## Water Requirement of Crops Important Question For GATE

Water Requirement of Crops Important Question For GATE Aspiring to conquer in Civil Engineering? The key lies in mastering the critical domain of water requirement for crops. This blog post dives deep into essential questions, offering insights that will irrigate your knowledge base and help your GATE aspirations bloom.

## One mark question

**Q 1)** A sprinkler irrigation system is suitable when ?

(a) the land gradient is steep and the soil is easily erodible.

(b) the soil is having low permeability

(c) the water table is low

(d) the crops to be grown have deep roots

**[GATE-2004]**

**Q 2)** The intensity of irrigation for the Kharif season is 50% for an irrigation project with culturable/ command area of 50,000 hectares. The duty for the Kharif season is 1000 hectare/cumec. Assuming transmission loss of 10%, the required discharge (in cumec, up to two decimal places) at the head of the canal is____?

**[GATE-2018, SHIFT-I]**

**Q 3)** The two columns below show some parameters and their possible values:

Parameters | Value |
---|---|

P - Gross Command Area | II - 100 hectares/cumec |

Q - Permanent Wilting Point | II - 6 °C |

R - Duty of canal water | III - 1000 hectares |

S - Delta of wheat | IV - 1000 cm |

V - 40.0cm | |

VI - 0.12 |

Which of the following options matches the parameters and the values correctly?

(a) P-I, Q-II, R-III, S-IV

(b) P-III, Q-VI, R-I, S-V

(c) P-I, Q-V, R-VI, S-Il

(d) P-III, Q-II, R-V, S-IV

**[GATE-2015 SET-I]**

**Q 4)** The consumptive use of water for a crop during a particular stage of growth is 2.0 mm/day.

The maximum depth of available water in the root zone is 60 mm. Irrigation is required when the amount of available water is 50% of the maximum available water in the root zone. Frequency of irrigation should be

(a) 10 days

(b) 15 days

(C) 20 days

(d) 25 days

**[GATE-2007]**

**Q 5)** In a cultivated area, the soil has porosity of 45% and field capacity of 38%. For a particular crop, the root zone depth is 1.0 m, the permanent wilting point is 10% and the consumptive use is 15 mm/day. If the irrigation efficiency is 60%, what should be the frequency of irrigation such that the moisture content does not fall below 50% of the maximum available moisture?

(a) 5 days

(b) 6 days

(c) 9 days

(d) 11 days

**[GATE-2006]**

**Q 6)** The moisture content of soil in the root zone of an agricultural crop at certain stage is found to be 0.05. The field capacity of the soil is 0.15. The root zone depth is 1.1 m. The consumptive use of crop at this stage is 2.5 mm/day and there is no precipitation during this period. Irrigation efficiency is 65%. It is intended to raise the moisture content to the field capacity in 8 days through irrigation. The necessary depth of irrigation is

(a) 115 mm

(b) 169 mm

(c) 200 mm

(d) 285 mm

**[GATE-2003]**

**Q 7)** The total irrigation depth of water required by a certain crop in its entire growing period (150 days), is 25.92 cm. The culturable command area for a distributary channel is 100,000 hectare. The distributary channel shall be designed for a discharge

(a) less than 2 cumecs

(b) 2 cumecs

(c) 20 cumecs

(d) more than 20 cumecs

**[GATE-2003] **

**Q 8)** If duty (D) is 1428 hectares/cumec and base period (B) is 120 days for an irrigated crop, then delta (Δ) in metres is given by

(a) 102.8

(b) 0.73

(C) 1.38

(d) 0.01

**[GATE-2000]**

**Q 9)** Delta (Δ) in cm, Duty (D) in hectare/cumec and Base period (B) in days are related as

(a) Δ= 864B/D

(b) B= 864D/Δ

(c) B = 864Δ/D

(d) D = 8.64B/Δ

**[GATE-1996]**

## two marks questions

**Q 10)** The culturable command area of a canal is 10,000 ha. The area grows only two crops-rice in the Kharif season and wheat in the Rabi season. The design discharge of the canal is based on the rice requirements, which has an irrigated area of 2500 ha, base period of 150 days and delta of 130 cm. The maximum permissible irrigated area (in ha) for wheat, with a base period of 120 days and delta of 50 cm. is___?

**[GATE-2017 SET-II]**

**Q 11)** A field channel has Cultivable Command Area of 2000 hec. The intensity of irrigation for gram and wheat are 30% and 50% respectively. Gram has kor period of 18d, kor depth 12 cm, while wheat has 18 days and 15 cm. The discharge (m^{3}) required in the field channel to supply water to the command area during kor period is____?

