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Irrigation and Drainage Engineering Flashcards

1
Q

The maximum permissible water velocity for clay loam canal surface based on PAES 603:2016 (AMTEC, 2016).
A. 1.2 m/s
B. 1 m/s
C. 0.9 m/s
D. 0.8 m/s

A

D. 0.8 m/s

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2
Q

The minimum permissible velocity for water with sediments in lined canals based on PAES 603:2016.
A. 1.2 m/s
B. 1 m/s
C. 0.9 m/s
D. 0.80 m/s

A

C. 0.9 m/s

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3
Q

Application of water in the soil to supply moisture needed for plant growth.
A. Flooding
B. Sprinkling
C. Irrigation
D. Diverting

A

C. Irrigation

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4
Q

Loss of water from a channel during transport due to seepage and percolation.
A. Channel loss
B. Seepage loss
C. Percolation loss
D. Conveyance loss

A

D. Conveyance loss

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5
Q

Depth of water flow where the energy content is at minimum hence, no other backwater forces are involved.
A. Minimum depth
B. Critical depth
C. Energy depth
D. Normal depth

A

B. Critical depth

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6
Q

Ratio of the actual crop evapotranspiration to its potential evapotranspiration.
A. Crop ratio
B. ET ratio
C. Crop coefficient
D. Evaporation ratio

A

C. Crop coefficient

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7
Q

Moisture content of the soil when gravitational water has been removed.
A. Soil capacity
B. Gravitational moisture
C. Field capacity
D. Specific capacity

A

C. Field capacity

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8
Q

Number of days between irrigation applications.
A. Irrigation interval
B. Application interval
C. Dry interval
D. Node interval

A

A. Irrigation interval

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9
Q

Removal of excess water.
A. Squeezing
B. Run off
C. Discharging
D. Drainage

A

D. Drainage

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10
Q

Elevated section of open channel used for crossing natural depressions.
A. Parshall flume
B. Flume
C. Siphon
D. Elevated channel

A

B. Flume

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11
Q

Surveying instrument used for determining land areas in a topographic maps.
A. Aerometer
B. Erometer
C. Planimeter
D. Lysimeter

A

C. Planimeter

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12
Q

Elevation of water surface in a stream with reference to a certain datum.
A. Stage
B. Surface elevation
C. Contour
D. Water elevation

A

A. Stage

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13
Q

Facility for determining water consumptive use of crops in an open field.
A. Planimeter
B. Lysimeter
C. Consumeter
D. Crop meter

A

B. Lysimeter

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14
Q

Time required to cover an area with one application of water.
A. Irrigation interval
B. Irrigation period
C. Supply duration
D. Application time

A

B. Irrigation period

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15
Q

At optimal emitter spacing, drip emitter spacing is _ of the wetted diameter estimated from field tests.
A. 100%
B. 90%
C. 80%
D. 85%

A

C. 80%

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16
Q

Reference crop evapotranspiration is the rate of evapotranspiration from a reference surface which is a hypothetical reference crop with an assumed crop height of 0.2 m and an albedo of ____ (AMTEC, 2020).
A. 0.23
B. 0.25
C. 0.30
D. 0.32

A

A. 0.23

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17
Q

Manufacturer’s coefficient of variation is the measure of the variability of discharge of a random sample of a given make, model and size of emitter, as provided by the manufacturer and before any field operations or aging has taken place determined through a discharge test of a sample of 50 emitters under a set pressure at oC.
A. 20
B. 100
C. 50
D. 30

A

A. 20 (PAES 608:2016 )

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18
Q

Which one is the flattest canal side slope?
A. 1:1
B. 1:4
C. 4:1
D. 2:1

A

C. 4:1

In specifying side slope, run is written first, ex. 4:1 means horizontal run is 4.
In computing angles whether bed slope or side slope, rise is the numerator.
Some fluid mechanics and hydraulics books use Ө symbol for side angle with the vertical plane, not with the horizontal. In this case subtract Ө from 90° to get angle with the horizontal plane.

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19
Q

Determine the side slope angle Ө with the horizontal plane of an unlined canal with side
slope ratio (run: rise) z of 2:1.
A. 16.6 degrees
B. 26.6 degrees
C. 45 degrees
D. 60 degrees

A

B. 26.6 degrees

tan θ = rise/run
θ = arctan(1/2)
θ = 26.6 degrees

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20
Q

If the most efficient concrete canal has its side angle Ө with the horizontal plane equal to 60 degrees, what is the z value of the canal sides or the side’s horizontal run in meters per 1 meter rise? This value is commonly used in designing most efficient concrete canals.
A. 0.775
B. 0.757
C. 0.577
D. 1/0.577

