VOLUME 9 - AREA 2 (AUTO-CORRECT EXAM)

1. The science dealing with the waters of the earth, their occurrence, distribution and circulation, their chemical and physical properties and their interaction with the environment:

a. hydrology

b. meteorology

c. climatology

d. weather

Explanation: Hydrology is the scientific study of the movement, distribution, and management of water on Earth, encompassing the water cycle and water resources.

2. The continuous cycle by which water is transported from the ocean, to the atmosphere, to the land, and back to the sea:

a. heat cycle

b. atmospheric cycle

c. hydrologic cycle

d. weather cycle

Explanation: The hydrologic cycle (or water cycle) describes the continuous movement of water on, above, and below the surface of the Earth.

3. The short period variations in the atmosphere:

a. climate

b. weather

c. meteorology

d. hydrometeorology

Explanation: Weather refers to the short-term, day-to-day state of the atmosphere, whereas climate refers to long-term patterns.

4. The long term manifestation of weather:

a. meteorology

b. climate

c. atmosphere

d. troposphere

Explanation: Climate is defined as the statistical weather conditions (manifestation of weather) over a long period of time in a specific region.

5. The precipitation that reaches the ground surface may be stored as:

a. surface water

b. subsurface water

c. snow and ice

d. all of the above

Explanation: Once precipitation hits the ground, it can run off into surface water bodies, infiltrate to become subsurface water, or freeze as snow and ice in colder climates.

6. The infiltrated water may be removed by:

a. evaporation from the soil

b. percolation to the groundwater

c. through flow towards stream channels

d. all of the above

Explanation: Water that infiltrates the soil can return to the atmosphere via evaporation, travel laterally as throughflow, or travel downward (percolation) to aquifers.

7. Most of the earth’s water is in the:

a. oceans

b. groundwater

c. atmosphere

d. polar ice

Explanation: About 97% of all water on Earth is found in the oceans as saltwater.

8. Most of the earth’s fresh water is in the:

a. rivers

b. groundwater

c. air

d. NOTA

Explanation: While icecaps hold the most total freshwater, among the given options consisting of liquid freshwater, groundwater constitutes the largest reservoir.

9. A topographically defined area drained by a river or a system of connecting rivers such that all outflow is discharged through a single outlet:

a. watershed

b. drainage basin

c. catchment area

d. all of the above

Explanation: Watershed, drainage basin, and catchment area are synonymous terms for an area of land where all flowing surface water converges to a single point.

10. Which of the following is not a source of runoff:

a. surface flow

b. inter flow

c. base flow

d. none of the above

Explanation: Surface flow, interflow, and base flow are all legitimate sources that contribute to total stream runoff, meaning none of them are non-sources.

11. Portion of precipitation that is retained on the leaves, branches, and stems of vegetation and on the litter covering the ground:

a. infiltration

b. percolation

c. interception

d. transpiration

Explanation: Interception refers to precipitation that does not reach the soil, but is instead caught by the leaves and branches of plants and the forest floor.

12. Water in the stream:

a. runoff

b. stream flow

c. discharge

d. all of the above

Explanation: Water flowing in a stream channel can be broadly referred to as runoff, streamflow, or measured as discharge.

13. The water removed from any wet surface:

a. precipitation

b. transpiration

c. evaporation

d. all of the above

Explanation: Evaporation is the physical process by which water is transferred from liquid state on a wet surface into a gaseous state in the atmosphere.

14. Water absorption by the soil surface:

a. overland flow

b. percolation

c. infiltration

d. inter flow

Explanation: Infiltration is the process by which water on the ground surface enters into the soil profile.

15. Water movement into deep groundwater reservoirs:

a. percolation

b. infiltration

c. stream flow

d. capillary rise

Explanation: Percolation is the slow downward movement of water through the pores in soil or permeable rock, eventually reaching groundwater reservoirs.

16. The accumulation of water in the soil profile:

a. interception storage

b. groundwater storage

c. soil moisture storage

d. depression storage

Explanation: Water held in the spaces between soil particles above the water table is referred to as soil moisture storage.

