MSU-General Santos

Agricultural & Biosystems Engineering

Review 2023

Hydrology & Meteorology

Prepared By: ER Lapong
1. Which is not a problem caused by acid rain?

a. Soil acidity
b. Structure corrosion
c. Soil erosion
d. Structure erosion
e. water acidity

Answer: a. Soil erosion

2. Refers to an increase in the primary productivity
of any ecosystem caused by the increase of
chemical nutrients, typically compounds of N & P

a. Ecological succession
b. Eutrophication
c. Environmental degradation
d. Both a & b
e. All of the above

Answer: d. Both a & b

3. The atmospheric condition over a short
duration of time

a. Weather
b. Climate
c. Atmospheric zones
d. Atmospheric conditions
e. All of the above

Answer: a. Weather
Weather – atmospheric condition over a short duration,
particularly the combination of heat, moisture and wind
characteristics of the atmosphere in a day

Climate – the total weather condition of an area as

generalized over a long period of time, i.e. seasons,
years, decades
4. Which of the following affects weather or
climatic condition?

a. Position of the earth

b. Wind systems
c. Ocean currents
d. Land and water masses
e. All of the above

Answer: e. All of the above

Major factors affecting terrestrial climate:

1. Position of the earth

The earth’s declination, rotation, and revolution
affects incoming radiation, land temperature, length
of day and night and tides

2. Land and water masses

The geographic distribution of continents and
ocean affects regional temperature, precipitation,
wind direction and speed.
Major factors affecting terrestrial climate:

3. Surface features of the land

The large scale mountainous features of land
masses, i.e. altitude, depressions, mountain ranges
and other geographic features.

4. Wind systems and pressure belts

The general circulation of the atmosphere affects
pressure in the atmosphere and land and water
masses, and the development of weather
disturbances.
Position of the earth
Insolation – Incoming Solar Radiation (incoming sunlight)
Albedo – fraction of the incident radiation that is reflected by
an object

 An average of 1/3 (34%) of the insolation is reflected back,

19% absorbed by the atmosphere and 47% absorbed by
the earth’s surface.

Common albedo values:

snow = 0.81~
clouds = 0.17-0.81
forests = 0.03-0.10
dark dry sand = 0 – 0.18
Solstice and Equinox

Solstice – the period when the sun is farthest from the earth
(δ=23.450)

Equinox – sun’s position makes day and night equal

- sun is directly above the observer (δ=0)

  284  n 
  23.45 sin 360 
  365 
where: (-23.450 ≤ δ ≤ 23.450)
n = days of the year (Jan.1=1, Dec.31=365)
 * Days get * Nights get
longer shorter

* Days get
shorter * Nights get
longer
Spring Tide

• Stronger high and low tides

• During new and full moon (earth, moon and sun are
parallel or in-line)
• Moon’s pull is supplemented or offset by sun’s
gravity.
Neap Tide

• Smaller high and low

tides
• Moon is in the 1st and
3rd quarter (forms
900with the sun)
• Moon’s pull is
stronger but the sun’s
gravity lessens it.
 Wind system and pressure belts
(general circulation of the atmosphere)
5. The kind of climate that prevail over a large
region of the earth’s surface.

a. Macroclimate
b. Mesoclimate
c. Microclimate
d. a or b
e. None of the above

Answer: a. Macroclimate
Kinds of climate:

1. Macroclimate – climate that prevail over a large region

of the earth’s surface

2. Mesoclimate – areas up to several square miles (e.g.

river valleys, mountain areas, basins &
watersheds, shores, urban areas)

3. Microclimate – over short distances, or within few feet or

inches (e.g. streets, immediate plant
surroundings, garden plot)
6. The level/zone of the atmosphere which
contains 4/5 of its mass and where most
clouds form

a. Stratosphere
b. Troposphere
c. Mesosphere
d. Thermosphere
e. Exosphere

Answer: b. Troposhere
Structure of the Atmosphere
Exosphere

Thermosphere/Ionosphere

Mesosphere (UV Rays, cosmic rays, meteors)

(Ozone Maximum)
Stratosphere

(most clouds, 4/5 of mass))

Troposphere

Temperature
7. When the incoming radiation from the sun
strikes an obstruction in the atmosphere, it
becomes
a. Short wave radiation
b. Long wave radiation
c. Greenhouse gas
d. Rainbow
e. Any of the above

Answer: b. Long wave radiation

8. All are causes of atmospheric optical
phenomena, except

a. Refraction
b. Reflection
c. Diffraction
d. Scattering
e. None of the above

Answer: e. None of the above

Rainbows,
Halos

Mirages,
Rainbows,
Halos

Sky Color,
Crepuscular
Rays, Coronas,
Glories

Coronas,
Iridescence
9. Which is not an atmospheric optical
phenomena
a. Lightning
b. Rainbow
c. Corona
d. Aurora
e. None of the above

