year and is recharged every monsoon.3.Can be used directlyRequires pumping4.Usually contaminatedUsually fit for drinkingAdvantages of Surface water resource:The surface water is easily available for drinking and irrigation.The surface water is used for thermoelectric power.Advantages of Groundwater resource:The ground water is reliable source of water for drinking.It is not wasted by evaporation.

Question 5

Question 18Give two reasons why tube well irrigation is more important in northern India than in southern India.

Accepted Answer

Tube well irrigation is more important in northern India than in southern India because:The land in southern India is rocky while the land in norther India is softer, which makes it easy and cheap to dig tube wells.The southern India has other water sources like sea, tanks, ordinary wells etc.

Question 6

Question 24How is rainwater harvesting done? Explain.

Accepted Answer

Rainwater harvesting is done byStoring rainwater and later using it in dry season - Harvesting of rainwater is done by storing it in tanks, ponds and Dams. The stored water is used directly for irrigation and other domestic purposes.Recharging of groundwater - It is done by Rooftop rainwater Harvesting Method. Rainwater can be collected over the rooftops and can be channelized through small PVC pipes into the underground pits, sump, wells or borewells.

Question 7

Question 27Give geographical reasons —River Damodar is called "river of sorrow".Irrigation by canals is more suitable in northern India as compared to the south.Tank irrigation is used in peninsular India.

Accepted Answer

River Damodar was earlier called "river of sorrow" because of its ravaging floods in the plains of West Bengal which caused heavy losses and destruction. With the construction of several dams the floods of Damodar river have been greatly reduced but even now the floods sometimes affect the lower Damodar Valley.Canal irrigation is more suitable in northern India as compared to the south because the northern rivers are perennial and can supply water to canals throughout the year but the rivers of south India are seasonal and therefore, canals are of no use in dry season.The peninsular India has natural depressions which act as natural tanks and the rocky surface does not allow percolation of water. Therefore, tank irrigation is used in peninsular India.

Question 8

Question 29State the advantages and disadvantages of Sprinkler Irrigation.

Accepted Answer

Advantages of Sprinkler Irrigation are:This type of irrigation does not involve any wastage of water by seepage or evaporation as water is supplied through pipes and not exposed to the sun.This is the best method for conservation of water.It is best suited for arid and semi-arid regions.Water management is easier than surface irrigation system.Higher application efficiency.Frequent application is possible.Does not interfere with the cultivation.Easy mechanization and automation.Chemical and fertilizer application can easily be used with sprinkler system.Disadvantages of Sprinkler Irrigation:High initial cost.High operating cost.Water application efficiency under sprinkler irrigation is strongly affected by direction of the wind.Some crops are sensitive and may suffer leaf scorch because of salt deposited on the leaves after the water evaporates.High maintenance requirements as constant and meticulous maintenance of sprinkler system is very important.Saline water may cause problems.Water must be free from sand debris and salt.

Question 9

Question 30Name the modern methods of Irrigation.

Accepted Answer

The modern methods of Irrigation areSprinkler IrrigationDrip IrrigationBamboo Irrigation

Question 10

Question 31Study the picture and answer the questions that follows :Name the type of irrigation.What are the advantages of this type of irrigation?

Accepted Answer

Drip IrrigationAdvantages of Drip Irrigation are:Fertilizer and nutrient loss is minimized due to localized and reduced leaching.Water application efficiency is high if managed correctly.Field levelling is not necessary.Recycled or non-potable water can easily be used.Moisture within the root zone can be maintained at field capacity.Soil erosion is less.Water distribution is highly uniform.Labour cost is less.Variation in supply can be regulated by regulating the valves and drippers.Fertilization can be included with minimum waste of fertilizers.Usually operated at low pressure thereby reducing energy costs.

Question 11

Question 1(d)Rajasthan faces water scarcity, particularly in dry areas. The government has initiated water harvesting projects to enhance water availability.(i) What is meant by water harvesting?(ii) State the objectives of water harvesting schemes.

Accepted Answer

(i) Rainwater harvesting is the process of increasing the recharge of groundwater by capturing and storing rainwater locally in sub-surface water reservoirs.(ii) The main objectives of rainwater harvesting are the following:Meeting the ever increasing demand for water.Reducing the run-off which chokes drains.Avoiding the flooding of roads.Augmenting the groundwater storage and raise the water table.Reducing groundwater pollution.Improving the quality of groundwater.Reducing the soil erosion.Supplementing domestic water requirement during summer and drought.

Question 12

Question 2(c)Give a geographical reason for each of the following:(i) Inundation canals are being converted to perennial canals.(ii) Tank irrigation is preferred over other means of irrigation in Peninsular India.(iii) Groundwater reserves are depleting at a fast rate.