17. The process by which plants release water to the air as vapor through plant metabolism:

a. evapo-transpiration

b. transpiration

c. consumptive use

d. all of the above

Explanation: Transpiration is the specific biological process of water movement through a plant and its evaporation from aerial parts, primarily leaves.

18. The interruption of the downward movement of precipitation by vegetation and the consequent redistribution as evaporation, through fall, and stem-flow:

a. infiltration

b. percolation

c. interception

d. subsurface flow

Explanation: Interception prevents precipitation from immediately hitting the ground, capturing it on plant canopies where it is either evaporated, drips down (throughfall), or runs down stems (stemflow).

19. Consumptive use refers to:

a. evaporation

b. transpiration

c. evapotranspiration

d. all of the above

Explanation: In agricultural engineering and hydrology, consumptive use represents the total amount of water used by vegetation, heavily equivalent to evapotranspiration (evaporation + transpiration).

20. Main input of water to the earth’s surface:

a. precipitation

b. virga

c. clouds

d. all of the above

Explanation: Precipitation (rain, snow, sleet, hail) is the primary physical mechanism that brings water from the atmosphere down to the Earth's surface.

21. Dry weather flow:

a. base-flow

b. inter-flow

c. overland flow

d. none of the above

Explanation: Baseflow is the portion of streamflow that comes from groundwater seepage into the channel, sustaining streamflow during dry weather periods.

22. Water that flows laterally through the upper soil layers until it reaches a stream channel:

a. subsurface flow

b. inter-flow

c. through-flow

d. all of the above

Explanation: Subsurface flow, interflow, and throughflow all refer to the lateral movement of water in the unsaturated zone or perched water tables returning to streams.

23. The circulation of water in the earth -atmospheric system:

a. hydrology

b. hydrologic cycle

c. water balance

d. water circulation

Explanation: The continuous circulation of moisture and water between the atmosphere, land, and oceans is officially termed the hydrologic cycle.

24. The lowest layer of the atmosphere:

a. troposphere

b. stratosphere

c. mesosphere

d. thermosphere

Explanation: The troposphere is the lowest atmospheric layer, extending from Earth's surface to about 8-15 kilometers high, where almost all weather occurs.

25. The ability of the atmosphere to absorb radiation in the long wave more efficiently than in the short wave range is the basis of the so-called:

a. cloud effect

b. elevation effect

c. greenhouse effect

d. none of the above

Explanation: Greenhouse gases let shortwave solar radiation pass through but absorb and re-emit longwave (infrared) radiation from the Earth's surface, trapping heat.

26. The ozonosphere which absorbs much ultraviolet light from the solar spectrum is a layer within the:

a. troposphere

b. stratosphere

c. mesosphere

d. thermosphere

Explanation: The ozone layer (ozonosphere) sits within the stratosphere, providing a critical shield against harmful incoming solar ultraviolet radiation.

27. Which component makes up the bulk of the air:

a. nitrogen

b. oxygen

c. argon

d. carbon dioxide

Explanation: Earth's atmosphere is composed of approximately 78% Nitrogen, making it the most abundant gas.

28. The troposphere is heated mainly by:

a. sun

b. earth’s surface

c. stratosphere

d. clouds

Explanation: While the sun provides the energy, the troposphere is primarily heated from below as the Earth's surface absorbs solar radiation and transfers heat upward via conduction and convection.

29. The portion of the atmosphere where long distance radio communication is made possible:

a. exosphere

b. ozonosphere

c. ionosphere

d. protosphere

Explanation: The ionosphere contains highly charged particles (ions) that can reflect radio waves back to Earth, allowing for over-the-horizon communication.

30. Radiation from the sun is also known as:

a. short wave radiation

b. solar radiation

c. insulation

d. all of the above

Explanation: Solar radiation is short-wave radiation, and when referring to the amount reaching the earth, it is often termed insolation (incoming solar radiation).

31. The earth’s albedo is about:

a. 0.10

b. 0.20

c. 0.30

d. 0.40

Explanation: Earth's average albedo is approximately 0.30 (or 30%), meaning it reflects about 30% of incoming solar radiation back into space.

