Test 21 - Crops, Water Requirements and Irrigation Efficiency

Question 1 ప్రశ్న 1

In irrigation engineering, what is meant by the crop water requirement under standard, well-watered conditions?

A The total canal-head diversion including all conveyance losses B The quantity of water required to compensate the crop evapotranspiration during its growing period C Only the rainfall received during the crop season D The amount of water stored below permanent wilting point

Question 2 ప్రశ్న 2

Why can two crops grown at the same location have different seasonal water requirements?

A Because crop duration, canopy development, rooting characteristics and crop coefficients can differ B Because reference evapotranspiration must have a different unit for each crop C Because rainfall can fall on only one crop in the same field D Because hydraulic conductivity of irrigation water changes with crop species

Question 3 ప్రశ్న 3

Which crop-season pairing is most representative of Indian irrigation planning, while allowing for regional exceptions?

A Rice predominantly kharif and wheat predominantly rabi B Wheat predominantly kharif and rice only rabi C Sugarcane only a one-month summer crop and wheat a monsoon crop D All major crops belong exclusively to the same season throughout India

Question 4 ప్రశ్న 4

A crop is grown during a hot summer period between the principal rabi and kharif seasons in a region having little effective rainfall. What irrigation implication is most reasonable?

A Its irrigation requirement may form a large fraction of its crop water requirement because effective rainfall is small and climatic demand may be high B Its irrigation requirement must be zero because summer crops cannot evapotranspire C All summer crop water must come from rainfall D The crop coefficient automatically becomes zero

Question 5 ప్రశ్న 5

Under otherwise comparable climatic conditions, which statement about representative irrigation crops is generally reasonable?

A A long-duration crop such as sugarcane can have a much larger seasonal water requirement than a short-duration pulse crop B Every crop necessarily requires exactly the same seasonal irrigation depth C Short-duration pulses must always consume more water than sugarcane D Crop duration has no possible effect on seasonal water requirement

Question 6 ప్రశ్న 6

For many field crops, why does water requirement vary during different crop growth stages?

A Because canopy cover, leaf area and crop coefficient change as the crop develops B Because one hectare changes its physical area during the season C Because reference evapotranspiration must be zero at mid-season D Because soil porosity becomes equal to crop coefficient at maturity

Question 7 ప్రశ్న 7

For a 30-day growth stage, reference evapotranspiration is 5.0 mm/day and the crop coefficient is 1.10. What is the crop water requirement represented by ETc for this stage?

A 110 mm B 150 mm C 165 mm D 330 mm

Question 8 ప్రశ్న 8

Why can the irrigation-water requirement of a conventionally flooded paddy field exceed the crop evapotranspiration alone?

A Because irrigation planning may also have to account for requirements such as land preparation, puddling and percolation or seepage losses B Because rice does not transpire C Because effective rainfall must always be added twice D Because crop evapotranspiration has units of discharge rather than depth

Question 9 ప్రశ్న 9

Which expression best represents net irrigation requirement when crop evapotranspiration is ETc, effective rainfall is Pe and a specified usable contribution from stored soil water is Ws, with other contributions neglected?

A NIR = ETc - Pe - Ws B NIR = ETc + Pe + Ws C NIR = Pe - ETc D NIR = ETc × Pe × Ws

Question 10 ప్రశ్న 10

A crop has seasonal ETc = 520 mm. Effective rainfall supplies 140 mm and usable initial soil-water storage supplies 30 mm. Neglecting other contributions, what is the net irrigation requirement?

A 320 mm B 350 mm C 380 mm D 690 mm

Question 11 ప్రశ్న 11

A field has a net irrigation requirement of 350 mm and a field application efficiency of 70%. What field irrigation depth must be delivered to the field to satisfy the net requirement?

A 245 mm B 350 mm C 500 mm D 700 mm

Question 12 ప్రశ్న 12

The net irrigation requirement is 350 mm, field application efficiency is 70% and conveyance efficiency from canal head to field head is 80%. What gross irrigation depth is required at the canal head?

A 437.5 mm B 500 mm C 560 mm D 625 mm

Question 13 ప్రశ్న 13

An irrigation system has conveyance efficiency of 85% and field application efficiency of 75%. Neglecting other loss components, what is its overall irrigation efficiency?

A 60.0% B 63.75% C 80.0% D 160.0%

Question 14 ప్రశ్న 14

An irrigation system releases 100 units of water at the canal head. Of this, 80 units reach the field head and 56 units are beneficially stored for crop use in the root zone. What are the conveyance efficiency, application efficiency and overall efficiency respectively?

