1. When the water level in the pipe drops below the upper edge of the pipe and the conduit controls, the flow becomes:
a. weir flow
b. orifice flow
c. open channel flow
d. pipe flow
Explanation: When a conduit is not flowing full, the water surface is at atmospheric pressure, making it an open channel flow.
2. The rate of vertical water movement through the soil at saturated condition is:
a. infiltration rate
b. depletion rate
c. percolation rate
d. soil permeability
Explanation: Percolation refers specifically to the downward movement of water through the soil profile under saturated conditions.
3. A barrier placed in a stream to constrict the flow of water and cause it to fall over a crest, usually used to measure discharge:
a. flume
b. weir
c. gabion
d. staff gage
Explanation: A weir is a notch or obstruction in a channel over which water flows to measure discharge.
4. A hydraulic jump is a classic example of this type of flow:
a. Unsteady flow
b. Uniform Flow
c. Rapidly Varied flow
d. Critical flow
Explanation: A hydraulic jump occurs when liquid at high velocity discharges into a zone of lower velocity, characterized by a rapid change in depth over a short distance.
5. The soil property which describes the ability of the soil to transmit water:
a. hydraulic conductivity
b. matric potential
c. percolation rate
d. infiltration rate
Explanation: Hydraulic conductivity is the measure of a soil's ability to transmit water through its pores.
6. What is the effect of the presence of extensive vegetation in a watershed?
a. reduce peak runoff rates
b. increases infiltration capacity
c. both a and b
d. none of the above
Explanation: Vegetation reduces peak flow by increasing surface roughness/time of concentration and improves infiltration via root penetration.
7. Type of rainfall caused by the upward lifting of the air mass due to a mountain:
a. Convective rainfall
b. Frontal rainfall
c. Orographic rainfall
d. Cyclonic rainfall
Explanation: Orographic rainfall is triggered by topographical barriers (mountains) forcing moist air to rise and cool.
8. What do you call the mountain side, with reference to the wind direction, in which the air mass passing through it is cold and dry?
a. wayward
b. windward
c. Trade wind
d. Leeward
Explanation: The leeward side is the side sheltered from the wind, where air is dry due to moisture loss on the windward side.
9. It is the natural or synthetic hydrograph for one unit of direct runoff from the catchment in a specified unit of time:
a. basic hydrograph
b. unit hydrograph
c. design hydrograph
d. runoff hydrograph
Explanation: By definition, a unit hydrograph is the direct runoff hydrograph resulting from one unit of effective rainfall applied uniformly over the basin.
10. Graphical representation of instantaneous runoff against time:
a. hydrograph
b. monograph
c. log-probability graph
d. hytograph
Explanation: A hydrograph plots discharge (runoff) over time. A hyetograph plots rainfall intensity over time.
11. The capacity of rainfall (precipitation) to effect the detachment and transport of soil particles:
a. erodibility
b. effectivity
c. erosivity
d. conductivity
Explanation: Rainfall erosivity (often denoted by 'R' in the USLE) represents the potential of rain to cause erosion based on intensity and energy.
12. Removal of soil by water from small but well-defined channels when there is concentration of overland flow:
a. stream channel erosion
b. rill erosion
c. gully erosion
d. sheet erosion
Explanation: Gully erosion occurs when rills are enlarged by concentrated flow, creating larger channels that cannot be smoothed out by normal tillage.
13. Structured device designed to hold a pool of water to cushion the impact and retard the flow of falling water as from an overflow weir, chute or drop:
a. sill
b. apron
c. stilling basin
d. pond
Explanation: A stilling basin is a structure designed to dissipate kinetic energy and prevent downstream erosion.
14. Uniform removal of soil in thin layers from the sloping land resulting from the overland flow:
a. rill erosion
b. sheet erosion
c. coastal erosion
d. splash erosion
Explanation: Sheet erosion is the removal of a relatively uniform layer of soil from the land surface by raindrop splash and runoff.