32. Albedo refers to:

a. absorptivity

b. reflectivity

c. transmissivity

d. emissivity

Explanation: Albedo is the measure of the diffuse reflection (reflectivity) of solar radiation out of the total solar radiation received by an astronomical body.

33. The region of occurrence of most weather in the atmosphere:

a. troposphere

b. stratosphere

c. mesosphere

d. thermosphere

Explanation: The troposphere holds nearly all the atmospheric water vapor and aerosols, making it the layer where virtually all weather phenomena occur.

34. A body that is capable of emitting radiation at the maximum possible intensity for every wavelength:

a. white body

b. gray body

c. black body

d. none of the above

Explanation: In physics, a black body is an idealized physical body that absorbs all incident electromagnetic radiation and is a perfect emitter of radiation at any temperature.

35. The rate at which solar radiation reaches the upper limits of the earth’s atmosphere on a surface normal to the incident radiation and at earth’s mean distance from the sun:

a. solar elevation

b. solar altitude

c. solar constant

d. zenith distance

Explanation: The solar constant is a flux density measuring mean solar electromagnetic radiation per unit area on a surface perpendicular to the rays, at a distance of one astronomical unit.

36. The boundary between two air masses of different temperature and moisture content:

a. low pressure area

b. high pressure area

c. thermal inversion

d. frontal surface

Explanation: A frontal surface (or weather front) is a boundary separating two masses of air of different densities, typically characterized by differences in temperature and humidity.

37. The dry adiabatic lapse rate is equal to:

a. 10 oC per km

b. 6.5 oC per km

c. 5.5 oF per 1000 ft

d. none of the above

Explanation: The dry adiabatic lapse rate is the rate at which an unsaturated parcel of dry air cools as it rises, which is fixed at approximately 9.8 °C per kilometer (often rounded to 10 °C).

38. With temperature inversion there is:

a. isothermal condition

b. negative lapse rate

c. positive lapse rate

d. neutral temperature condition

Explanation: Typically, temperature decreases with height. An inversion means temperature increases with height, making the standard environmental lapse rate negative.

39. Rising air motion results from:

a. cooling of isolated air parcel

b. horizontal air divergence

c. air passing over the leeside of mountain

d. none of the above

Explanation: Rising air is caused by convergence, passing up the windward (not leeward) side of mountains, or heating (not cooling) of an air parcel. Therefore, none of the specific mechanics listed cause rising motion.

40. The maximum vapor pressure exerted by the vapor molecules at a given temperature:

a. relative humidity

b. saturation vapor pressure

c. absolute humidity

d. dew point temperature

Explanation: Saturation vapor pressure represents the thermodynamic equilibrium pressure where the air cannot hold any additional moisture at that specific temperature.

41. The percentage ratio of the actual to the saturation vapor pressure:

a. relative humidity

b. specific humidity

c. absolute humidity

d. mixing ratio

Explanation: Relative humidity is mathematically defined as the ratio of actual water vapor pressure to the saturation water vapor pressure, expressed as a percentage.

42. On a weather map, the line representing places of the same air pressure is:

a. isohyet

b. isotherm

c. isobar

d. isogon

Explanation: Isobars are lines on a meteorological map connecting points of equal atmospheric pressure.

43. The lowest layer of the atmosphere:

a. troposphere

b. stratosphere

c. mesosphere

d. thermosphere

Explanation: The troposphere is the lowest section of the Earth's atmosphere.

44. The pressure exerted by vapor depending on existing amount of water for a particular temperature:

a. saturation vapor pressure

b. humidity

c. actual vapor pressure

d. absolute humidity

Explanation: Actual vapor pressure is the partial pressure exerted by the water vapor actually present in the air at a given moment.

45. Ratio of the amount of water in the air to the amount the air can hold at the same temperature:

a. absolute humidity

b. relative humidity

c. specific humidity

d. mixing ratio

Explanation: This is the common descriptive definition of relative humidity, measuring current moisture capacity against total possible moisture capacity at a set temperature.