Answer: e. None of the above

10. Most of the sun’s radiation

a. is absorbed by the atmosphere/clouds

b. is reflected back
c. reach the earth’s surface
d. is lost in space
e. is absorbed by the blackhole

Answer: c. reach the earth’s surface

11. The additional force or acceleration acting on
the motion of bodies in a rotating system of
reference

a. Insolation
b. Albedo
c. Coriolis effect
d. Doppler effect
e. Gravitational effect

Answer: c. Coriolis effect

12. The Philippines is under what type of
climate?

a. Semi-arid mid-latitude
b. Semi-arid low-latitude
c. Humid marine
d. Humid archipelagic
e. Tropical

Answer: e. Tropical
13. These are large scale seasonal winds and are
the seasonal version of diurnal land and sea
breeze.

a. Fronts
b. Monsoon
c. Cyclone
d. Storms
e. Trade wind

Answer: b. Monsoon
14. Winds that blow westward and toward the
equator in both northern and southern
hemisphere.

a. Fronts
b. Monsoon
c. Cyclone
d. Storms
e. Trade wind

Answer: e. Trade winds

15. Fronts that move in such a way that
the warm air advances and the cold
air retreats.
a. Occluded front
b. Cold front
c. Warm front
d. Stationary front
e. None of the above

Answer: c. Warm front

Fronts - are air-mass boundaries that lie along line of
low pressure

Cold Front - the cold air

advances and the warm
air retreats
Warm Front - the warm air
advances and the cold air
retreats
Occluded Front - combination Stationary Front - temporarily
of the warm and cold front, fixed boundary between polar
where cold air overtakes and and tropical air
lifts the warm front masses
16. These are large rotating storms with
diameter ranging 100-1600 km, wind
velocity of 120 kph or higher and
accompanied by heavy rains and high tide.

a. Typhoon
b. Hurricane
c. Cyclone
d. Willy-willy
e. All of the above

Answer: e. All of the above

Terms for Typhoons:
Typhoon – North and South Pacific
Cyclone – Indian Ocean
Hurricane – in North Atlantic and Carribean Sea
Willy-willy – Australia and Oceania
Cyclone/Typhoon/Hurricane - storm in a region of low
surface pressures
Development of Tropical Cyclone:
1. Low Pressure Area
2. Tropical Disturbance
3. Tropical Depression – winds up to 63 kph
4. Tropical Storm – wind velocity of 64-119 kph
5. Tropical cyclone/typhoons – winds velocity 120-240 kph
- are large rotating storms ranging from 100-1,600 km in
diameter and accompanied by violent, destructive winds,
heavy rains, and high tide
6. Supertyphoon – sustained winds of at least 240 kph
17. It is an atmospheric zone near the equator
where the north and south trade winds meet,
varying in position and extent according to
the season.
a. Doldrums
b. ITCZ
c. Fronts
d. a or b
e. b or c

Answer: b. ITCZ
Intertropical Convergence Zone (ITCZ)
Low pressure area around equator where prevailing winds
are calm.
*Convergence of trade winds.
18. Oceanic and atmospheric phenomenon
characterized by unusually warm ocean
current conditions causing climatic
disturbances of varying severity.
a. Fronts
b. Doldrums
c. El Niño
d. Warm ocean breeze
e. Tornadoes

Answer: c. El Niño
19. A requisite for the occurrence of a
tornado
a. Wide flat land
b. Low pressure area
c. Warm front
d. Presence of mountains
e. After a rainfall event

Answer: a. Wide flat land

Tornadoes - are the fastest most violent winds on earth
- top speed of 110 kph near the ground and stay
about 10 minutes (though a few monster
tornadoes from a mile or more wide and can last
for an hour or more)

Requisites:
 warm moist air in the lower atmosphere
 much colder and drier air aloft
 wide land
 something to give the air near the ground an upward shove.
(often this is heated air that wants to rise, because
it's lighter that the surrounding air)
20. An instrument use to measure continuous
record of air temperature.

a. Thermograph
b. Hygrometer
c. Max-min Thermometer
d. Psychrometer
e. None of the above

Answer: a. Thermograph
21. Which parameter is not gathered/
monitored in an agromet station?
a. Atmospheric temperature
b. Soil temperature
c. Wind direction
d. Insect infestation
e. Non of the above

Answer: e. None of the above

Major data collected in a Standard Agromet Station:
- rainfall
- temperature (atmospheric and soil)
- atmospheric pressure
- relative humidity
- wind data
- solar radiation
- evaporation
- phenological observations (crop growth and
production data, animal diseases outbreak,
insect population and infestation, etc.)
Phenology – the study of animal and plant life cycle as
affected by seasonal variations of climate
22. Is the temperature at which the air, if cooled,
will attain saturation.