A

C. 0.577

tan θ = 1/z
tan 60 = 1/z
z = 0.577

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21
Q

What is the top width at water surface level of the most efficient concrete open channel if the design depth is 5 meters? The design discharge is 100 m3/s and velocity is 2 m/s.
A. 1.29 m
B. 9.12 m
C. 12.9 m
D. 19.2 m

A

C. 12.9 m (Check Tambong II for solution)

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22
Q

What is the total top width of the most efficient concrete open channel if design depth is 5 meters? Design discharge is 100 m3/s and velocity is 2 m/s. Use 15% freeboard.
A. 12.9 m
B. 13.8 m
C. 18.3 m
D. 8.13 m

A

B. 13.8 m (Check Tambong II for solution)

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23
Q

What is the base of the most efficient trapezoidal concrete open channel if discharge is 100m3/s and velocity is 2 m/s?
A. 6.14 m
B. 12.8 m
C. 7.21 m
D. 14.6 m

A

A. 6.14 m (Check Tambong II for solution)

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24
Q

What is the bottom width for the best hydraulic cross-section (best proportion) of concrete open channel if design depth is 5 meters and side slope is 45 degrees?
A. 3 m
B. 4 m
C. 5 m
D. 6 m

A

B. 4 m (Check Tambong II for solution)

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25
Q

What is the bottom width for best hydraulic cross-section of unlined open channel for
minimum seepage if design depth is 5 meters and side slope is 45 degree?
A. 3.15 m
B. 4.15 m
C. 8.15 m
D. 6.15 m

A

C. 8.15 m (Check Tambong II for solution)

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26
Q

What is the bottom width for best hydraulic cross-section of unlined open channel with minimum seepage if design depth is 5 meters and side slope is 2:1?
A. 4.72 m
B. 7. 42 m
C. 2.47 m
D. 7.24 m

A

A. 4.72 m (Check Tambong II for solution)

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27
Q

Estimate the width and depth of concrete-lined rectangular open channel for water velocity of 2 m/s and discharge of 10 m3/s.
A. 6.1 m, 2.3 m
B. 3.2 m, 1.6 m
C. 2.5m, 5.0 m
D. 13.6 m, 3.1 m

A

B. 3.2 m, 1.6 m (Check Tambong II for solution)

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28
Q

What should be the base and depth of concrete-lined rectangular open channel for a cross-sectional area of 50 m2? Design for efficiency over proportion.

A. 10 m, 5 m
B. 12 m, 6 m
C. 2.5 m, 5 m
D. 3 m, 6 m

A

A. 10 m, 5 m (Check Tambong II for solution)

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29
Q

What should be the depth and side angle with the horizontal of concrete-lined triangular open
channel for a cross-sectional area of 50 m2?

A. 5 m, 16.6o
B. 6 m, 26.6o
C. 7 m, 45o
D. 8 m, 60o

A

C. 7 m, 45o (Check Tambong II for solution)

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30
Q

What design depth of open channel would you recommend to carry 100 cumecs or cubic meters/sec with a velocity of 5 mps? Use the most efficient of all trapezoidal cross-sections.
A. 1.4 m
B. 2.4 m
C. 3.4 m
D. 1.3 m

A

C. 3.4 m (Check Tambong II for solution)

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31
Q

If the most efficient of all trapezoidal cross sections can be used, what actual depth of open channel would you recommend to carry 100 cumecs with a velocity of 5 mps? Use 15% freeboard.
A. 3.9 m
B. 3.5 m
C. 3.6 m
D. 1.3 m

A

A. 3.9 m (Check Tambong II for solution)

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32
Q

If an unlined trapezoidal canal with best hydraulic cross-section can be used, what actual depth of open channel would you recommend to carry 10 cumecs with a velocity of 1 mps? Use 2:1 side slope and 15% freeboard.
A. 1.12 m
B. 2.12 m
C. 21.2 m
D. 2.21 m

A

B. 2.12 m (Check Tambong II for solution)

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33
Q

The moisture content of the soil when the gravitational water has been removed.

a) Available water
b) Field capacity
c) Permanent wilting point
d) Readily available moisture

A

b) Field capacity

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34
Q

It is the ratio of the dry weight of soil particles to the weight of an equal volume of water.
a) Particle density
b) Bulk density
c) Real specific gravity
d) Apparent specific gravity

A

d) Apparent specific gravity

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35
Q

These are pipelines built on or near the ground surface to convey water across wide depressions?
a. Inverted siphons
b. Siphons
c. Laterals
d. Flumes

A

d. Flumes

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36
Q

Subsurface drain system wherein laterals join the submain on both sides alternately.
a. Gridiron
b. Herringbone
c. Parallel drain system
d. Double main system