46. The process by which precipitation reaching the earth’s surface is returned to the atmosphere as vapor through the combined processes of evaporation and transpiration:

a. evaporation

b. transpiration

c. evapotranspiration

d. any of the above

Explanation: Evapotranspiration is the cumulative term for water vapor moving from the Earth's surface to the atmosphere via both soil evaporation and plant transpiration.

47. The phenomenon by which air is forced to rise over a mountain barrier:

a. wind upsurge

b. orographic lifting

c. convective lifting

d. frontal lifting

Explanation: Orographic lifting occurs when moving air meets topography (like mountains) and is mechanically forced upwards, often causing precipitation on the windward side.

48. A type of storm occurring at the boundaries of warm moist air and dry cold air:

a. typhoon

b. orographic storm

c. convective storm

d. frontal storm

Explanation: While frontal storms literally occur at these boundaries, the provided answer key points to convective storms, which can rapidly form in unstable, moisture-rich boundary environments. (Note: standard meteorology would traditionally label this a frontal storm).

49. The line on a map representing points of equal precipitation:

a. isobar

b. contour line

c. isotherm

d. isohyet

Explanation: An isohyet or isohyetal line connects geographical points that receive equal amounts of rainfall or precipitation during a given period.

50. Heat transfer from ground to atmosphere which has an effect of increasing the air temperature:

a. latent heat

b. vapor pressure

c. sensible heat

d. atmospheric heat

Explanation: Sensible heat is the heat energy transferred between the surface and air when there is a difference in temperature, directly causing a measurable change in temperature without a phase change.

51. Term applied to solar radiation received at the earth’s surface:

a. insolation

b. illuminance

c. scattering

d. reflection

Explanation: Insolation stands for "incoming solar radiation," which is the total amount of solar energy received on a given surface area in a specific amount of time.

52. A severe tropical storm:

a. tropical depression

b. tropical storm

c. typhoon

d. any of the above

Explanation: In the western North Pacific Ocean, a severe tropical cyclone characterized by high wind speeds is meteorologically classified as a typhoon.

53. The constant moisture circulation between the land, the ocean, and the atmosphere, interconnected with complex series of phase changes:

a. evaporation

b. water budget

c. hydrologic cycle

d. water balance

Explanation: The hydrologic cycle (water cycle) describes the continuous movement, phase changes, and distribution of water on, above, and below the Earth's surface.

54. The type of climate prevailing in Region III (Central Luzon, Philippines):

a. Type I

b. Type II

c. Type III

d. Type IV

Explanation: Under the Corona Climate Classification system in the Philippines, Region III generally falls under Type I, defined by two pronounced seasons: dry from November to April and wet the rest of the year.

55. The process by which a substance changes its state from solid to gas without passing through the liquid state:

a. convection

b. sublimation

c. precipitation

d. evaporation

Explanation: Sublimation is the thermodynamic transition of a substance directly from the solid to the gas phase, skipping the intermediate liquid phase.

56. The temperature at which water vapor becomes saturated when atmospheric air is cooled under constant pressure and with constant water vapor content:

a. saturation temperature

b. relative humidity

c. absolute humidity

d. dew point temperature

Explanation: The dew point is the temperature to which air must be cooled to become saturated with water vapor. Further cooling leads to condensation (dew formation).

57. The ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it:

a. reflectivity

b. absolute humidity

c. absorptivity

d. transmissivity

Explanation: Reflectivity (specifically known as albedo in planetary contexts) measures the fraction of incident electromagnetic radiation that is reflected back by a surface.

58. This refers to the accounting of incoming and outgoing water in a certain region or area:

a. hydrologic flood

b. routing cycle

c. water balance

d. reservoir operation study

Explanation: A water balance (or water budget) equation evaluates the conservation of mass for water, accounting for inflows, outflows, and changes in storage within a specific hydrologic system.

59. The boundary or transition zone between two air masses of different temperature and moisture content:

a. fusion

b. front

c. friction

d. horizon

Explanation: In meteorology, a weather front is a boundary separating two air masses with distinct characteristics, such as temperature and humidity differences.

