ABE TUTORIALS

VOLUME 8- AREA 2

1. Difference in moisture content of soil between field capacity and permanent wilting point.

a. available moisture

b. reality available moisture

c. irrigation water requirement

d. saturation capacity

Explanation: Available moisture (AM) is the range of water held in the soil that can be extracted by plants, defined mathematically as Field Capacity (FC) minus Permanent Wilting Point (PWP).

2. The sum total of water lost in a given area thru transpiration from plants, evaporation from soil and water surface and for building tissues of plants.

a. Consumptive use

b. Deep percolation

c. runoff

d. seepage

Explanation: Consumptive Use (CU), often used interchangeably with Evapotranspiration (ET), accounts for all water used by the plant for growth and metabolic processes plus evaporation.

3. Water held by forces of surface tension and continuous film around soil particles is termed as:

a. hygroscopic water

b. gravitational water

c. capillary water

d. sea water

Explanation: Capillary water is the primary source of water for plants, held in the soil micro-pores against the force of gravity by surface tension.

4. Small Water Impounding Management (SWIM) Projects, In general, are those small scale water-impounding dams which have structural heights of not more than:

a. 45 m

b. 50 m

c. 30 m

d. 100 m

Explanation: Under Philippine guidelines, SWIM projects typically refer to dams with a structural height not exceeding 30 meters.

5. It is the soil moisture allowable depletion of most crops.

a. 50%

b. 20%

c. 80%

d. 100%

Explanation: Management Allowed Depletion (MAD) is commonly set at 50% for most crops to prevent water stress while maximizing irrigation intervals.

6. If the suction lift is 6 meters, the suited type of pump is:

a. Axial Flow

b. Centrifugal

c. Submersible

d. mixed flow

Explanation: Centrifugal pumps are effective for suction lifts up to 6–8 meters (approx. 20–25 ft) at sea level.

7. The moisture content of the soil when the tension is 15 atmospheres.

a. wilting pint

b. wilting coefficient

c. Field capacity

d. saturation point

Explanation: The Permanent Wilting Point (or wilting coefficient) occurs when soil moisture is held at a tension of approximately 15 bars or atmospheres.

8. What is term for capillary water in the smaller pore space of the soil?

a. Interception

b. depression storage

c. basin recharge

d. soil moisture

Explanation: Soil moisture refers to the water stored in the soil profile, predominantly as capillary water within the pore spaces.

9. What is the term for water that penetrates into the soil and flows laterally in the surface soil to a stream channel?

a. run-off

b. interflow

c. percolation

d. all of the above

Explanation: Interflow (or subsurface stormflow) is the portion of water that infiltrates the soil but moves laterally through the upper soil layers to reach a stream.

10. What is the term referring to the rate of surface run off and the rate of rainfall to reach an equilibrium?

a. Run off coefficient

b. infiltration rate

c. overflow

d. time of concentration

Explanation: Time of concentration is the time required for a drop of water to travel from the most remote point of the watershed to the outlet; at this point, the entire watershed is contributing to the runoff.

11. What is the line defined by the water level in a group of artesian wells?

a. water table

b. piezometric surface

c. specific yield

d. none of the above

Explanation: In a confined (artesian) aquifer, the piezometric surface represents the imaginary level to which water would rise if the confinement were removed.

12. What is the term for capillary water in the smaller pore surfaces of the soil? (Duplicate of #8)

a. Interception

b. depression storage

c. basin recharge

d. soil moisture

Explanation: This represents the moisture available for plant roots within the soil matrix.

13. What is the term for water that penetrates into the soil and flows laterally in the surface soil to the stream channel? 

a. run-off

b. interflow

c. percolation

d. all of the above

Explanation: Lateral movement within the soil profile toward a channel is defined as interflow.

14. What is the term required to the rate of surface run off and the rate of rainfall to reach an equilibrium? 

a. Run off coefficient

b. infiltration rate

c. overflow

d. time of concentration

Explanation: It is the duration after which the discharge becomes constant given a constant rainfall intensity.

15. What is the line defined by the water level in a group of artesian wells? (Duplicate of #11)

a. water table

b. piezometric surface

c. specific yield

d. none of the above

Explanation: Also known as the potentiometric surface.

16. What is the maximum quantity of water that can be guaranteed during a critical period?

a. specific yield

b. reservoir yield

c. safe yield

d. secondary yield

Explanation: Safe yield refers to the sustainable amount of water that can be withdrawn from a source (like a well or reservoir) without causing undesired effects.