A

b. Herringbone

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37
Q

Evapotranspiration in an 8 ha farm is 7mm/day and percolation losses is 2mm/day.
What is the design discharge of a canal to be
able to deliver a 5-day requirement of the
farm in 24 hours if irrigation efficiency is
75%?
a. 150 m3/hr
b. 200 m3/hr
c. 175 m3/hr
d. 140 m3/hr

A

b. 200 m3/hr
Q = Ad/t
Q = [(8 ha x 10,000 m2/ha) (7 mm/day + 2 mm/day) (1m/1000mm) (5 days)] / (24 hrs x 0.75)
Q = 200 m3/hr

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38
Q

If the impeller speed of a centrifugal pump is
increased from 1800 rpm to 2340 rpm, the
resulting power will be how many times the
original?
a. 1.690
b. 2.197
c. 1.091
d. 1.140

A

b. 2.197

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39
Q

Darcy’s law states that the flow of water through a porous medium is?
a. Proportional to the medium’s hydraulic conductivity
b. Inversely proportional to the length of flow path
c. Both a and b
d. Neither a nor b

A

c. Both a and b

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40
Q

One liter per second is equal to?
a. 16.85 gpm
b. 15.50 gpm
c. 15.85 gpm
d. 17.35 gpm

A

c. 15.85 gpm

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41
Q

It is the ratio of the volume of voids to the
total volume of the soil.
a. Void volume
b. Bulk density
c. Porosity
d. Void density

A

c. Porosity

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42
Q

A soil sample was obtained using a cylindrical soil sampler with a 4-inch diameter and 10-inch height. After oven-drying, the sample weighed 2,470 grams. What is the soil’s bulk density.
a. 12 g/cc
b. 1.1 g/cc
c. 1200 kg/m3
d. 1.3 kg/m3

A

c. 1200 kg/m3

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43
Q

It is the water retained about individual soil particles by molecular action and can be removed only by heating.
a. Permanent wilting point
b. Hygroscopic water
c. Hydrophobic water
d. Microscopic water

A

b. Hygroscopic water

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44
Q

Compute for the brake horsepower of a pump
needed to pump-out a fluid (ρ = 1.3 g/cc) at a
rate of 300 gpm with a total head of 6 meters.
Assume pump efficiency of 60%.
a. 2.5 hp
b. 3.0 hp
c. 3.5 hp
d. 5.0 h

A

c. 3.5 hp

BHP = QH/3960Eff x specific gravity

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45
Q

A 16-ft thick confined aquifer with hydraulic
conductivity of 500 ft/day was tapped by a 4-
inch diameter shallow tube well. With a
radius of influence of 2000 ft, determine the
maximum discharge of the STW in lps.
Assume an allowable drawdown of 10 ft.
a. 16.85
b. 17.55
c. 5.59
d. 6.59

A

b. 17.55 lps

Q = 2pikt(he-hw)/ln(re/rw) = ft3/day convert to lps

k- hydraulic conductivity
t - thickness
he-hw - drawdown
re - radius of influence
rw - radius of well

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46
Q

It refers to the composite parts of the
irrigation system that divert water from
natural bodies of water such as rivers,
streams and lakes.
a. Main canal
b. Diversion canal
c. Irrigation structures
d. Headworks

A

d. Headworks

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47
Q

It is a measure of the amount of water that
the soil will retain against a tension of 15
atmospheres.
a. Readily available moisture
b. Permanent wilting point
c. Available moisture
d. Field capacity

A

b. Permanent wilting point

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48
Q

Given a shallow tubewell with maximum
discharge of 15 lps and a total dynamic head
of 7 meters. Determine the power rating of
the primemover for the pump if pump and
primemover efficiencies are 60% and 55%,
respectively.
a. 4.0 hp
b. 3.5 hp
c. 4.5 hp
d. 5.0 hp

A

c. 4.5 hp

P (kW) = QH/102Eff

Q - lps
H - m

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49
Q

What is the discharge in each sprinkler nozzle
to irrigate a rectangular piece of land 150m x
180m if the laterals are set parallel to the
longer side of the field. Sprinkler spacing is
6m x 6m, irrigation water requirement is 150
mm and irrigation period is 6 hours.
a. 0.250 lps
b. 0.375 lps
c. 0.500 lps
d. 0.125 lps

A

a. 0.250 lps

Qs = (150 mm/hr)(1m/1000mm)(6mx6m)(1hr/3600s)(1000L/m3) = 0.25 lps

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50
Q

The International Soil Science Society
describes sand as a soil particle with a
diameter of
a. 0.02 to 2 mm
b. 0.2 to 2 mm
c. 0.002 to 0.02 mm
d. 0.002 to 0.2 mm

A

b. 0.2 to 2 mm

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51
Q

Ten m3/hr is equal to
a. 2.78 lps
b. 44.03 gpm
c. Both a and b
d. Neither a nor b