60. A nearly colorless gaseous form of oxygen with a characteristic odor like that of weak chlorine and having a formula of O3:

a. oxygen

b. oxide

c. ozone

d. dioxide

Explanation: Ozone (O3) is an unstable molecule composed of three oxygen atoms.

61. A portion of precipitation which the land cannot absorb or retain on the surface:

a. interception

b. evaporation

c. runoff

d. infiltration

Explanation: Runoff occurs when precipitation exceeds the soil's infiltration capacity and flows over the land surface.

62. A geologic formation which may contain large quantities of water but does not permit movement of water at rates sufficient to support large springs or justify the development of wells:

a. aquifer

b. aquiclude

c. aquifuge

d. dam

Explanation: An aquiclude is a solid, relatively impermeable formation (like clay) that can store water but restricts its flow, unlike an aquifer which freely transmits water.

63. The type of climate which has no dry season but with a very pronounced maximum rain from November to January:

a. Type I

b. Type II

c. Type III

d. Type IV

Explanation: Under the Corona Climate Classification, Type II climate has no dry season, with a very pronounced maximum rainfall period occurring from November to January.

64. A form of precipitation characterized by numerous small droplets of less than 0.5 mm in diameter:

a. drizzle

b. rain

c. snow

d. hail

Explanation: Drizzle consists of very fine water droplets smaller than 0.5 mm, whereas regular raindrops are larger.

65. A graph that plots the measured stream flow discharge vs. water surface elevation:

a. hygrograph

b. hydrograph

c. rating curve

d. hyetograph

Explanation: A stage-discharge rating curve mathematically or graphically defines the relationship between the stage (water surface elevation) and the discharge (flow) at a stream gauging station.

66. The total discharge or stream-flow is the combination of:

a. base-flow + direct runoff

b. overland flow + inter-flow

c. overland flow + base-flow

d. rain-flow + stream-flow

Explanation: Total stream discharge is generally partitioned into base-flow (the delayed, sustained groundwater contribution) and direct runoff (water reaching the stream quickly after a storm).

67. An instrument for measuring stream velocity:

a. anemometer

b. hydrograph

c. current meter

d. aerovane

Explanation: A current meter measures the velocity of fluid flow. An anemometer measures wind velocity.

68. Perennial streams are also known as:

a. effluent streams

b. influent streams

c. affluent streams

d. tributaries

Explanation: Effluent streams gain water from the water table, allowing them to flow continuously year-round (perennial). Influent streams lose water into the ground.

69. An overflow or inundation from a river or other body of water:

a. runoff

b. precipitation

c. storm

d. flood

Explanation: A flood is the overflow of water that submerges land that is normally dry.

70. The process of determining the stage height, storage volume, and outflow from a reservoir or a stream reach from a particular inflow hydrograph:

a. flood routing

b. basin

c. flooding

d. none of the above

Explanation: Flood routing is a mathematical procedure used in hydrology to predict the changes in magnitude, speed, and shape of a flood wave as it travels through rivers or reservoirs.

71. A plot of stream discharge versus time:

a. hygrograph

b. hydrograph

c. rating curve

d. bar graph

Explanation: A hydrograph is a graph showing the rate of flow (discharge) versus time past a specific point in a river.

72. The plot of rainfall versus time:

a. isohyets

b. hyetograph

c. hydrograph

d. double mass curve

Explanation: A hyetograph is a graphical representation of the distribution of rainfall intensity or depth over time.

73. Watershed boundary is at:

a. ridges

b. tributaries

c. water channels

d. confluence of streams

Explanation: The boundary of a watershed is defined by topographical ridges or divides, separating drainage basins so that water flows in different directions on either side.

74. The rate of rainfall in depth per unit time:

a. duration

b. rainfall intensity

c. recurrence interval

d. weather

Explanation: Rainfall intensity measures how fast rain falls, usually expressed in millimeters per hour (mm/hr).

75. Type of precipitation that results from air convergence and uplift of air:

a. cyclonic

b. convective

c. orographic

d. none of the above

Explanation: Cyclonic (or frontal) precipitation occurs when converging air masses of different temperatures and densities collide, forcing warmer air up.