a. Kindling temperature
b. Dew point temperature
c. Wet bulb temperature
d. Dry bulb temperature
e. Flash point

Answer: b. Dew point temperature

23. An 8-mm rainfall was recorded by a standard
raingauge (8-in. diameter.). Determine the
height of water in the inner cylinder.
a. 0.8 mm
b. 0.8 cm
c. 80.0 mm
d. 80.0 cm
e. 8 cm

Answer: b. 80 mm
 A = 20 cm (8”)
1
area  AREA
10
a

The actual rainfall depth is magnified 10 times in the

collecting cylinder.
24. The diameter of the measuring tube of the
standard 8-in diameter rain gage.
A = 20 cm (8”)
a. 0.8 in
1
b. 1.6 in area  AREA
10
c. 2.53 in  2 1  2 
d h  D H
d. 2.83 in 4 10  4 
e. 3.25 in

Answer: c. 2.53 in
25. For estimating potential evaporation or
evapotranspiration rate, the anemometer
should be located ________ above the ground.

a. 1 m
b. 2 m
c. 5m
d. 10 m
e. None of the above

Answer: b. 2m
26. A rain gage should be located in a flat area
with the orifice approximately _____ above
the ground surface.

a. 1 m
b. 2 m
c. 5m
d. 10 m
e. None of the above

Answer: a. 1m
27. Which of the following chemicals is used in
cloud seeding?

a. Sodium chloride
b. Ammonium nitrate
c. Urea
d. Calcium carbide
e. All of the above

Answer: e. All of the above

The condensation into water droplets and sublimation into ice
crystals of atmospheric water vapor generally occur around
condensation or sublimation nuclei.
Principal types of these nuclei
a. Dusts
b. ocean salt
c. products of combustion and oxides
of nitrogen
d. Other particulate matter
(less than a micron in diameter)
28. Is the primary cause of condensation and,
hence, is responsible for most precipitation. It
results mainly from expansion of air mass
produced from a decrease in atmospheric
pressure.
a. Adiabatic cooling
b. Mixing of air masses
c. Contact cooling
d. Radiation cooling
e. None of the above

Answer: a. Adiabatic cooling

The initial process in the formation of precipitation is the
condensation or sublimation of atmospheric moisture.

Causes of condensation or sublimation

1) adiabatic cooling
2) mixing of air masses of varying temperatures
3) radiation cooling
4) contact cooling
Adiabatic /dynamic cooling

Is the primary cause of condensation and hence, is responsible for

most precipitation.

Adiabatic cooling results mainly from expansion of air mass which

results from a decrease in atmospheric pressure.

Adiabatic cooling is triggered primarily

by the upward or vertical motion of air
masses. As a result, storm or
precipitation events are usually
classified according to the conditions
that cause this upward motion.
The initial process in the formation of precipitation is the
condensation or sublimation of atmospheric moisture.

Causes of condensation or sublimation

1) adiabatic cooling
2) mixing of air masses of varying temperatures
3) radiation cooling
4) contact cooling
29. This type of precipitation results from the
differential heating of air masses near the
ground surface resulting in the upward
movement of warmer air masses.
a. Convective precipitation
b. Orographic precipitation
c. Cyclonic precipitation
d. Frontal Precipitation
e. Both c and d

Answer: a. Convective precipitation

TYPES OF PRECIPITATION

1. Convective precipitation

2. Orographic precipitation

3. Cyclonic precipitation
1. Convective Precipitation
This type of precipitation results from the differential heating of air
masses near the ground surface resulting in the upward movement
of warmer air masses.

A heated air mass moving

upward is cooled down by the
surrounding air and by the
expansion process. Cooling
brings about condensation
which may develop into
precipitation.
 May be in the form of light showers to cloudburst or
thunderstorm depending on the temperature and
moisture conditions

 Convective precipitation are usually highly localized

and of short duration.

 Typical of the tropics

2. Orographic precipitation

Precipitation influenced by topography

Moist air masses moving
over mountain barriers are
cooled, resulting in
condensation and
precipitation. Such air
masses get dry and warm
as they move downslope
on the leeward side of the
mountain barriers.
The influence of this type of
precipitation on the climate of
many areas in the Philippines
is very significant considering
that the Philippines is
mountainous and made up of
a chain of many islands

Orographic types of rainfall are usually of very

low intensity.
 3. Cyclonic precipitation

Are associated with the movement of air masses due

to differences in barometric pressure

This type of precipitation is

triggered by the presence of a
low pressure into which air flow
converges resulting in the lifting
and subsequent cooling of air
masses.