15. What law prevails in air masses in the atmosphere that for every drop in pressure there is a corresponding decrease of temperature, inducing precipitation?
a. Law of Conservation of Mass
b. Avogadro’s Law
c. Law of Conservation of Energy
d. Ideal Gas Law
Explanation: The Ideal Gas Law (PV=nRT) explains adiabatic cooling: as air rises and expands (pressure drops), temperature decreases.
16. It is the time required for water to flow from the most remote point of the watershed to the outlet:
a. time to peak
b. recession time
c. lag time
d. time of concentration
Explanation: Time of concentration is the time needed for the entire watershed to contribute to the runoff at the outlet.
17. When is the best/recommended time to sample sediment load in the stream?
a. Intermittent flow
b. Peak flow
c. Base flow
d. Perennial flow
Explanation: Sediment transport is highest during peak flow events; sampling then provides the best data on the sediment rating curve.
18. In the current meter velocity equation V = a + bN, what does 'b' signify?
a. proportionality constant
b. starting constant
c. bed slope
d. number of revolutions
Explanation: In the linear regression of a current meter, 'b' is the slope (proportionality constant) and 'a' is the starting constant/friction factor. (Correcting original provided key).
19. In discharge measurement, the readings in a staff gage are useless without this:
a. synthetic hydrograph
b. unit hydrograph
c. rating curve
d. matching curve
Explanation: A staff gage only measures depth (stage). You need a stage-discharge relationship (rating curve) to convert that depth into a flow rate.
20. In the Soil Conservation method (curve number method), if the Curve number is 100, this indicates that:
a. rainfall = runoff
b. runoff = 0
c. rainfall is less than runoff
d. rainfall is highly erosive
Explanation: A CN of 100 represents a completely impervious surface where all precipitation becomes runoff.
21. A supercritical flow is a flow condition where:
a. Fr = 1
b. Fr > 1
c. Fr < 1
d. Fr > 4000
Explanation: Froude number (Fr) > 1 defines supercritical flow, where gravity waves cannot move upstream.
22. The rate of decrease of temperature with the increase in elevation is called:
a. updraft
b. convection rate
c. lapse rate
d. deflection rate
Explanation: The environmental lapse rate is the vertical rate of temperature change with height.
23. A type of cropping system wherein different crops are planted in an area one after the other each season:
a. strip cropping
b. mixed cropping
c. cropping pattern
d. relay cropping
Explanation: Relay cropping is a sequence of crops where the next is planted before the previous is harvested. (Correction: Sequential cropping is a better general term, but in context, relay fits the sequence).
24. Using the float method in determining the velocity of water in a channel, the float velocity in relation to the average water velocity is:
a. equal to the avg. water velocity
b. less than the avg. water velocity
c. greater than the avg. water velocity
d. no relation at all
Explanation: Surface floats travel faster than the average flow, requiring a float coefficient (usually 0.8–0.9) to estimate average velocity.
25. The USLE is a method of computing soil erosion. What type of soil erosion does it estimate?
a. sheet erosion only
b. sheet, rill and gully erosion
c. sheet and rill erosion only
d. all types of erosion
Explanation: The Universal Soil Loss Equation (USLE) is designed to predict long-term average annual soil loss from sheet and rill erosion.
26. A type of terrace usually used for 9-24% slope characterized by breaking the slope at certain intervals by a ridge and a flat portion to trap run-off:
a. Bench terrace
b. Broad-based terrace
c. Zingg terrace
d. Manning’s terrace
Explanation: Broad-based terraces consist of a ridge and a channel constructed over the slope to reduce slope length and intercept runoff.
27. A storm occurred in two similar watersheds, Glads and Karl. Glads is long/slender; Karl is short/wide. Which will experience the earliest peak flow?
a. Karl
b. The same
c. Glads
d. Neither Karl nor Glads
Explanation: Compact (wide) watersheds typically have a shorter time of concentration than elongated ones, leading to earlier peak flows.
28. Type of flow wherein the discharge or flow in a prismatic channel is constant with respect to time:
a. laminar flow
b. uniform flow
c. steady flow
d. critical flow
Explanation: Steady flow is defined by the property that fluid parameters (velocity, depth) at any point do not change with time.