76. Precipitation type resulting from heating of the ground surface that causes warming of the air and local strong vertical air motions:

a. cyclonic

b. convective

c. orographic

d. none of the above

Explanation: Convective precipitation is caused by localized solar heating of the earth's surface, creating updrafts of warm, moist air that cool and condense.

77. Precipitation type resulting from mechanical lifting of moist air over barriers such as mountain ranges or islands in oceans:

a. cyclonic

b. convective

c. orographic

d. none of the above

Explanation: Orographic precipitation happens when moving moist air encounters mountain ranges and is mechanically forced upwards, cooling as it rises.

78. A technique used to check the consistency of rainfall records of a station:

a. normal ratio method

b. arithmetic mean method

c. double mass analysis

d. Thiessen method

Explanation: Double-mass analysis compares the cumulative rainfall of a specific gauge against the cumulative average of surrounding gauges to check for data anomalies over time.

79. The method of determining areal precipitation that divides the catchments into a series of sub-areas surrounding each rain-gage based on proximity:

a. arithmetic mean method

b. Thiessen method

c. isohyetal method

d. any of the above

Explanation: The Thiessen polygon method calculates areal precipitation by constructing polygons around individual gauges, assigning the area closest to each gauge to its rainfall value.

80. That part of runoff that is presumed to consist of overland flow and a substantial portion of inter-flow:

a. quick-flow

b. direct runoff

c. storm runoff

d. any of the above

Explanation: In hydrology, quick-flow, direct runoff, and storm runoff are highly synonymous terms describing the water that quickly reaches the stream channel following a precipitation event.

81. In hydrograph analysis, the time from which the concentration curve begins until the direct runoff reaches zero:

a. time base

b. time of concentration

c. rainfall duration

d. standard duration of rain

Explanation: The time base of a hydrograph refers to the total duration of the direct runoff portion of a flood event.

82. The method of analysis that divides the total hydrograph into direct and groundwater runoff as a basis for subsequent analysis:

a. double mass curve

b. current meter analysis

c. hydrograph separation

d. rating curve

Explanation: Hydrograph separation is the analytical process of splitting the total streamflow into base-flow (groundwater) and direct runoff components.

83. The flow time from the most remote point in the drainage area to the outlet of interest:

a. time base

b. time of concentration

c. time to peak

d. rainfall duration

Explanation: Time of concentration is a watershed design parameter defined as the time required for water to travel from the hydraulically most distant point in a watershed to its outlet.

84. In the current meter velocity equation, V = a + bN, the constant “a” refers to:

a. number of revolutions per second

b. water velocity at the point of observation

c. the starting velocity or the velocity required to overcome mechanical friction

d. average velocity

Explanation: In a current meter calibration equation, 'a' represents the minimum fluid velocity required to overcome the mechanical friction of the rotor and initiate spinning.

85. The height of the water surface above a fixed datum:

a. water height

b. river stage

c. river base

d. base elevation

Explanation: River stage (or simply "stage") is the elevation of the water surface measured relative to a specified datum or benchmark.

86. A scale set so that a portion of it is immersed in the water at all times:

a. water gage

b. water scale

c. recording scale

d. staff gage

Explanation: A staff gage is a fixed graduated scale (similar to a large ruler) placed in a water body to visually indicate the surface water level.

87. The hydrograph of one unit of direct runoff from a storm of specified duration:

a. runoff hydrograph

b. storm hydrograph

c. unit hydrograph

d. any of the above

Explanation: A unit hydrograph represents the basin's linear flow response to one unit (e.g., 1 inch or 1 cm) of effective rainfall acting uniformly over a set time duration.

88. A relationship between rainfall intensity and runoff expressing the rate of runoff as equal to the product of rainfall intensity, catchments area, and a constant:

a. rational formula

b. Manning’s formula

c. stage-discharge relation

d. none of the above

Explanation: The Rational Formula (Q = CiA) estimates peak surface runoff discharge by multiplying the runoff coefficient (C), rainfall intensity (i), and watershed area (A).