**[GATE-2015 SET-II]**

**Q 12)** Irrigation water is to be provided to a crop in field to bring the moisture content of the soil from the existing 18% to the field capacity of the soil at 28%. The effective root zone of the crop is 70 cm. If the densities of the soil and water are 1.3 g/cm" and 1g/cm respectively. depth of irrigation water (in mm)-

**[GATE-2014 SET-II]**

**Q 13)** The transplantation of rice requires 10 days and total depth of water required during transplantation is 48 cm. During transplantation, there is an effective rainfall (useful for irrigation) of 8 cm. The duty of irigation water (in hectares/cumec) is:

(a) 612

(b) 216

(c) 300

(d) 108

**[GATE-2013]**

**Q 14)** Wheat crop requires 55 cm of water during 120 days of base period. The total rainfall during this period is 100 mm. Assume the irrigation efficiency to be 60%. The area (in ha) of the land which can be irrigated with a canal flow of 0.01 m^{3}/s is

(a) 13.82

(b) 18.85

(c) 23.04

(d) 230.40

**[GATE-2012]**

**Common Data for Questions 15 and 16.**

The moisture holding capacity of the soil in a 100 hectare farm is 18 cm/m. The field is to be irrigated when 50% of the available moisture in the root zone is depleted. The irrigation water is to be supplied by a pump working for 10 hours a day, and water application efficiency is 75%. Details of crops planned for cultivation are as follows :

Crop | Root Zone Depth (m) | Peak rate of moisture use (mm/day) |

X | 1.0 | 5.0 |

Y | 0.8 | 4.0 |

**Q 15)** The area of crop Y that can be irrigated when the available capacity of irrigation system is 40 l/s

(a) 40 hectare

(b) 36 hectare

(c) 30 hectare

(d) 27 hectare

**[GATE-2010]**

**Q 16)** The capacity of irrigation system required to irrigate crop X in 36 hectares is

(a) 83 l/S

(b) 67 l/s

(c) 57 ls

(d) 53l/s

**[GATE-2010]**

**Q 17)** An agricultural land of 437 hectare is to be irrigated for as particular crop. The base period of the crop is 90 days and the total depth of water required by the crop is 105 cm. If a rainfall of 15 cm occurs during the base period, the duty of irrigation water is

(a) 437 hectare/cumec

(b) 486 hectare/cumec

(c) 741 hectare/cumec

(d) 864 hectare/cumec

**[GATE-2009]**

**Q 18)** An outlet irrigates an area of 20 ha. Discharge (Us) required at this outlet to meet the evapotranspiration requirement of 20 mm occurring uniformly in 20 days neglecting other field losses

(a) 2.52

(b) 2.31

(c) 2.01

(d) 1.52

**[GATE-2008]**

**Q 19)** The Culturable Command Area for a distributed channel is 20,000 hectares. Wheat is grown in the entire area and the intensity of irrigation is 50%. The kor period for wheat is 30 days and the kor water depth is 120 mm. The outlet discharge for the distributary should be

(a) 2.85 m^{3}/s

(b) 3.21 m^{3}/s

(c) 4.63 m^{3}/s

(d) 5.23 m^{3}/s

**[GATE-2007]**

**Q 20)** The culturable commanded area for a distributary is 2 × 108 m^{2}. The intensity of irrigation for a crop is 40%. If kor water depth and kor period for the crop are 14 cm and 4 weeks, respectively, the peak demand discharge is

(a) 2.63 m^{3}/s

(c) 8.58 m^{3}/s

(b) 4.63 m^{3}/s

(d) 11.58 m^{3}/s

**[GATE-2005]**

**Q 21)** A canal irrigates a portion of a culturable command area to grow sugarcane and wheat. The average discharges required to grow sugarcane and wheat are, respectively, 0.36 and 0.27 cumec. The time factor is 0.9. The required design capacity of the canal is

(a) 0.36 cumec

(b) 0.40 cumec

(c) 0.63 cumec

(d) 0.70 cumec

**[GATE-2004]**

**Q 22)** A canal was designed to supply the irrigation needs of 1200 hectares of land growing rice of 140 days base period having a Delta of 134 cm. If this canal water is used to irrigate wheat of base period 120 days having a Delta of 52cm, the area (in Hectares) that can be irrigated is

(а) 2650

(b) 3608

(c) 543

(d) None of the above solution

**[GATE- 2002]**

**Q 23)** A field was supplied water from an irrigation tank at a rate of 120 lit/sec to irrigate an area of 2.5 hectares. The duration of irrigation is 8 hours. It was found that the actual delivery at the field, which is about 4 km from the tank, was 100 lit/sec. The runoff loss in the field was estimated as 800 m3. The application efficiency in this situation is

(а) 62%

(b) 72%

(C) 76%

(d) 80%

**[GATE-2001]**

**Q 24)** A tube well having a capacity of 4m^{3}/hour operates for 20 hours each day during the irrigation season. How much area can be commanded if the irrigation interval is 20 days and depth of irrigation is 7 cm?