29. Type of sediment load characterized as sediments that are sometimes stationary or sometimes carried by the water along the stream:
a. Saltating load
b. Bed load
c. Temporary load
d. Suspended load
Explanation: Saltation involves particles that bounce along the bed, intermittently contacting and being carried by the stream.
30. In frequency analysis, what process is governed by chance and time-dependent?
a. Deterministic Process
b. Probabilistic Process
c. Stochastic Process
d. Hydrolistic Process
Explanation: A stochastic process is a random process that evolves over time, which is the basis for hydrologic frequency modeling.
31. It is the ratio of the peak runoff rate to the rainfall intensity:
a. Drainage coefficient
b. Discharge coefficient
c. Runoff coefficient
d. Recharge coefficient
Explanation: The runoff coefficient (C in Q=CiA) represents the proportion of rainfall that becomes direct runoff.
32. Particle density is the ratio of mass of the dry soil to the:
a. Soil volume (volume of solids)
b. pore volume
c. bulk volume
d. Air-filled pore volume
Explanation: Particle density is the mass per unit volume of the soil particles only (excluding pore space).
33. The difference between field capacity and permanent wilting point:
a. available moisture
b. capillary water
c. both a and b
d. none of the above
Explanation: Available moisture (or water) is the range of water that plants can extract from the soil.
34. When the water level in an orifice drops below the upper edge of the orifice, the flow becomes:
a. weir flow
b. open channel flow
c. orifice flow
d. pipe flow
Explanation: Once the free surface falls below the top of the opening, it behaves as a weir.
35. What is the theoretical flow velocity in an orifice where the free water surface is 120 cm above the center of the orifice? (V = sqrt(2gh))
a. 48.5 m/s
b. 3.50 m/s
c. 2.15 m/s
d. 4.85 m/s
Explanation: V = sqrt(2 * 9.81 * 1.20) = sqrt(23.544) ≈ 4.85 m/s.
36. The recommended pressure variation in the lateral between the first and the last sprinkler is:
a. 5%
b. 10%
c. 15%
d. 20%
Explanation: To ensure uniform distribution, pressure variation in sprinkler laterals is generally kept below 20%.
37. The rate at which water moves through the soil profile is called:
a. soil hydraulic conductivity
b. infiltration rate
c. percolation rate
d. soil permeability
Explanation: Percolation rate is the speed at which water moves through the soil profile after it has infiltrated the surface.
38. The soil property which describes the ability of the soil to transmit water:
a. soil hydraulic conductivity
b. soil matric potential
c. percolation rate
d. hydraulic gradient
Explanation: (Duplicate of Q5). Hydraulic conductivity measures the ease with which soil pores permit water movement.
39. The soil property which is not affected by tillage and soil management but is dependent on the soil mineralogy and organic matter content:
a. Bulk density
b. Particle density
c. porosity
d. void ratio
Explanation: Particle density (often assumed 2.65 g/cm³) depends on the density of the soil particles themselves, not their arrangement.
40. Water flows from a region with higher moisture content to a region with lower moisture content. This statement is:
a. Always true
b. Always false
c. False if soil is homogeneous
d. none of the above
Explanation: Water flows from regions of higher total potential (energy) to lower potential, not necessarily higher moisture content.
41. An aquifer in which the groundwater has a free water surface open to the atmosphere:
a. unconfined
b. semi-confined
c. confined
d. none of the above
Explanation: An unconfined (or water-table) aquifer has no upper confining layer, allowing the water table to respond directly to atmospheric pressure.
42. A hydrograph shows the relationship with time of:
a. flow velocity
b. flow depth
c. flow discharge
d. none of the above
Explanation: By definition, a hydrograph is a plot of flow discharge (e.g., cubic meters per second) against time.
43. The best hydraulic section of a canal is characterized by:
a. minimum area for a given discharge
b. least wetted perimeter for a given area
c. applicable only to non-erodible channel
d. all of the above
Explanation: The best hydraulic section minimizes friction by minimizing the wetted perimeter for a required cross-sectional area.