In most parts of the Philippines, more than 80% of the total rainfall
are attributable to cyclonic precipitation.
30. A hydrologic data series which considers only
the largest value of a given year

a. Annual series
b. Partial duration series
c. Daily series
d. Monthly series
e. Seasonal series

Answer: a. Annual series

a. Annual Series
- only the largest event for each year is selected for analysis

Application:
When the design is controlled by the most critical condition, such as
the design of spillway, the annual series should be used.
b. Partial Duration Series
All values above a given base are chosen regardless of the number
within a given time period.
Application:
An example is the design of farm drainage in which the damage may
be due to the extent of flooding, which in turn may be caused by
associated peak flows.

* The annual and partial

duration series give
essentially identical results
for recurrence intervals
greater than ten years.
31. A type of weir used when accurate
measurement of low streamflow is required.

a. Broad-crested
b. Sharp-crested
c. Flume
d. Sluice
e. None of the above

Answer: b. Sharp-crested
32. Which of the following weir cross-sections is
appropriate for high streamflow?

a. Triangular
b. V-notch
c. Rectangular
d. Both a and b
e. All of the above

Answer: c. Rectangular
33. An artificial open channel built to contain and
measure streamflow and appropriate for
sediment-laden flows.

a. Weir
b. Flume
c. Spillway
d. Sluice
e. Drop inlet

Answer: b. Flume
34. Based on the Modified Coronas classification,
a dry month is one with rainfall

a. Less than 100 mm

b. Less than 50 mm
c. 50-100 mm after 3 months of < 50 mm
d. Both a and c
e. Both b and c

Answer: e. Both b and c

35. Class A Evaporation Pan is ______ diameter
and ______ deep.

a. 120 cm, 25 cm
b. 120 cm, 30 cm
c. 180 cm, 25 cm
d. 180 cm, 50 cm

Answer: a. 120 cm, 25 cm

 Class A Evaporation Pan measurement is highly correlated
with the potential evapotranspiration of the surrounding area.

Stilling Well

120 cm (47.5”) 25 cm
(10”)

Class A Evaporation Pan

Class A Evaporation Pan installation requirements:

 Galvanized iron Gage 20

 Operating water level depth: 175~200 mm

(water level kept at 50~75 mm from the rim)

 Installed 150-mm from the ground on wooden

stand/platform

 Measuring stick is 1.0 m and accuracy of 0.02 mm.

36. The water level in the evaporation pan must
be _______.

a. 2-4 in
b. 2-5 in
c. 2-6 in
d. 2-7 in
e. 2-8 in

Answer: e. 2-8 in
37. A porous-bottomed tank used to directly
measure actual evapotranspiration from a
block of soil
a. Atmometer – evaporation from wet surface

b. Phytometer - transpiration
c. Lysimeter
d. Flow meter – water velocity
e. Pyranometer – solar irradiance

Answer: c. Lysimeter
38. Is the science that deals with the occurrence,
distribution and disposal of water on the
planet

a. Hydrology
b. Meteorology
c. Hydrometeorology
d. Both a and b
e. All of the above

Answer: a. Hydrology
39. The following are basic data required for the
analysis and design of a hydrologic project,
except

a. Precipitation record
b. Stream flow record
c. Water quality data
d. Cropping pattern
e. None of the above

Answer: None of the above

40. Which is not a component of the Water
Balance Equation?

a. Inflow
b. Outflow
c. Storage
d. Groundwater
e. None of the above

Answer: e. None of the above

41. Is a water–bearing geologic formation or
stratum capable of transmitting water
through its pores at a rate sufficient for
economic extractions by wells.
a. Aquifer
b. Aquitard
c. Aquiclude
d. Aquifuge
e. All of the above

Answer: a. Aquifer
Aquifer - formations having structures that permit
appreciable water to move through them under ordinary
field conditions (e.g. sand)
Aquiclude is an impermeable formation which may
contain water but is incapable of transmitting significant
water quantities (e.g. clay)

Aquifuge is an impermeable formation that neither

contain nor transmit water (e.g. solid granite)
42. Is the volume of water, expressed as a
percentage of the total of the saturated
aquifer that will drain by gravity when the
water table drops due to pumping or drainage
a. Specific capacity
b. Specific yield
c. Specific retention
d. A or b
e. All of the above

Answer: b. Specific yield

The specific retention, Sr, of soil is the ratio
expressed as a percentage of the volume of water it
will retain after saturation against the force of gravity
to its own volume.

The water which can be drained is expressed as the

specific yield, Sy.
43. Lithologic properties such as aquifer
thickness, depth, and particle size
distribution is important in _________,

a. Well design
b. Pump choice
c. Suitability of water
d. Estimating safe yield
e. All of the above

Answer: e. all of the above

44. Which of the following is a cause of
condensation or sublimation of atmospheric
moisture resulting to the formation of
precipitation?
a. Adiabatic cooling
b. Radiation cooling
c. Contact cooling
d. Mixing of air w/ varying temperature
e. All of the above
Answer: e. all of the above
45. The form of precipitation characterized as
falling drops of 0.5 to 6 mm in diameter.

a. Drizzle
b. Rain
c. Dew
d. Fog
e. Mist

Answer: b. Rain
Precipitation is that part of atmospheric
moisture that falls on the earth surface.