17. Which is the best method of irrigation for irregular topography?

a. flooding

b. furrow

c. sprinkling

d. sub-irrigation

Explanation: Sprinkler irrigation is ideal for uneven land because it does not require land leveling, unlike surface methods.

18. Which is the best method of irrigation for row crops?

a. flooding

b. furrow

c. sprinkling

d. sub-irrigation

Explanation: Furrow irrigation is specifically designed for crops planted in rows, as water flows through the channels between the plant beds.

19. Which method of irrigation has the best control of water supplied?

a. flooding

b. furrow

c. sprinkling

d. sub-irrigation

Explanation: Sprinkler and drip systems provide highly accurate control over the volume and rate of water application compared to surface flooding.

20. The locus of the elevation to which water will rise in a piezometric tube?

a. hydraulic gradient

b. energy gradient

c. friction gradient

d. velocity gradient

Explanation: The Hydraulic Grade Line (HGL) represents the sum of the elevation head and the pressure head.

21. The hydraulic radius of a pipe with a diameter of 12 mm:

a. 3 mm

b. 12 mm

c. 6 mm

d. 4 mm

Explanation: For a pipe flowing full, Hydraulic Radius (R) = Diameter (D) / 4. Calculation: 12 mm / 4 = 3 mm.

22. Groundwater as a source of water for plant growth, thru capillary action, is effective only if the ground water is?

a. Above the rootzone

b. Within the depth from which the major needs of the plants are extracted

c. Way below the rootzone

d. All of the above

Explanation: For capillary rise to be useful, the water table must be close enough to the root zone for water to be pulled up into the effective rooting depth.

23. The best way of managing a farm with high water table to obtain optimum yield.

a. Frequent application of high irrigation thru sprinkler during the growth season

b. Application of heavy sprinkler irrigation during the rainy season

c. Application of large amount of irrigation water by surface method during the growing season

d. Non-application of water during the entire period of growing season

Explanation: If a high water table provides enough water through capillary rise to meet the crop's consumptive use, additional irrigation is unnecessary and may cause waterlogging.

24. The sum total of head above the vapor pressure of the liquid being pumped at a given pumping temperature.

a. required net positive suction head

b. total dynamic head

c. pump static head

d. total static head

Explanation: Net Positive Suction Head (NPSH) is critical to prevent pump cavitation.

25. The recommended variation in the lateral between the first and the last sprinkler.

a. 20%

b. 50%

c. 70%

d. 100%

Explanation: Standard design for sprinkler laterals limits the pressure (and thus discharge) variation to 20% to ensure uniform water application.

26. The rate at which water percolates through the soil surface.

a. Irrigation

b. Drainage coefficent

c. soil permeability

d. infiltration rate

Explanation: Infiltration rate is the velocity at which water enters the soil from the surface.

27. The most simple form of open-channel flow computation is:

a. unsteady uniform flow

b. steady uniform flow

c. steady non-uniform flow

d. unsteady non-uniform flow

Explanation: Steady uniform flow (where depth and velocity do not change with time or distance) is the basis for the Manning Equation.

28. The part of the dam that release surplus of flush flood water which cannot be contained in the active storage of the reservoir.

a. free board

b. spill way

c. gates

d. weir

Explanation: A spillway is a safety structure designed to bypass floodwater to prevent the dam from overtopping.

29. The most efficient trapezoidal cross-section:

a. width of the bottom = twice the depth

b. depth = twice the bottom

c. width of the bottom = 4x the depth

d. width of the top = 2x sum of sides

Explanation: For a "best hydraulic section" of a trapezoidal channel (half-hexagon), the bottom width is approximately equal to 1.15 times the depth, but in simple rectangular/trapezoidal theory, "bottom width = 2 * depth" is often taught as the efficient baseline.

30. A piece of land divided into strips by small earth bunds, usually sloping uniformly away from the farm channel in the direction of water flow.

a. basin

b. border

c. contour

d. furrow

Explanation: Border irrigation involves dividing the field into rectangular strips separated by parallel ridges (bunds).

31. Free flow in artesian well occur when:

a. the piezometric level is higher than the top of the well

b. The unconfined aquifer is beneath a confined aquifer

c. permeability is high

d. none of the above

Explanation: A flowing artesian well occurs when the natural pressure in the confined aquifer is sufficient to push the water above the ground surface.