44. The coefficient of discharge for a weir includes correction for the effects of:
a. physical characteristics of the weir
b. acceleration due to gravity
c. both a and b
d. none of the above
Explanation: The discharge coefficient accounts for empirical factors like viscosity, contraction, and weir geometry that theory alone doesn't cover.
45. It is the total suction head at the suction nozzle minus the vapor pressure at the pumping temperature:
a. net positive suction head
b. total dynamic head
c. static head
d. pressure head
Explanation: NPSH (available) is the absolute pressure head at the suction side minus the vapor pressure of the liquid, critical for preventing cavitation.
46. The removal of soil by water from small but well-defined channels or streamlets when there is a concentration of the overland flow:
a. sheet erosion
b. rill erosion
c. gully erosion
d. streambank erosion
Explanation: Rill erosion creates tiny, shallow channels that can be smoothed by regular farm equipment, unlike gullies.
47. A type of drainage system where laterals meet the main line at only one side:
a. random
b. natural
c. gridiron
d. herringbone
Explanation: A gridiron layout has laterals on one side of the main; a herringbone layout has them on both sides.
48. In water flow through culverts, if the inlet is not submerged and the inlet controls the flow, the flow is:
a. weir flow
b. orifice flow
c. open channel flow
d. pipe flow
Explanation: When inlet-controlled and unsubmerged, the culvert behaves like a weir.
49. When the water must be conveyed under the natural or artificial drainage channel, the structure used is:
a. chute
b. siphon
c. inverted siphon
d. drop
Explanation: An inverted siphon is a closed conduit that carries water under an obstacle like a road or stream using pressure.
50. It is the ratio of the dry weight of soil particles to the weight of an equal volume of water:
a. real specific gravity
b. bulk density
c. particle density
d. apparent specific gravity
Explanation: Specific gravity (real) is the ratio of the density of solid particles to the density of water. (Note: "Particle density" is often synonymous but specific gravity is the formal dimensionless ratio).
51. 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
Explanation: Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away (gravitational water removed).
52. 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
Explanation: An inverted siphon is a closed conduit used to convey water under pressure across a depression or beneath an obstacle.
53. The International Soil Science Society (ISSS) 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
Explanation: According to the ISSS classification, sand particles range from 0.02 mm to 2.0 mm in diameter.
54. A subsurface drain system wherein laterals join the submain on both sides alternately:
a. gridiron
b. herringbone
c. parallel drain system
d. double main system
Explanation: The herringbone pattern is characterized by laterals entering the main line at an angle from both sides.
55. 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
Explanation: Darcy's Law is Q = K * A * (dH/dL), where flow is proportional to conductivity (K) and inversely proportional to length (L).
56. 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
Explanation: Porosity is defined as the fraction of the total volume of soil occupied by pores (voids).
57. 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
Explanation: Hygroscopic water is tightly held to soil particle surfaces by adhesion and requires significant heat to remove.
58. It refers to the composite parts of the irrigation system that divert water from natural bodies of water such as rivers, streams, lakes:
a. main canal
b. diversion dam
c. irrigation structures
d. headworks
Explanation: Headworks constitute the structures at the source (diversion, intake, etc.) that manage the entry of water into the irrigation system.
59. It is the measure of the amount of water that the soil will retain against a tension of 15 atmospheres (approximately):
a. permanent wilting point
b. field capacity
c. available moisture
d. readily available moisture
Explanation: Soil moisture content at a suction of 15 bars (atmospheres) is the standard definition for the Permanent Wilting Point. 
60. The localized lowering of the static or piezometric water level due to pumping:
a. groundwater decline
b. draw down
c. subsidence
d. depression
Explanation: Drawdown is the distance between the static water level and the pumping water level in a well.
61. It is a geologic formation which transmits water at a rate insufficient to be economically developed for pumping:
a. aquifer
b. aquiclude
c. aquifuge
d. aquitard
Explanation: An aquiclude (or aquitard) contains water but does not transmit it fast enough for economic use.