It is primary input into the hydrologic cycle.

Forms of Precipitation:
a. Rain
b. Snow
c. Sleet
d. hail
Rain and Shower (rain shower)

Showers come from cumuliform clouds – cumulus and

cumulonimbus.

Showers can be showers of rain, snow or hail but if snow

or hail is expected it is named directly.

“Showers” by itself always means showers of rain.

Showers are bursts of rain e.g. a rain shower of say 5

mins, followed by a dry spell, then another rain shower
of 10 mins. etc.
Rain and Drizzle

Rain comes from stratiform cloud (altostratus and

nimbostratus)

Drizzle comes from stratus cloud which is very low level

cloud, often lifted fog.

Drizzle is defined by its size, the droplets always with a

diameter of less than 0.5mm. Larger than that, they are
raindrops. The maximum size of a raindrop is 5-6mm.
46. Precipitation associated with the movement
of air masses due to the difference in
barometric pressure

a. Convective
b. Orographic
c. Cyclonic
d. Frontal
e. Monsoon

Answer: c. Cyclonic
47. More than 80% of the rainfall in most part of
the Philippines is attributed to

a. ITCZ
b. Doldrums
c. Tropical cyclone
d. Southwest monsoon
e. All of the above

Answer: c. Tropical cyclone

48. Precipitation station X was inoperative for part of a month
during w/c a storm occurred. The respective storm totals at
three surrounding stations, A, B, and C, were 98, 80, and
110 mm. The normal annual precipitation of station X, A, B,
and C are respectively 880, 1008, 842, and 1080 mm.
Estimate the storm precipitation for station X .

a. 2.7
b. 9.4
c. 8.4
d. 3.4
e. 5.7

Answer: d. 3.4
 Estimation of missing precipitation data

Normal-ratio method - seasonal and annual rainfall magnitudes

1  Nx Nx Nx 
Px   PA  PB  Pc 
3 NA NB NC 
where:
Px = estimated precipitation total for station x (with missing records)
NA,NB, NC = the normal precipitation totals for the index stations A, B, C
for the desired time periods
Nx = normal precipitation at station x for the desired time periods
PA, PB, PC = precipitation totals for the desired time period for the three
index stations
In this method, the three nearest stations with long years of
records are chosen as index stations.

Note:
If the normal precipitation in each of these three index stations is
within 10% of that for the station with the missing record, a
simple arithmetic average of the precipitation totals of the index
stations for the time period in question will suffice.
48. Precipitation station X was inoperative for part of a month during w/c
a storm occurred. The respective storm totals at three surrounding
stations, A, B, and C, were 98, 80, and 110 mm. The normal annual
precipitation of station X, A, B, and C are respectively 880, 1008,
842, and 1080 mm. Estimate the storm precipitation for station X.
Rain Gage A has a missing data. The rainfall data of the four surrounding
stations B, C, D, E for that same period are 10.5, 14.0, 13.25, and 16.35
in, respectively. If the normal annual precipitation amounts of the five
stations are A= 183 in, B=176 in, C= 159 in, D=197 in, and E=218 in,
estimate the missing data of Rain Gage A during that period.
Rain Gage Y has a missing monthly data. The monthly rainfall data of its
surrounding stations A, B, C, for the same month are 145, 145, and 163
mm, respectively. If the normal annual precipitation amounts of the station
are A= 1780 mm, B=1637 mm, C= 1952 mm, and Y=1804 mm, estimate
the missing data of Rain Gage Y during that period.
49. The method of determining average areal
precipitation which accounts for the effect of
topography and unequal gage density

a. Arithmetic average
b. Thiessen method
c. Isohyetal method
d. Both a and b
e. Both b and c

Answer: c. Isohyetal method

 Computation of Areal Precipitation

1. Arithmetic Averages
The simplest of the area averaging methods, this involves averaging arithmetically
all the rain amounts measured by the raingages within the area. This method,
however, assumes uniform gage coverage of the area and linear variations in
rainfall in between any two gaging stations.
2. Thiessen method

The method assumes

that the rainfall in an
area may be taken as
similar to that recorded
in the nearest gaging
station.
 3. Isohyetal method