A

c. Both a and b

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52
Q

Determine the irrigation interval for a farm
with soil root zone having a field capacity of
200 mm and a wilting point of 105 mm.
Assume that the consumptive use for August
is 7.5 mm/day with no rainfall and the
allowable moisture depletion is 75%.
a. 11 days
b. 9 days
c. 4 days
d. 7 days

A

b. 9 days
Iint = (FC – WP)(AMD) / CU
= ((200 – 105)mm x 0.75) / 7.5 mm/day
Iint = 9.5 days or 9 days

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53
Q

What is the depth of water in a trapezoidal
channel with a side slope of 2 and carrying a
3.2 m3/s water flow? The channel’s bottom
width is 1.5 meters and the flowing water has
a velocity of 0.85 m/s.
a. 1.8 m
b. 1.79 m
c. 1.05 m
d. 1.04 m

A

c. 1.05 m
Q = AV
A = Q/V = 3.2 m3
/s / 0.85 m/s = 3.765 m2
A = by + zy^2
3.765 = 1.5y + 2y^2

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54
Q

The localized lowering of the static or
piezometric water level due to pumping.
a. Groundwater decline
b. Drawdown
c. Subsidence
d. Depression

A

b. Drawdown

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55
Q

Any convenient level surface coincident or
parallel with mean sea level to which
elevations of a particular area are referred
a. Datum
b. Elevation
c. Horizontal surface
d. Slope

A

a. Datum

56
Q

What is the design discharge of a canal to be
able to deliver a 7-day requirement of a 5-ha
farm in 12 hours if the irrigation requirement
is 8 mm/day?
a. 65 m3/s
b. 6.5 m3/s
c. 0.65 m3/s
d. 0.065 m3/s

A

d. 0.065 m3/s
Q = (5 ha x 10,000 m2/ha x 8 mm/day x (1m/1000mm) x 7 days) / 12 hrs x 1hr/3600sec
Q = 0.0648 m3/s = 0.065 m3/s

57
Q

It is a geologic formation which transmits
water at a rate in sufficient to be economically developed for pumping.
a. Aquifer
b. Aquiclude
c. Aquifuge
d. Aquitard

A

a. Aquifer

58
Q

Determine the maximum total head at which
a 5-hp centrifugal pump can extract water at
a rate of 25 lps if pump efficiency is 65%.
a. 25.32 ft
b. 32.48 ft
c. 33.39 ft
d. 35.12 ft

A

b. 32.48 ft

P (kW) = QH/102Eff

Q - lps
H - m

59
Q

It is the ratio of the dry weight of the soil to
the weight of the water with volume equal to
the soil bulk volume.
a. Particle density
b. Bulk density
c. Real specific gravity
d. Apparent specific gravity

A

d. Apparent specific gravity

60
Q

It accounts for the losses in an irrigation
system from the water source and prior to
delivery of water into the field ditches.
a. Evaporation
b. Application efficiency
c. Diversion efficiency
d. Conveyance efficiency

A

d. Conveyance efficiency

61
Q

A geologic formation that contains water but
do not have the capacity to transmit it.
a. Aquifuge
b. Aquifer
c. Aquitard
d. Aquiclude

A

d. Aquiclude

Aquifuge - An impermeable body of rock which contains no interconnected openings or interstices and therefore neither absorbs nor
transmits water.

Aquiclude - Any geological formation that absorbs and holds water but does not transmit it at a sufficient rate to supply springs, wells, etc.

An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well.

Aquitard - which is a bed of low permeability along an aquifer.

Aquiclude (or aquifuge), which is a solid, impermeable area underlying or overlying an aquifer.

62
Q

Compute the land soaking requirement for a
soil (depth of root zone = 60 cm) with residual
moisture content of 18% by weight, bulk
density of 1,320 kg/m3 and porosity of 50%.
Standing water for planting is 20 mm.
a. 177.44 mm
b. 157.44 mm
c. 253.44 mm
d. 273.44 mm

A

b. 157.44 mm

LSR = (n-(RMCxAs))(DRZ)

63
Q

What is the recommended value for standing
water during land preparation.
a. 5 mm
b. 10 mm
c. 15 mm
d. 8 mm

A

b. 10 mm

64
Q

Farm water requirement minus the application losses is the.
a. Diversion water requirement
b. Farm irrigation requirement
c. Application efficiency
d. Land preparation water requirement

A

b. Farm irrigation requirement

65
Q

What is the root zone depth of a farm with
land soaking requirement of 90 mm if the soil
porosity is 45%, residual moisture content is
18% (by weight) and bulk density is 1,250
kg/m3?
a. 35 cm
b. 40 cm
c. 45 cm
d. 60 cm