62. An artesian well is a:
a. hand-pumped well
b. free-flowing well
c. well tapping a confined aquifer
d. well tapping an unconfined water
Explanation: While an artesian well taps a confined aquifer, its defining characteristic as a "flowing" well is that the piezometric surface is above ground level.
63. If an irrigation system can irrigate a farm in 5 days, the irrigation period is:
a. indeterminate
b. 5 hours
c. 5 days
d. 10 hours
Explanation: Irrigation period is the total time allowed to cover the entire designated area with one application of water.
64. If the impeller speed of a centrifugal pump is increased from 1800 to 2340 rpm, the resulting power will be how many times the original? (Power ratio = (N2/N1)^3)
a. 1.690
b. 2.197
c. 1.091
d. 1.140
Explanation: (2340/1800)^3 = (1.3)^3 = 2.197.
65. An application rate of 1 mm/day is equal to approximately:
a. 0.116 liters per second per hectare
b. 0.044 liters per hour
c. both a and b
d. neither a nor b
Explanation: 1 mm/day over 1 hectare = 10 m³/day = 10,000 L / 86,400 s ≈ 0.1157 L/s.
66. The crop water requirement minus the effective rainfall:
a. farm water requirement
b. irrigation water requirement
c. consumptive use
d. non-consumptive use
Explanation: Irrigation Requirement (IR) = Crop Water Requirement (CWR) - Effective Rainfall (ER).
67. An opening with a closed perimeter through which water flows:
a. flume
b. pipe
c. weir
d. orifice
Explanation: An orifice is an opening with a closed perimeter (e.g., circular, rectangular) through which fluid flows.
68. Scobey’s equation for friction head loss in pipes states that the friction loss is inversely proportional to:
a. length of pipe
b. inside diameter of pipe
c. discharge of pipe
d. outside diameter of pipe
Explanation: Scobey's formula generally shows friction loss increases as diameter decreases; thus it is inversely proportional to the diameter.
69. Difference in moisture content of soil between field capacity and permanent wilting point:
a. available moisture
b. readily available moisture
c. irrigation water requirement
d. saturation capacity
Explanation: Available Water Holding Capacity (AWHC) is defined as the difference between field capacity and the permanent wilting point.
70. The sum total of water lost in a given area through transpiration, evaporation, and for building plant tissues:
a. Consumptive use
b. Deep percolation
c. runoff
d. seepage
Explanation: Consumptive use (evapotranspiration) is the total water used by plants plus water evaporated from the soil/surfaces.
71. 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 water held by surface tension in the soil pores.
72. Small Water Impounding Management (SWIM) Projects generally have structural heights not more than:
a. 45 m
b. 50 m
c. 30 m
d. 100 m
Explanation: SWIM projects are categorized as small-scale dams usually under 30 meters.
73. 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 limited by atmospheric pressure to practical suction lifts of about 6–7 meters.
74. The moisture content of the soil when the tension is near zero (or at field saturation):
a. saturation point
b. wilting coefficient
c. field capacity
d. wilting point
Explanation: Saturation point occurs when all soil pores are filled with water.
75. What is the 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 is the general term for water held within soil pores, including capillary water.
76. 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 throughflow) is the lateral movement of water through the unsaturated soil profile toward a stream.
77. What is the term for the time required for the rate of surface runoff and the rate of rainfall to reach an equilibrium (where the entire watershed contributes)?
a. Run-off coefficient
b. infiltration rate
c. overflow
d. time of concentration
Explanation: The time of concentration is the time needed for the most hydraulically remote point in the basin to contribute to the outlet flow. 
78. 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: The piezometric surface represents the pressure level of a confined aquifer.
79. What is the term for capillary water in the smaller pore surfaces of the soil?
a. Interception
b. depression storage
c. basin recharge
d. soil moisture
Explanation: Capillary water is a primary component of soil moisture stored within soil pores.
80. 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: As defined in Q76, this is interflow. 
81. What is the term for the time required for the rate of surface runoff to reach equilibrium with rainfall?
a. Run-off coefficient
b. infiltration rate
c. overflow
d. time of concentration
Explanation: This refers to the time of concentration.