In this method, the rainfall

depths recorded in all the
stations in and around an area
of interest are plotted on a
map of desirable scale. By
interpolation, lines of equal
rainfall depths or isohyets,
considerations may be given to
various factors influencing the
precipitation over an area
(e.g., orographic effects).
 Advantages Disadvantages
A. ARITHMETIC AVERAGE
1. Fast and easy 1. Ignores orographic effects
2. Objective 2. Uses only stations within the
basin
3. Accurate to extent controlled 3. Gives poor results if stations
by gage density are unequally distributed
4. Subject to only slight error in (which is the general case)
computation
 Advantages Disadvantages
B. THIESSEN METHOD
1. Stations are weighted 1. Requires some skills at drawing
according to area Thiessens
controlled
2. Utilizes stations outside 2. Slow
basin
3. Objective 3. Orography generally ignored
4. Stations have fixed areas of control
5. Requires more computations.
Therefore, subject to more errors.
 Advantages Disadvantages
C. ISOHYETAL METHOD
1. Possible to account for topography 1. Subjective
2. Gives best results (most accurate) 2. Slow
3. Takes advantage of unequal gage 3. Requires some training and skill
density
4. Utilizes stations outside basin 4. Subject to possible large errors due
5. For large basins it is possible to to number of computations
determine contributing area. Very
important in streamflow analysis
6. Results can be utilized in
transportation techniques
7. Easy at a glance to see rainfall
pattern
50. The log-normal distribution is a special case of
____ distribution in which skewness of the
transformed data is presumed zero.

a. Normal
b. Probability
c. Pearson Type III
d. Chi-square
e. None of the above

Answer: c. Pearson Type III

Frequency distributions or probability density curves:

Normal
Log-normal
Gamma
Poisson
Pearson types
 NORMAL DISTRIBUTION

A distribution where its cumulative forms can be expressed as straight

lines by the use of the special abscissa scale which is derived from
the characteristics of the normal distribution.

Many phenomena in nature follow this distribution and

hydrologic events are not exceptions.

The variability of the distributions is indicated by the slope of the

cumulative distribution; that is, the greater the variability, the
greater the slope.
Positive or negatively skewed distributions
Positive or negatively skewed distributions
 LOG-NORMAL DISTRIBUTION

The utility of the log-normal

distribution arises from the
fact that many classes of data
form a skewed distribution
close to normal results. This
distribution has found a place
in many different fields of
science.
PEARSON TYPE III DISTRIBUTION
- considers the skewness of the logarithmically transformed
hydrologic data

Compared to the log-normal distribution, it has a wider

range of application.

The log-normal is just a special case of the Pearson Type III

distribution; that is when the skewness of the transformed
data is zero.
51. The study and determination of evapotranspiration
is important in

a. Moisture conservation and control

b. Estimation of irrigation equipment
c. Determination of water available in storage reservoir
d. All of the above

Answer: d. All of the above

52. The rate of evapotranspiration occurring
under field conditions for the given crop, soil
moisture, and meteorological conditions.

a. Potential Evapotranspiration
b. Reference Evapotranspiration
c. Reference Crop Evapotranspiration
d. Actual Crop Evapotranspiration
e. All of the above

Answer: d. Actual Crop Evapotranspiration

Types of Evapotranspiration
 Combined Mass Transport and Energy Balance

Penman (1948) mainly for estimating evaporation for an open water

surface. On the basis of this equation, other workers such as Van Bavel
(1966) developed an equation for estimating potential evapotranspiration.

Penman equation is so far the most theoretically sound equation for

estimating potential evapotranspiration (PET).

It is sometimes referred to as the combination equation because it combines

the effects of heat transfer and air mass movement in transporting water
molecules from evaporating or transpiring surfaces into the atmosphere.
In compatible but mixed system of units, Penman Equation may be
expressed as:

H  0.27 E a
Et 
  0.27

Et = potential evapotranspiration in mm of water per day

H = heat budget at the evapotranspiring surface in mm of
water per day
Δ = slope of the saturated vapor pressure curve of air at
absolute temperature in oF in mm-Hg/oF.
Ea = evaporation (due to mass movement) in mm of
water per day
Penman Equation
Reference Evapotranspiration (ETo)

is the loss of water to the atmosphere by evaporation and transpiration from a

reference crop, usually a well-watered and mown lawn 100mm in height. By
applying a suitable coefficient, this value can be used to estimate the crop
evapotranspiration (ETc) and the evaporation losses from storage and reticulation
systems.

The ET rate is normally expressed in millimetres (mm) per unit time (mm/day)
– it represents the amount of water evaporated from a cropped surface
in units of water depth.
The evaporation power of the atmosphere is expressed by
the reference crop evapotranspiration (ETo), which
represents the ET from a standardised vegetated surface
(well-watered grass).