A

b. 40 cm

66
Q

This results from overlapping radii of influence of neighboring wells.
a. Drawdown
b. Groundwater decline
c. Well interference
d. Drawdown curve

A

c. Well interference

67
Q

In furrow irrigation, the rate of water application should be ____ the intake rate of the soil.
a. Less than
b. Greater than
c. Equal to
d. Not related to

A

a. Less than

68
Q

The localized lowering of the static or
piezometric water level due to pumping
a. Groundwater decline
b. Drawdown
c. Subsidence
d. Depression

A

b. Drawdown

69
Q

For a 10m x 10m sprinkler spacing, what is
the design sprinkler throw for a 50% overlap?
a. 15 m
b. 7.5 m
c. 8.0 m
d. 5.0 m

A

b. 7.5 m

10/2 +10/2*0.5 = 7.5 m

70
Q

Four liters per second is equivalent to
a. 14.4 m3/hr
b. 63.41 gpm
c. Both a and b
d. Neither a nor b

A

c. Both a and b

71
Q

Irrigation method is used for row crops
wherein only a part of the surface is wetted
a. Basin flooding
b. Furrow irrigation
c. Border irrigation
d. Border-strip flooding

A

b. Furrow irrigation

72
Q

The infiltration equation based on the exhaustion process is the
a. Lewis-Kostiakov’s
b. Horton’s
c. Philip’s
d. Darcy’s

A

b. Horton’s

73
Q

Determine the irrigation interval for a farm
with soil root zone having a field capacity of
200 mm and a wilting point of 140 mm.
Assume that the consumptive use is 6 mm/day
with no rainfall and the allowable moisture
depletion is 75%
a. 8 days
b. 9 days
c. 7 days
d. 10 days

A

c. 7 days
Int = (FC-WP)(AMD)/CU
= ((200-140)mm x 0.75)/6 mm/day
= 7.5 or 7 days

74
Q

What is the design discharge of a canal to be
able to deliver a 6-day requirement of a 6-ha
farm in 9 hours if the irrigation requirement is
8 mm/day?
a. 88.9 m3/s
b. 8.89 m3/s
c. 0.889 m3/s
d. 0.0889 m3/s

A

d. 0.0889 m3/s

75
Q

The amount of drainage water to be removed
per unit time per unit area is the
a. Drainage requirement
b. Drainage coefficient
c. Drain spacing
d. Drainage volume

A

b. Drainage coefficient

76
Q

In Hooghoudt’s drain spacing formula, it is assumed that
a. The water table is in equilibrium with
the rainfall or irrigation water
b. The drains are evenly spaced
c. Darcy’s law is valid for flow through soils
d. All of the above

A

d. All of the above

77
Q

A mathematical expression for the macroscopic flow of water through a porous system
a. Steady state groundwater flowequation
b. Darcy’s Law
c. Laplace’s equation
d. Scobey’s equation

A

b. Darcy’s Law

78
Q

It is the soil moisture constant describing the
amount of moisture retained by the soil
against a suction pressure of 1/3 atmosphere
a. Field capacity
b. Hygroscopic water
c. Permanent wilting point
d. Saturation point

A

a. Field capacity

79
Q

Run-off is the difference between the gross
depth of irrigation water and the
a. Net depth requirement
b. Crop evapotranspiration
c. Depth that infiltrated
d. Water use rate

A

a. Net depth requirement

80
Q

It is the type of sprinkler irrigation system
where the number of laterals installed is
equal to the total number of lateral positions
a. Hand move system
b. Periodic move
c. Special type
d. Set system

A

d. Set system

81
Q

In a drip system, the allowable pressure
variation in a lateral with minimum and
average head of 1.51 and 1.38 meters,
respectively is
a. 0.185 psi
b. 0.462 psi
c. 0.370 psi
d. 0.130 psi

A

b. 0.462 psi

1 m head = 1.422 psi

Allowable pressure variation (PAES 608:2016)

ΔHs = 2.5 (Ha - Hm)

ΔHs = 2.5(1.51 m - 1.38 m) = 0.325 m * 1.422 psi/m = 0.462 psi

82
Q

A soil with root zone depth of 1.2 meters has 24% initial volumetric moisture content, volumetric field capacity and permanent wilting point of 30% and 15%, respectively and 50% allowable moisture depletion. The initial depth of water in the soil is
a. 43.2 mm
b. 270 mm
c. 288 mm
d. 360 mm

A

c. 288 mm

Pv = d/D

d = Pv x D
d = 0.24 x 1.2 meters = 0.288 m

83
Q

It is a surface irrigation system where the area is subdivided by dikes and water flows over these dikes from one subdivision to another.
a. Border irrigation
b. Furrow irrigation
c. Basin irrigation
d. Corrugation irrigation