32. In the identification of potential dam sites, which one is not part of the guidelines?

a. high density population to supply the needed labor

b. availability of potential service areas

c. availability of a narrow gorge

d. topographic condition providing a wide upstream reservoir

Explanation: While labor is needed, "high density population" is actually a disadvantage because it increases the cost and difficulty of relocating residents and property submerged by the reservoir.

33. The artificial application of water to the soil for the purpose of crop production is:

a. percolation

b. infiltration

c. irrigation

d. drainage

Explanation: This is the fundamental definition of irrigation in agricultural engineering.

34. A practice to minimize the effect of raindrop erosion.

a. mulching

b. contour farming

c. terracing

d. corrugation

Explanation: Mulching provides a protective cover that absorbs the kinetic energy of raindrops, preventing the detachment of soil particles.

35. Applying a small quantities of water through a network of tubing is otherwise known as:

a. drip irrigation

b. trickle irrigation

c. emitter irrigation

d. any of the above

Explanation: Drip, trickle, and emitter irrigation are all synonyms for localized irrigation systems.

36. Water that moves freely and drains out of the soil is:

a. hygroscopic water

b. capillary water

c. gravitational water

d. any of the above

Explanation: Gravitational water is the moisture that occupies the macro-pores and drains away due to gravity after a rain or irrigation event.

37. It is the most elaborate method of computing potential evapotranspiration.

a. Blaney-Criddle

b. Jenssen-Haise

c. Hargreaves

d. Penman

Explanation: The Penman (or Penman-Monteith) method is the most complex as it considers radiation, temperature, humidity, and wind speed.

38. If a soil is compacted:

a. its moisture content decrease

b. its porosity remains the same

c. its nutrient content diminishes

d. its bulk density increase

Explanation: Compaction reduces pore space, meaning the same mass of soil occupies less volume, which increases the bulk density.

39. The moisture content of the soil when the tension is 1/3 atmosphere.

a. field capacity

b. saturation point

c. wilting point

d. wilting coefficient

Explanation: Field Capacity is generally defined at 1/3 bar (0.33 atm) for loam/clay soils and 1/10 bar for sandy soils.

40. It is the measure of the difference in ground level between two places in a field is referred to as a percentage. It is the number of meters difference in elevation for each 100 m of horizontal distance.

a. velocity

b. discharge

c. land slope

d. side slopes

Explanation: Land slope (%) = (Vertical Rise / Horizontal Run) * 100.

41. Groundwater as a source of water for plant growth, thru capillary action, is effective only if the ground water is:

a. above the root zone

b. way below the root zone

c. within the depth from which the major needs of the plants are extracted

d. all of the above

Explanation: Capillary rise can contribute to crop water needs only if the water table is close enough to the root zone for the soil's capillary forces to lift water into the active rooting depth.

42. The best way of managing a farm with high water table to obtain optimum yield:

a. frequent application of light irrigation through sprinklers during the growing season

b. application of heavy sprinkler irrigation during the rainy season

c. application of large amount of irrigation water by a surface method during the growing season

d. non-application of water during the entire period growing season

Explanation: In areas with a very high water table, the upward capillary movement of water often provides sufficient moisture to meet the crop's consumptive use without supplemental irrigation.

43. The quotient of the weight of a volume of dry soil including air space and weight of an equal volume of water is:

a. Apparent specific gravity

b. real specific gravity

c. porosity

d. none of the above

Explanation: Apparent Specific Gravity (ASG), also known as bulk specific gravity, considers the bulk volume of the soil (solids + pores), whereas real specific gravity considers only the soil solids.

44. Moisture content present in the soil after gravitational water has been removed is called:

a. Wilting point

b. field capacity

c. unavailable moisture

d. none of the above

Explanation: Field Capacity (FC) is the moisture level reached after free-draining gravitational water has left the macro-pores, usually 2-3 days after heavy rain or irrigation.

45. 75% of available moisture is called:

a. readily available moisture

b. hygrospic water

c. permanent wilting point

d. none of the above

Explanation: Readily Available Moisture (RAM) is the portion of Available Moisture (AM) that plants can extract without experiencing water stress, typically cited as 75% in many Philippine ABE references.

46. The lateral movement of water in the soil:

a. seepage

b. drainage

c. irrigation

d. flooding

Explanation: Seepage refers to the slow movement of water through small cracks or pores in the soil, typically in a lateral or horizontal direction.