Calculation of ETo is generally performed by automatic

weather stations, software packages or ET data providers
The current standard for calculating ETo is the Penman-Monteith method –
also referred to as the FAO 56 method. Calculations based on pan
evaporation are no longer used as the standard.
Hargreaves Radiation Equation
Pan Evaporation Equation
Crop Evapotranspiration (ETc)

describes the actual ET of a crop given standard conditions of

optimum soil water, excellent management conditions, large fields
and full production. Understanding and determining crop (ETc) is
critical for scheduling irrigations to meet the crops water use
demands and to optimise crop production.
53. An equation or method used in the
estimation and representation of
evapotranspiration rate

a. Hargreaves equation
b. Horton’s equation
c. Lewis-Kostiakov equation
d. Rational equation
e. Gardner and Windsoe equation

Answer: a. Hargreaves equation

54. The passage of water into the soil surface

a. Infiltration
b. Seepage
c. Percolation
d. Leaching
e. All of the above

Answer: a. Infiltration
55. Part of runoff which travels over the ground
surface and through the channels to reach the
basin outlet
a. Surface runoff
b. Overland flow
c. Direct runoff
d. Both a and b
e. All of the above

Answer: e. All of the above

56. The time it takes for the runoff from the
remotest point of the watershed to reach the
outlet

a. Time to peak
b. Runoff time
c. Recession time
d. Time of concentration
e. Base time

Answer: d. Time of concentration

Time of Concentration

tc = 0.0195L0.77S-0.385
where: L – maximum length of slope
S (watershed gradient) = (ΔElevation)/L
57. The time for the surface flow and interflow to
recede and is also known as the duration of
flooding.

a. Time to peak
b. Runoff time
c. Recession time
d. Time of concentration
e. Base time

Answer: c. Recession time

Important Properties of Runoff
Runoff hydrograph – a plot of runoff magnitude versus time.
Hydrograph properties and their relevance to water resources
engineering.
peak flow (qp) – magnitude of floods, design of structures such as
drainage canals, flood spillways and culverts

time to peak (tp) – flood warning time, watershed response, water

quality

runoff volume (V) – total water yield from a storm for a given
watershed

recession time – time for surface and interflow to recede, duration

of flooding

base flow → low flow, dependable flow, groundwater recharge

base time, tb : tb = tp + tr
58. A stream that flows only in direct response
to precipitation.

a. Perennial stream
b. Intermittent stream
c. Ephemeral stream
d. Both b and c
e. None of the above

Answer: c. Ephemeral stream

 Perennial Flow

Intermittent Flow Ephemeral Flow

59. A hydrograph with a unit volume of direct
runoff for a given storm duration.

a. Unit hydrograph
b. Basic hydrograph
c. Triangular hydrograph
d. Synthetic hydrograph
e. All of the above

Answer: a. Unit hydrograph

Basic Flood Hydrograph
60. It is an approximation of the basic hydrograph
and was developed to simplify flood routing
procedures.

a. Unit hydrograph
b. Basic hydrograph
c. Triangular hydrograph
d. Synthetic hydrograph
e. All of the above

Answer: c. Triangular hydrograph

61. The physical characteristic of water which greatly
affect the survival of flora and fauna in the body of
water and its increase will also cause increase in the
biological activity and higher demand for dissolved
oxygen.

a. Sediment
b. Temperature
c. Turbidity
d. Specific conductance
e. pH
Answer: b. temperature
62. It is an index of the oxygen-demanding
properties of biodegradable material in the
water and is the basic indicator of water
pollution.
a. Fecal coliform
b. Turbidity
c. COD
d. BOD
e. Dissolved Oxygen

Answer: d. BOD
63. It is the common measure of the dissolved
chemical constituents in stream flow and is an
index of inorganic pollution.
a. COD
b. BOD
c. TDS
d. TDSS
e. Fecal coliform

Answer: a. COD
64. A 6 m deep, 4" well tapping a water table aquifer was
observed to have a steady water level of 20 m above an
impervious stratum and radius of influence of 500 m. If
the aquifer has a hydraulic conductivity of 18 m/day and
the initial head is 25 m above the stratum. What is the
steady state discharge?
a. 0.02 m3/s
b. 0.16 m3/s
c. 15,205 m3/hr
d. 57,019 m3/hr
e. None of the above

Answer: a. 0.02 m3/s

1. Unconfined aquifer 2. Confined aquifer
- water table serves as the upper surface -where ground water is confined under
of the zone of saturation. pressure greater than atmospheric by
(also known as free, phreatic or non- overlaying, relatively impermeable
artesian aquifer.) strata
(also known as artesian or pressure
aquifer)

3. Perched aquifer
- occurs wherever a ground water body is
separated from the main ground water by a
relatively impermeable stratum of small
areal extent and by the zone of aeration
above the main body of ground water.
Piezometric surface or level of a confined aquifer is an
imaginary surface coinciding with the hydrostatic pressure level
of the water in the aquifer.