A

c. Basin irrigation

84
Q

Distribution control structures placed across an irrigation ditch to block the flow temporarily and to raise the upstream water level.
a. Turnouts
b. Checks
c. Culverts
d. Weirs

A

b. Checks

85
Q

Using Scobey’s equation for friction loss, a lateral with 10 sprinklers has a reduction coefficient of
a. 0.3766
b. 0.100
c. 0.200
d. 0.3964

A

d. 0.3964

(1/b+1) + (1/2N) + (sqrt(b-1)/6N^2)

where
b = 1.9 (exponent of Q in Scobey’s formula)
N = no. of sprinklers

86
Q

Which is not a component of the impact arm of an impact sprinkler?
a. Nozzle
b. Counterweight
c. Vane
d. Spoon

A

a. Nozzle

87
Q

A 20-ft thick confined aquifer with hydraulic conductivity of 400 ft/day was tapped by a 4-inch diameter shallow tube well. With a radius of influence of 2,500 ft, determine the maximum discharge of the STW in liters per second. Assume an allowable drawdown of 12 ft?
a. 22.17
b. 20.57
c. 62.71
d. 25.63

A

b. 20.57

88
Q

In surface irrigation, the ratio between the gross amount of irrigation water and the net requirement of the crop is the
a. Application efficiency
b. Deep percolation
c. Seepage
d. Runoff

A

a. Application efficiency

89
Q

It is an orderly sequence of planting crop in an area for a 365-day period
a. Cropping pattern
b. Crop combination
c. Crop sequence
d. Cropping schedule

A

a. Cropping pattern

90
Q

A 21.6 mm/day water requirement is equivalent to
a. 23.8 gpm/ha
b. 0.9 lps/ha
c. 2.5 lps/ha
d. 14.3 gpm/ha

A

c. 2.5 lps/ha

91
Q

In a 5 ha area, it was determined that the soil volumetric field capacity and permanent wilting point are 25% and 15%, respectively. Crop consumptive use is 5 mm/day, application efficiency is 80% and irrigation application rate is 32 m3/hr. The allowable soil moisture depletion is 60%, apparent specific gravity is 1.2 and the depth of root zone is 0.8 m. The net depth of irrigation water to be applied is
a. 80 mm
b. 48 mm
c. 24 mm
d. 36 mm

A

b. 48 mm

dnet = (AMD)(FC-PWP)(DRZ)
dnet = (0.6)(0.25-0.15)(800 mm) = 48 mm

92
Q

The head in an emitter discharging 4 liters of water per hour and with discharge coefficient of 0.798 and exponent of 0.5 is
a. 26.4 m
b. 25.0 m
c. 10 m
d. 21.8 m

A

b. 25.0 m (Check PAES 608:2016 - Table 4)

93
Q

In furrow irrigation, it is the difference between the depth of water that infiltrated and the net depth requirement
a. Runoff
b. Application losses
c. Deep percolation
d. Seepage

A

c. Deep percolation

94
Q

A rectangular piece of land 180m x 240m is laid out with one-sided sprinkler irrigation system. Laterals are set parallel to the longer side of the field. Sprinkler spacing is 6m x 6m, irrigation water requirement is 150 mm and irrigation period is 6 hours. Laterals are set on only one side of the mainline. The sprinkler discharge is
a. 0.50 lps
b. 0.375 lps
c. 0.250 lps
d. 0.125 lps

A

c. 0.250 lps

95
Q

In-line canal structure designed to convey canal water from a higher level to a lower level, duly dissipating the excess energy resulting from the drop in elevation
a. Drop
b. Flume
c. Weir
d. None of the above

A

a. Drop

96
Q

Amount of rainwater that falls directly on the field and is used by the crop for growth and development excluding deep percolation, surface runoff and interception
a. Average rainfall
b. Effective rainfall
c. Rainfall depth
d. None of the above

A

b. Effective rainfall

97
Q

Applicator used in drip, subsurface, or bubbler irrigation designed to dissipate pressure and to discharge a small uniform flow or trickle of water at a constant rate that does not vary significantly because of minor differences in pressure
a. Drippers
b. Emitters
c. Nozzle
d. None of the above

A

b. Emitters

98
Q

Closed conduit designed to convey canal water in full and under pressure running condition, to convey canal water by gravity under roadways, railways, drainage channels and local depressions
a. Siphon
b. Inverted siphon
c. Elevated flumes
d. None of the above

A

b. Inverted siphon (PAES 606:2016)

99
Q

Amount of water required in lowland rice production which includes water losses through evaporation, seepage and percolation and land soaking
a. Land soaking water requirements
b. Land preparation water requirements
c. Irrigation water requirements
d. None of the above

A

b. Land preparation water requirements

100
Q

Portion of the pipe network between the mainline and the laterals
a. Connector
b. Valve
c. Manifold
d. None of the above