A 80%, 70%, 56% B 70%, 80%, 56% C 80%, 56%, 70% D 56%, 70%, 80%

Question 15 ప్రశ్న 15

Immediately before irrigation, a crop root zone requires 90 mm of water to reach the desired storage condition. The irrigation event actually stores 72 mm in the root zone. What is the water-storage efficiency?

A 20% B 72% C 80% D 125%

Question 16 ప్రశ్న 16

A crop has a net seasonal irrigation requirement of 400 mm over an area of 600 hectares. What net irrigation-water volume is required?

A 0.24 × 10^6 m³ B 1.20 × 10^6 m³ C 2.40 × 10^6 m³ D 24.0 × 10^6 m³

Question 17 ప్రశ్న 17

A command area of 1000 hectares requires a gross seasonal irrigation depth of 500 mm at the relevant supply point. What seasonal volume does this represent?

A 0.5 × 10^6 m³ B 2.0 × 10^6 m³ C 5.0 × 10^6 m³ D 50 × 10^6 m³

Question 18 ప్రశ్న 18

An irrigation scheme must deliver 4.32 × 10^6 m³ of water uniformly over a 50-day supply period. What continuous average discharge is required?

A 0.50 m³/s B 1.00 m³/s C 2.00 m³/s D 5.00 m³/s

Question 19 ప్రశ్న 19

A scheme irrigates 300 ha of Crop A having a net seasonal requirement of 400 mm and 200 ha of Crop B having a net requirement of 250 mm. What is the combined net irrigation-water volume?

A 1.20 × 10^6 m³ B 1.50 × 10^6 m³ C 1.70 × 10^6 m³ D 3.40 × 10^6 m³

Question 20 ప్రశ్న 20

The combined net irrigation requirement of a command is 1.70 × 10^6 m³. If overall irrigation efficiency from the project supply point to useful root-zone storage is 68%, what gross volume must be supplied?

A 1.16 × 10^6 m³ B 1.70 × 10^6 m³ C 2.50 × 10^6 m³ D 3.40 × 10^6 m³

Question 21 ప్రశ్న 21

A crop has a seasonal crop water requirement of 600 mm. In Year X, effective rainfall is 250 mm, while in Year Y it is only 100 mm. With all other useful water contributions equal to zero, how do the net irrigation requirements compare?

A Year X requires 350 mm and Year Y requires 500 mm B Year X requires 600 mm and Year Y requires 600 mm C Year X requires 850 mm and Year Y requires 700 mm D Year X requires 250 mm and Year Y requires 100 mm

Question 22 ప్రశ్న 22

For a fixed net irrigation requirement of 300 mm, field application efficiency improves from 60% to 75%. By what percentage does the required gross field-applied depth decrease?

A 15% B 20% C 25% D 40%

Question 23 ప్రశ్న 23

In a water-scarce irrigation command, which cropping-pattern decision would generally reduce seasonal irrigation demand, provided agronomic, economic and food-production objectives also remain acceptable?

A Increasing the area under the most water-intensive long-duration crops regardless of local conditions B Replacing part of a highly water-demanding crop area with suitable lower-water-requirement crops C Ignoring effective rainfall while estimating crop demand D Reducing irrigation efficiency deliberately

Question 24 ప్రశ్న 24

A crop has three simplified growth stages: 20 days with ETo = 4 mm/day and Kc = 0.50; 30 days with ETo = 5 mm/day and Kc = 0.80; and 40 days with ETo = 6 mm/day and Kc = 1.00. What is the total crop evapotranspiration over these 90 days?

A 300 mm B 360 mm C 400 mm D 440 mm

Question 25 ప్రశ్న 25

A crop requires 500 mm of ETc, receives 100 mm of effective rainfall and has no other useful water contribution. If the overall irrigation efficiency is 64%, what gross irrigation depth is required at the project supply point?

A 400 mm B 500 mm C 625 mm D 781.25 mm

Question 26 ప్రశ్న 26

Consider the following statements about crop water requirement and irrigation efficiency: I. Crop water requirement varies with crop type, growth stage and climate. II. Effective rainfall reduces the amount that must be supplied by irrigation. III. Field application efficiency compares useful irrigation water with water delivered for field application. IV. If conveyance efficiency is Ec and application efficiency is Ea, their product gives the corresponding combined efficiency when no additional efficiency components are introduced. Which option is correct?

A I and II only B I, II and III only C II, III and IV only D I, II, III and IV

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