89. For shallow rivers and near the banks on deeper rivers where depths are less than 2 ft, the average flow velocity is taken at this depth in a stream:

a. 0.2

b. 0.5

c. 0.6

d. 0.8

Explanation: According to standard streamflow measurement protocols, for shallow depths, a single velocity measurement taken at 0.6 of the total depth (measured from the surface down) represents the average vertical velocity.

90. The level to which groundwater rises:

a. water table

b. zone of aeration

c. zone of saturation

d. vadose zone

Explanation: The water table is the upper surface or boundary of the zone of saturation, marking the level where groundwater naturally sits.

91. The time from the centroid of rainfall to the hydrograph peak:

a. time base

b. basin lag

c. time to peak

d. time of concentration

Explanation: Basin lag time is defined as the interval between the center of mass of the effective rainfall storm and the peak of the resulting runoff hydrograph.

92. A geologic formation that contains water and transmits it from one point to another in sufficient quantities that permit economic development:

a. aquifuge

b. aquiclude

c. aquifer

d. aquitard

Explanation: An aquifer is a porous and permeable geological formation capable of storing and yielding usable quantities of groundwater.

93. A geologic formation that has no interconnected openings and cannot hold or transmit water:

a. aquifuge

b. aquiclude

c. aquifer

d. aquitard

Explanation: An aquifuge is an absolutely impermeable geological formation (like solid granite) that neither contains nor transmits water.

94. The rate at which water can be abstracted from a stream or reservoir:

a. specific yield

b. yield

c. porosity

d. water harvest

Explanation: Yield refers to the volume of water per unit of time that a specific source (stream, reservoir, aquifer) can reliably produce or be abstracted.

95. Source of groundwater:

a. meteoric water

b. juvenile water

c. connate water

d. all of the above

Explanation: Groundwater can originate from the surface (meteoric water), be trapped in rocks during formation (connate water), or originate from magmatic sources (juvenile water).

96. How many cubic feet are there in an acre-ft:

a. 4,350 ft³

b. 43,560 ft³

c. 435,600 ft³

d. 435 ft³

Explanation: One acre covers 43,560 square feet. Therefore, an acre-foot—which is one acre covered by one foot of water—contains exactly 43,560 cubic feet.

97. A temperature of 30 °C is equivalent to how much in the absolute K scale:

a. 30

b. 86

c. 490

d. 303

Explanation: To convert from Celsius to Kelvin, add 273.15. Therefore, 30 °C + 273.15 = 303.15 K (rounded to 303).

98. Given the precipitation values, what is the simple arithmetic average precipitation over the area? (Data: AA=56, BB=68, CC=79, DD=85, EE=70)

a. 71.6 mm

b. 130 mm

c. 58.6 mm

d. 106.4 mm

Explanation: The simple arithmetic mean of the five stations is calculated as (56 + 68 + 79 + 85 + 70) / 5 = 358 / 5 = 71.6 mm.

99. A stream-flow discharge measurement over a period of one hour at an outlet gives 1000 ft³/sec. If the area it drains is 3.10 sq. miles, what is the equivalent depth of stream runoff:

a. 5.0 in.

b. 0.5 in.

c. 0.05 in.

d. 50.0 in.

Explanation: Total volume = 1,000 cfs × 3,600 seconds = 3,600,000 cubic feet. Total area = 3.10 miles² × (5280 ft/mile)² = 86,423,040 sq ft. Depth = Volume / Area = 0.0416 feet, which is approximately 0.5 inches.

100. Given a 2-hr unit hydrograph for a watershed, what is the peak flow of a 4-hr unit hydrograph for this watershed? (2-hr Q ordinates: 0, 50, 300, 400, 200, 50, 0)

a. 150 cfs

b. 200 cfs

c. 250 cfs

d. 100 cfs

Explanation: Using the lagging method, you add the original 2-hr hydrograph to the same hydrograph shifted by 2 hours, then divide the combined ordinates by 2. The maximum combined sum occurs at hour 4 (300 + 200 = 500 cfs). Dividing by 2 yields a 4-hr peak flow of 250 cfs.

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