A

c. Manifold

101
Q

Constant flow depth along a longitudinal section of a channel under a uniform flow condition
a. Normal depth
b. Critical depth
c. Uniform depth
d. None of the above

A

a. Normal depth

102
Q

Water flow that is conveyed in such a manner that top surface is exposed to the atmosphere such as flow in canals, ditches, drainage channels, culverts, and pipes under partially full flow conditions
a. Open channel flow
b. Canal flow
c. Pipe flow
d. None of the above

A

a. Open channel flow

103
Q

Tube or shaft vertically set into the ground at a depth that is usually less than 15 m for the purpose of bringing groundwater into the soil surface whose pumps are set above the water level
a. Shallow tubewell
b. Deep well
c. Pipe
d. None of the above

A

a. Shallow tubewell

104
Q

Ratio of the horizontal to vertical dimension of the channel wall
a. Slope
b. Channel gradient
c. Side slope
d. All of the above

A

c. Side slope

105
Q

Slope of the water surface profile plus the velocity head in open channels
a. Energy grade line slope
b. Water surface slope
c. Channel bottom slope
d. Hydraulic grade line slope

A

a. Energy grade line slope

106
Q

Slope of the free water surface in open channel
a. Energy grade line slope
b. Water surface slope
c. Channel bottom slope
d. Hydraulic grade line slope

A

d. Hydraulic grade line slope

107
Q

Occurs when flow has a constant water area, depth, discharge, and average velocity through a reach of channel
a. Normal flow
b. Critical flow
c. Uniform flow
d. Varied flow

A

c. Uniform flow

108
Q

Accounting of water inflows, such as irrigation and rainfall; and outflows, such as evaporation, seepage and percolation.
a. Water cycle
b. Water balance
c. Water flow
d. All of the above

A

b. Water balance

109
Q

Area which contributes runoff or drains water into the reservoir.
a. Watershed
b. River network
c. Streams
d. All of the above

A

a. Watershed

110
Q

Diameter of the circular area wetted by the sprinkler when operating at a given pressure and no wind.
a. Wetted diameter
b. Wetted perimeter
c. Diameter of throw
d. All of the above

A

a. Wetted diameter

111
Q

Portion of the perimeter of the canal that is in contact with the flowing water.
a. Wetted diameter
b. Wetted perimeter
c. Diameter of throw
d. All of the above

A

b. Wetted perimeter

112
Q

Moisture left in the soil before the initial irrigation water delivery which describes the extent of water depletion from the soil when the water supply has been cut-off.
a. Current soil moisture content
b. Residual moisture content
c. Allowable moisture depletion
d. None of the above

A

b. Residual moisture content

113
Q

Pressure required to overcome the elevation difference between the water source and the sprinkler nozzle, to counteract friction losses and to provide adequate pressure at the nozzle for good water distribution.
a. Average pressure
b. Design pressure
c. Pressure requirement
d. None of the above

A

b. Design pressure

114
Q

An overflow structure built perpendicular to an open channel axis to measure the rate of flow of water.
a. Weir
b. Flume
c. Orifice
d. None of the above

A

a. Weir

115
Q

In-line structure with a geometrically specified constriction built in an open channel such that the center line coincides with the center line of the channel in which the flow is to be measured.
a. Weir
b. Flume
c. Orifice
d. None of the above

A

c. Orifice

116
Q

Measuring device with a well-defined, sharp-edged opening in a wall through which flow occurs such that the upstream water level is always well above the top of this opening.
a. Weir
b. Flume
c. Orifice
d. None of the above

A

c. Orifice

117
Q

Determine the seepage and percolation losses within the canal if the difference in flow rates at 200-meter distance is 2 m3/s.
a. 1 liter/s-m
b. 0.1 m3/s-m
c. 0.01 m3/s-m
d. None of the above

A

c. 0.01 m3/s-m

(S&P)losses = (Qi - Qo)/L

Qi = inflow rate
Qo = outflow rate
L = length of channel reach

118
Q

A device with individual scales on the rods to provide data to plot furrow depth as a function of the lateral distance where data can then be numerically integrated to develop geometric relationships such as area verses depth, wetted perimeter versus depth and top-width verses depth.
a. Infiltrometer
b. Profilometer
c. Penetrometer
d. None of the above

A

b. Profilometer

119
Q

Application of water by gravity flow to the surface of the field.
a. Surface irrigation
b. Furrow irrigation
c. Basin irrigation
d. None of the above

A

a. Surface irrigation

120
Q

Method of irrigation where water runs through small parallel channels as it moves down the slope of the field.
a. Surface irrigation
b. Furrow irrigation
c. Basin irrigation
d. None of the above