47. The mass per unit volume of the particles is:

a. specific gravity

b. porosity

c. soil density

d. void ratio

Explanation: Soil density (specifically particle density) is the mass of soil solids per unit volume of the solids.

48. The quantity expressing the ratio of the volume of pores to the volume of solid is:

a. Void ratio

b. porosity

c. specific gravity

d. soil density

Explanation: Void ratio (e) is defined as the volume of voids divided by the volume of solids, whereas porosity (n) is the volume of voids divided by the total volume.

49. Water held tightly to the surface of soil particle by adsorption forces is:

a. capillary water

b. hygroscopic water

c. soil water

d. gravitational water

Explanation: Hygroscopic water forms a thin film around soil particles and is held so tightly (adsorption) that it is unavailable to plants.

50. A conveyance structure used to turn conduits of varying sizes and shapes:

a. cut off

b. transition

c. weir

d. chute

Explanation: A transition is a structure designed to change the cross-section of a channel gradually to minimize head loss.

51. A surface irrigation method where a much smaller area is enclosed by levees:

a. trickle irrigation

b. drip irrigation

c. basin flooding

d. flood routing

Explanation: Basin irrigation involves surrounding a flat area of land with low earth ridges (levees) and quickly filling it with water.

52. It also refers to consumptive use by the crops:

a. evapotranspiration

b. water circulation

c. saturation vapor pressure

d. osmosis

Explanation: Consumptive use is the sum of water transpired by plants and evaporated from the adjacent soil or water surfaces.

53. A concept used to evaluate the losses of water during irrigation from the time leaves that source to the point of use:

a. irrigation efficiency

b. drainage efficiency

c. discharge flow rated

d. none of the above

Explanation: Irrigation efficiency measures how much of the water diverted from the source actually reaches and is stored in the root zone.

54. Ground water as source of water for plant growth through capillary action, is effective only if ground water is:

a. Above the rootzone

b. within the depth from which the major needs of the plants are extracted

c. Way below the rootzone

d. none of the above

Explanation: Effective capillary supply requires the water table to be near the active root zone.

55. The most simple form of open channel flow computation is:

a. unsteady uniform flow

b. steady uniform flow

c. steady non-uniform flow

d. unsteady non-uniform flow

Explanation: Steady uniform flow is the simplest hydraulic condition where discharge and depth remain constant over time and distance.

56. It is the soil moisture allowable depletion of the most crops:

a. 50%

b. 20%

c. 80%

d. 100%

Explanation: A 50% Management Allowed Depletion (MAD) is the standard threshold used to trigger irrigation for most upland crops.

57. The speed at which water flows in channel is:

a. Velocity

b. Discharge

c. run-off

d. volumetric flow

Explanation: Velocity is the distance traveled by water per unit of time (e.g., m/s).

58. It is equal to the cross-sectional area times the velocity of flow.

a. velocity

b. discharge

c. run-off

d. volumetric flow

Explanation: Discharge (Q) = Area (A) x Velocity (V), according to the continuity equation.

59. The water content of the soil between field capacity and wilting point is:

a. available moisture

b. plasticity index

c. allowable deficit

d. hygroscopic water

Explanation: Available moisture is the range of water that plants can physically pull from the soil matrix.

60. The time needed for water to infiltrate into the soil, depending on the depth of water and the soil type is called:

a. infiltration rate

b. irrigation rate

c. capillary

d. surface tension

Explanation: Infiltration rate is the velocity at which water enters the soil, usually measured in mm/hr.

61. The soil characteristic determining the maximum rate at which water can enter the soil under specific conditions, including the presence of excess water is:

a. infiltration

b. infiltration rate

c. capillary

d. surface tension

Explanation: This defines the soil's capacity to absorb water.

62. Rate of the bulk density to the density of water:

a. oven dry weight

b. App. specific gravity

c. soil volume

d. porosity

Explanation: Apparent Specific Gravity (ASG) is the ratio of the bulk density of soil to the density of water.

63. In open channel, the term A/P is know as:

a. hydraulic gradient

b. hydraulic radius

c. hydraulic conductivity

d. hydraulics

Explanation: Hydraulic Radius (R) is the ratio of the cross-sectional area (A) to the wetted perimeter (P).