(a) 1.71 × 10^{4}m^{2}

(b) 1.14 × 10^{4}m^{2}

(c) 22.9 × 10^{4}m^{2}

(d) 2.29 × 10^{4}m^{2}

**[GATE-2000]**

## Five Marks Questions

**Q 25)** A reservoir is proposed to be constructed to command an area of 1,20,000 hectares. The area has monsoon rainfall of about 100 cm per year. It is anticipated that sugar and rice would each be equal to 20% of the command area and wheat equal to 50% of the command area, making a total of annual irrigation equal to 90% of the command area.

- (I) Work out the storage required for the reservoir, assuming the water requirements given below, canal losses as 25% of the head discharge and reservoir evaporation and dead storage losses as 20% of the gross capacity of the reservoir.
- (II) Determine also the full supply discharge of the the canal at the head of the canal.

Crop | Sowing Time | Harvesting Time | Total WaterDepth (in cm) | "Kor" Period in Weeks | "Kor" Watering (in cm) |

Transplanted Rice | July | November | 150 | 2.5 | 19.0 |

Sugar Cane | Feb - Mar | Dec - Mar Next year | 90 | 4 | 16.5 |

Wheat | October | March - April | 37.5 | 4 | 13.5 |

Note that Δ = 864B / D in which Δ = Depth of water in cm,

B = base period in days,

and D = duty of water in hectares/cumec.

**[GATE-1998]**

**Q 26)** In a farmland irrigated by a system of pumps from wells, the area irrigated is 50 hectares. Water pumped from wells is conveyed through a canal to the farms. Efficiency of water conveyance is 85% and pumps work at 12 hours/day. Available moisture holding capacity of the soil is 20cm per metre depth and the average root zone depth is 1m. Water application efficiency is 80%. Irrigation is started when moisture extraction level of 50% of available moisture is reached. Peak rate of moisture use by plants is 5mm. Calculate the irrigation period in days and total pumping capacity required in litres/minute.

**[GATE-1997]**

**Q 27)** A river valley consists of 14 hectare of irrigable land to be used for growing a crop whose peak consumptive use is 5 mm/day. If the average daily precipitation on the valley is 20 mm/day of which 2.0 mm is available for the crop and the irrigation system is operated for 12 hrs a day, determine the discharge in the irrigation stream if field irrigation efficiency is 50%.

**[GATE-1996]**

**Q 28)** The gross commanded area for an irrigation canal is 15,000 hectares out of which 80 percent is cultural commanded area. The intensity of irrigation is 50 percent for rabi. If the kor period is 4 weeks for rabi, determine the

- (i) outlet discharge. The outlet factor for rabi may be assumed as 1800 hectares/cumec.
- (ii) also calculate the delta for rabi.

**[GATE-1994]**

**Q 29)** The base period, duty at field and areas to be irrigated for various crops under a reservoir are as given below:

No. | Crop | Base Period (days) | Duty at field (ha/cumec) | Area of Crop (hectare) |

1 | Wheat | 120 | 1,700 | 2,800 |

2 | Rice | 110 | 1,000 | 3,200 |

3 | Sugar cane | 360 | 900 | 5,000 |

4 | Vegetables | 130 | 750 | 1,500 |

Find the reservoir capacity in hectare metres if the canal losses are 18% and reservoir losses are 10%.

**[GATE-1992]**

**Q 30)** The consumptive use requirements of a crop are 0.2 cm per day for days 1 to 15; 0.3 cm per day for days 16 to 40; 0.5 cm/day for days 41 to 50 : and 0.1 cm/day for days 51 to 55.

Effective rainfall of 3.5 cm, distributed uniformly during the 36th to 45th days (both inclusive), is predicted. Compute the total quantity of water (in m3) to be delivered to a 50 hectare plot for the whole crop season with a pre-sowing requirement of 5 cm of water.

**[GATE-1991]**

To understand all the fundamental regarding IRRIGATION ENGINEERING & HYDRAULIC STRUCTURES do visit the following category

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