A

b. Furrow irrigation

121
Q

Recommended slope for furrow irrigation method.
a. 0.05 % to 3.0 %
b. 2.0% to 5.0%
c. ≤ 0.1%
d. None of the above

A

a. 0.05 % to 3.0 %

a. 0.05 % to 3.0 % - Furrow
b. 2.0% to 5.0% - Border
c. ≤ 0.1% - Basin

122
Q

What should be the depth of water to be applied if the needed water depth is 6 mm and the application efficiency is 75%.
a. 4.5 mm
b. 6.0 mm
c. 8.0 mm
d. None of the above

A

c. 8.0 mm

dgross = dnet/Ea

dgross = 6 mm/0.75

123
Q

What should be the net depth of water to be applied if the depth of soil to be irrigated is 600 mm. The soil has a FC of 28%, PWP of 14% and the allowable moisture depletion is 50%.
a. 36 mm
b. 42 mm
c. 50 mm
d. None of the above

A

b. 42 mm

dnet = (FC - PWP)(DRZ)(MAD)

124
Q

What should be the irrigation frequency if the depth of water needed is 42 mm. The potential ET is 7.6 mm/day and the crop coefficient is 0.95.
a. 4 days
b. 6 days
c. 8 days
d. None of the above

A

b. 6 days

If = dnet/peakETa

ETa = 0.95 x 7.6 mm/day = 7.22 mm/day

If = 42 mm/7.22 mm/day = 5.82 days = 6 days

125
Q

What is the maximum sprinkler spacing, in square pattern, if the average wind speed is 5kph and below?
a. 55%
b. 50%
c. 45%
d. None of the above

A

a. 55% (PAES 608:2016 Part A - Table 1 & 2)

126
Q

What should be the sprinkler precipitation rate if the sprinkler spacing is 6m by 6m. The sprinkler discharge is 210 lph at 3 bars pressure with 14 meter wetted diameter.
a. 4.2 mm/hr
b. 5.8 mm/hr
c. 6.3 mm/hr
d. None of the above

A

b. 5.8 mm/hr (PAES 608:2016 10.1.3 Sprinkler Selection)

q = SlSmr

q = 0.00111Cdn^2P^1/2

(210 lph x 1 m3/1000L) = (6m x 6m)r

r = 5.83 mm/hr

127
Q

A trapezoidal channel has a base width of 6 meters and a side slope of 1H:1V. The channel bottom slope is 0.0002 and the Manning roughness coefficient is 0.014. What is the depth of flow if Q = 12.1 m3/s?
a. 1.5 m
b. 1.3 m
c. 1.7 m
d. 1.1 m

A

a. 1.5 m

A = bd + zd^2
P = b + 2dsqrt(1 + z^2)
Q = (A/n)(R)^2/3S^1/2 (Manning’s Equation)

128
Q

A trapezoidal channel has a base width of 6 meters and a side slope of 1H:1V. The channel bottom slope is 0.0002 and the Manning roughness coefficient is 0.014. What will be the state of flow if the depth of flow is 1.5 m?
a. Critical
b. Sub-critical
c. Supercritical
d. Laminar

A

b. Sub-critical

F = V/sqrt(gD)

129
Q

What is the required power if the needed system capacity is 25 m3/hr and the total dynamic head is 40 meters. The pump efficiency is 60%.
a. 3 hp
b. 5 hp
c. 7 hp
d. None of the above

A

c. 7 hp

P = QH/102Eff = 6.2 hp, choose 7 hp.

130
Q

Determine the nominal pipe diameter for the 20 m3/hr flow if the allowable velocity in pipe is 2 m/s.
a. 50 mm
b. 63 mm
c. 75 mm
d. None of the above

A

b. 63 mm

131
Q

Any barrier constructed to store water.
a. Reservoir
b. Dam
c. Tank
d. None of the above

A

b. Dam

132
Q

Volume of water stored in reservoir between the minimum water level and normal water level.
a. Active storage
b. Dead storage
c. Storage capacity
d. None of the above

A

a. Active storage

133
Q

Maximum elevation the water surface which can be attained by the dam or reservoir without flow in the spillway.
a. Maximum storage elevation
b. Dam crest elevation
c. Normal storage elevation
d. None of the above

A

c. Normal storage elevation

134
Q

Part of water impounding system that stores the runoff.
a. Watershed
b. Reservoir
c. Dam
d. None of the above

A

c. Dam

135
Q

What is the critical depth for a grassy triangular channel with 2H:1V side slopes and a 0.5% slope when the flow is 3.00 m3/s?
a. 1.23 m
b. 1.36 m
c. 0.86 m
d. 0.78 m

A

c. 0.86 m

A^3/T = Q^2/g

A = flow area
T = top width
Q = channel flow rate
g = gravitational acceleration

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