64. A closed conduit usually circular, square or rectangular in cross section, used for conveying water across and under an elevated roadway, embankment of dikes?

a. gate

b. culvert

c. canal

d. drop

Explanation: Culverts are common drainage structures used to allow water to pass under obstacles like roads.

65. A device used to control the flow of water to, from or in a pipeline.

a. inlet

b. gate

c. weir

d. flume

Explanation: Gates (or valves) are used to regulate or shut off the flow of water in irrigation systems.

66. An appurtenance to the pipeline which permits the passage of air to or from the pipeline.

a. surge

b. water hammer

c. vent

d. gate

Explanation: Vents are necessary to prevent vacuum formation or air-locking within a pipeline.

67. Barrier constructed to hold water back and raise its level.

a. channel

b. dam

c. well

d. weir

Explanation: A dam is a large-scale barrier, while a weir is a smaller overflow structure. Both raise water levels.

68. It is the combined process of evaporation from the soil and transpiration from the plants:

a. evaporation

b. transpiration

c. evapo-transpiration

d. condensation

Explanation: Evapotranspiration (ET) represents the total water loss to the atmosphere from a cropped area.

69. The volume of water flowing each second, measured in cubic meters per second is:

a. stream

b. discharge

c. velocity

d. cross sectional area

Explanation: Discharge (Q) is the volumetric flow rate.

70. The frequent, slow application of water to the specific roootzone of the plant is called:

a. Sub-irrigation

b. sprinkler irrigation

c. drip irrigation

d. flooding

Explanation: Drip (or trickle) irrigation is the most water-efficient method as it targets the root zone directly.

71. Refers to the number of days between irrigation during periods without rainfall.

a. irrigation method

b. irrigation period

c. irrigation frequency

d. irrigation efficiency

Explanation: Irrigation frequency is the time interval between two consecutive irrigation applications.

72. A property associated with surface tension of liquid & manifested in the rise and fall of liquids in small diameter tubes.

a. conduction

b. cavitation

c. capillary

d. condensation

Explanation: Capillarity is driven by the forces of adhesion and surface tension.

73. Amount of rainfall retained in the rootzone.

a. consumptive use

b. percolation

c. seepage

d. effective rainfall

Explanation: Effective rainfall is the portion of total precipitation that is stored in the root zone and can be used by the plant.

74. It is used to divide & distribute the flow of water at desired direction usually placed or built with main farm ditch to divert H2O to supplementary farm ditches.

a. spill way

b. turn out

c. flumes

d. division box

Explanation: A division box is a structure used to split the flow of water into two or more smaller channels.

75. A notch of regular form through which the irrigation stream is made to flow & built as either portable or stationary structures is called:

a. Orifice

b. Parshall flume

c. weir

d. dam

Explanation: Weirs are used to measure the flow of water in open channels.

76. For the most efficient circular section, semi-circle, the hydraulic radius is equal to:

a. 1/4 its radius

b. its radius

c. 1/2 its radius

d. 1/4 its radius

Explanation: For a full or semi-circular pipe, R = (Area/Perimeter) = (πr²/2) / (πr) = r/2.

77. The soil characteristic determining the max. rate @ which water enters the soil under specific condition including the presence of excess water is:

a. capillary

b. surface tension

c. infiltration

d. infiltration rate

Explanation: The infiltration rate is the velocity at which water enters the soil. When soil is in continuous contact with excess water at the surface, the maximum rate at which it can absorb that water is defined as its infiltration capacity.

78. The mass per unit volume of the soil particle is:

a. porosity

b. void ratio

c. soil density

d. specific gravity

Explanation: Soil density (specifically particle density) is the mass of soil solids per unit volume of the solids.

79. The amount of H2O used in producing crop is:

a. H2O holding capacity 

b. Critical growth storage

c. rooting characteristics

d. percolation

Explanation: The technical term for water "used" is Consumptive Use.

80. H2O that moves freely and drains out of the soil is:

a. gravitational

b. capillary

c. S.I.A.

d. hygroscopic

Explanation: Gravitational water is the free water that moves into, through, or out of the soil under the influence of gravity. It typically occupies the larger macropores and drains away quickly after rain or irrigation, often reaching the groundwater table. Because it moves so rapidly, it is generally not available for plant use.

81. The direct attraction of similar molecules/ molecular attraction between similar molecules:

a. collision

b. attraction

c. repulsion

d. cohesion

Explanation: Cohesion is the force of attraction between the same type of molecules (like water to water), while adhesion is between different types (like water to soil).

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