Accepted Answer

(i) Inundation canals are being converted to perennial canals because inundation canals get supply of water only when the rivers are in flood while perennial canals can draw water throughout the year and irrigate large areas.(ii) Tank irrigation is preferred over other means of irrigation in Peninsular India because-The rivers of Deccan are mainly dependent on the rainwater.Many streams become torrential during the rainy season but dry up when the rain ceases.The hard rocks in the area do not absorb waters, wells cannot be made there.The terrain is uneven with many natural depressions where tanks can be easily built.(iii) Groundwater reserves are depleting at a fast rate due to increase in population, irrigation and industrialisation, the demand for water has risen. This has led to a decline in groundwater level in various parts of the country.

Question 13

Question 2(d)(i) What is meant by traditional or conventional methods of irrigation?(ii) Name any two conventional methods of irrigation.

Accepted Answer

(i) Traditional methods of irrigation means to supply water to the plant zone by pumped water from surface or subsurface sources like ponds, rivers, channels or groundwater through earthen channels or pipes with gravitational force.(ii) Two conventional methods of irrigation are wells and tanks.

Question 14

Question 3(a)State any two drawbacks of conventional methods of irrigation.

Accepted Answer

Two drawbacks of conventional methods of irrigation are-A large quantity of water is not properly utilised.The fields situated in low areas always get excess water causing prolonged water logging.

Question 15

Question 3(b)Give two advantages and two disadvantages of well irrigation.

Accepted Answer

Two advantages of well irrigation are-Wells can be dug at a very low cost which is well within the means of poor farmers.By the use of pumps and tubewells, water can be lifted even from great depths.Two disadvantages of well irrigation are-Wells depend on underground water resources whose distribution varies from region to region.The traditional wells dry up due to over withdrawal of the ground water and lowering of the water table.

Question 16

Question 3(c)Give a geographical reason for each of the following:(i) Well irrigation is confined mainly to the alluvial plains.(ii) In Tamil Nadu, nearly one-third of the net irrigated area is under canal irrigation.(iii) Drip irrigation reduces loss of water through evaporation.

Accepted Answer

(i) Well irrigation is confined mainly to the alluvial plains as owing to the soft nature of the soil, wells can be easily dug and the yield of crops from the land after irrigation is considerably high.(ii) In Tamil Nadu, nearly one-third of the net irrigated area is under canal irrigation because Tamil Nadu receives rainfall during the winter season while summer season remains dry. Thus, irrigation is needed in summer to make up the lack of rainfall.(iii) Drip irrigation reduces loss of water through evaporation as this system consists of perforated pipes that are placed between rows of crops or buried along their root lines and give water directly on to the crops.

Question 17

Question 4(b)How are the fields irrigated using the Persian wheel method?

Accepted Answer

Persian wheel method is a partly submerged vertical wheel with buckets attached to the rim. As the wheel is turned by draught animals rotating a geared horizontal wheel, the buckets are filled and emptied into a trough above, which carries the water to crop-sown fields.

Question 18

Question 4(c)Give a geographical reason for each of the following:(i) Canals make the soil infertile.(ii) Tubewell irrigation is quite expensive.(iii) Excessive accumulation of salts make the soils unsuitable for cultivation.

Accepted Answer

(i) Canals make the soil infertile because in canal irrigation, where water table is a few feet below the ground, the alkaline salts come to the surface, mix with the soil and make it unproductive.(ii) Tubewell irrigation is quite expensive as it requires continuous supply of electricity.(iii) Excessive accumulation of salts make the soils unsuitable for cultivation because when salt concentrations in the soil are high, the movement of water from the soil to the root is slowed down. When the salt concentrations in the soil are higher than inside the root cells, the soil will draw water from the root, and the plant will wilt and die. Hence, the soil becomes unsuitable for cultivation.

Question 19

Question 4(d)Canals are a channel for supply of water from rivers to the farm fields. The perennial canals are not only an advantage but can be disadvantageous too. The perennial canals are functional in the state of Punjab due to the favourable situations available there.(i) What conditions favour the development of canal irrigation in the mentioned area?(ii) State two disadvantages of it.

Accepted Answer

(i) The following conditions favour the development of canal irrigation in Punjab:Presence of rivers (like Sutlej, Beas, and Ravi)Gentle slope of landExtensive farmlandsLow rainfallAlluvial soil(ii) Two disadvantages of Canal irrigation (perennial) are as follows:In areas where perennial unlined canals flow at ground level and between raised high banks, the water table may rise excessively, leading to waterlogging and swamp formation, rendering the soil uncultivable.Waterlogging reduces the soil's ability to absorb water, so even slight excess rainfall can flood the land, damaging crops, homes, and stored goods due to poor drainage.

Question 20

Question 5(a)Briefly explain why groundwater levels are dropping rapidly in India.

Accepted Answer

The groundwater levels are dropping rapidly in India due to the following reasons:The over-exploitation of groundwater is mainly responsible for the lowering of water table.Excessive extraction for agriculture, especially through borewells, has led to a significant decline in the water table.This issue is further worsened by a reduction in rainfall, which limits the natural recharge of groundwater.Industrial use and the growing demand from a rising population also contribute to this rapid depletion.

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