82. 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: The piezometric surface represents the pressure level of a confined aquifer.
83. 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 is the amount of water which can be withdrawn without exceeding the recharge. 
84. 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 irregular terrain because it does not require land leveling.
85. Which is the best method of irrigation for row crops?
a. flooding
b. furrow
c. sprinkling
d. sub-irrigation
Explanation: Furrow irrigation is the standard for row crops.
86. Which method of irrigation has the best control of water supplied?
a. flooding
b. furrow
c. sprinkling
d. sub-irrigation
Explanation: Pressurized systems (sprinklers/drip) offer the best control over water application rates.
87. 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 connects the heights to which water rises in piezometers.
88. 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: Hydraulic Radius (Rh) = Area / Wetted Perimeter = (Ï€D²/4) / (Ï€D) = D/4. Thus, 12mm / 4 = 3 mm.
89. Bulk density of a soil sample (85 cc volume, 130 grams dry weight):
a. 1.53 g/cc
b. 1.75 g/cc
c. 1.25 g/cc
d. 1.4 g/cc
Explanation: Bulk Density = Mass / Volume = 130g / 85cc ≈ 1.53 g/cc
90. Percentage moisture by weight if wet sample is 145g and dry weight is 130g:
a. 12.5%
b. 10.5%
c. 11.5%
d. 9.5%
Explanation: ((145g - 130g) / 130g) * 100 ≈ 11.53%.
91. The discharge of first emitter in a dripped line is 12 li/h. What is the allowable minimum discharge in the last emitter?
a. 9.6 li/h
b. 10.8 li/h
c. 10.6 li/h
d. 9.8 li/h
Explanation: Per PAES, allowable discharge variation (q_min/q_max) for emitters is typically 80% (12 * 0.8 = 9.6).
92. Groundwater as a source of water for plant growth, through 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: Capillary rise can only provide water if the root zone is within the capillary fringe of the water table.
93. The best way of managing a farm with a high water table to obtain optimum yield:
a. Frequent application of high irrigation
b. Application of heavy sprinkler irrigation
c. Application of surface irrigation
d. Non-application of water during high-water table periods
Explanation: If a high water table is already providing adequate capillary water, supplemental irrigation can lead to waterlogging.
94. The sum total of head above the vapor pressure of the liquid being pumped at a given temperature:
a. net positive suction head
b. total dynamic head
c. pump static head
d. total static head
Explanation: This is the definition of NPSH.
95. The recommended variation in the lateral between the first and the last sprinkler:
a. 20%
b. 50%
c. 70%
d. 100%
Explanation: To maintain uniform application, pressure variation should not exceed 20%.
96. The rate at which water percolates through the soil surface:
a. Irrigation
b. Drainage coefficient
c. soil permeability
d. infiltration rate
Explanation: Infiltration rate refers specifically to the downward movement of water across the soil surface boundary.
97. 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 case where depth, velocity, and discharge remain constant along the channel length and over time.
98. The part of the dam that releases surplus flood water which cannot be contained in the reservoir:
a. freeboard
b. spillway
c. gates
d. weir
Explanation: A spillway is a structure designed to provide safe release of floodwater from a dam.
99. The most efficient trapezoidal cross-section:
a. width of the bottom = 2 * depth * tan(theta/2)
b. depth = twice the bottom
c. width of the bottom = 4x the depth
d. width of the top = 2x sum of sides
Explanation: A hydraulically efficient section minimizes the wetted perimeter. For a trapezoid, this occurs when the hydraulic radius is half the depth.
100. If a rectangular canal has a base of 0.65 m, what is the depth of flow when the hydraulic radius is equal to the area of flow?
a. 0.418 m
b. 4.18 m
c. 0.17 m
d. 1.7 m
Explanation: By setting the hydraulic radius formula (Area/Wetted Perimeter) equal to the Area formula (b*y), the variables cancel out to show that 1 = b + 2y. Solving for y with b=0.65 results in y ≈ 0.175 m.

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