'Hydrostatic pressure' is the pressure exerted by a

fluid due to its weight.
Pumping Cone
(Cone of Depression)
– forms in the aquifer
around a pumping well as
the water level decline

Drawdown
– the decline in water level
Confined Aquifer

h0  hw
Q  2Kb
lnr 0 rw 
 Q r2 Q r2
K ln T ln
2bh2  h1  r1 2 h2  h1  r1
Unconfined Aquifer

h h
2 2
Q  K 0 w

lnr0 rw 
Unconfined Aquifer with Uniform Recharge

h h 
2
0
2 P 2
2K

r0  r 
2

Q w r0
ln
K r
64. A 6 m deep, 4" well tapping a water table aquifer was observed to
have a steady water level of 20 m above an impervious stratum
and radius of influence of 500 m. If the aquifer has a hydraulic
conductivity of 18 m/day and the initial head is 25 m above the
stratum. What is the steady state discharge?
A 70-m thick aquifer is overlain by an impermeable layer of hard clay
material. A 30-cm diameter fully penetrating well drilled in the aquifer
yield a 19 lps constant discharge. If the constant drawdown is 6 m below
the overlaying impermeable layer and the aquifer permeability is 5
m/day, how wide is the cone of depression created due to pumping?
A non-artesian well is drilled in an aquifer with a fairly horizontal water
table. The well (φ = 25 cm) has a discharge of 167 m3/hr, creating a 250 m
wide cone of depression. If the height/depth of the water table is 60 m and
the aquifer permeability is 8 m/day, determine the drawdow
65. In discharge measurement, the readings in a
staff gage are useless without this

a. Synthetic hydrograph
b. Rating curve
c. Unit hydrograph
d. Matching curve
e. Flowmeter

Answer: b. Rating curve

66. Determine the average monthly rainfall in a 500 ha
watershed based on the rainfall data for September of 5
rainfall gaging stations. The areas of the corresponding
Thiessen polygons are shown below.
Station Rainfall Total (September), mm Thiessen Polygon Area, ha
A 2190 22
B 1731 106
C 2040 75
D 1560 203
E 1974 94

a. 1747 mm
b. 1774 mm
c. 17470 mm
d. 17740 mm
e. None of the above
Answer: b. 1774 mm
67. Run-off is produced when this property of
the soil surface is exceeded

a. Percolation rate
b. Infiltration rate
c. Seepage
d. Permeability
e. Erodibility

Answer: b. Infiltration rate

68. A flood flow of 5.60 m3/s was determined to
have a 50% probability of occurrence. What is
its return period?

a. 2 years
b. 5 years
c. 20 years
d. 50 years
e. 25 years

Answer: a. 2 years
Recurrence interval, T,
- is defined as the average interval of time within which the magnitude of a given
variable is equaled or exceeded.

Probability of occurrence, P,
- which is defined as the percentage of observed events that are equal to or
greater than a given event within a period of time.

Recurrence interval and probability of occurrence are

inversely proportional

Recurrence interval of an event with a probability of

occurrence of 0.05 would be 1/0.05 or 20 years.
69. An artesian well originates from

a. Unconfned aquifer
b. Perched aquifer
c. Confined aquifer
d. Both a & b
e. Both c & d

Answer: c. Confined aquifer

1. Unconfined aquifer 2. Confined aquifer
- water table serves as the upper surface -where ground water is confined under
of the zone of saturation. pressure greater than atmospheric by
(also known as free, phreatic or non- overlaying, relatively impermeable
artesian aquifer.) strata
(also known as artesian or pressure
aquifer)

3. Perched aquifer
- occurs wherever a ground water body is
separated from the main ground water by a
relatively impermeable stratum of small
areal extent and by the zone of aeration
above the main body of ground water.
70. Geologic formations arranged in increasing
economic attractiveness of pumping

a. Aquifer, aquifuge, aquitard, aquiclude

b. Aquifer, aquiclude, aquitard, aquifuge
c. Aquiclude, aquifuge, aquitard, aquifer
d. Aquiclude, aquitard, aquifuge, aquifer
e. Aquitard, aquiclude, aquifuge, aquifer

Answer: c. Aquiclude, aquifuge, aquitard, aquifer

Aquifer - formations having structures that permit
appreciable water to move through them under ordinary
field conditions (e.g. sand)
Aquiclude is an impermeable formation which may
contain water but is incapable of transmitting significant
water quantities (e.g. clay)

Aquifuge is an impermeable formation that neither

contain nor transmit water (e.g. solid granite)
71. The infiltration equation based on the
exhaustion process

a. Lewis-Kostiakov’s
b. Horton’s
c. Philip’s
d. Darcy’s
e. Hargreaves’

Answer: b. Horton’s
 INFILTRATION EQUATION

An infiltration equation may be expressed as:

a. Instantaneous infiltration rate (f)

b. Cumulative infiltration rate (i)

1. Gardner and Windsoe Equation

i = C1t + C2 (1-eβt)

Where: i = cumulative infiltration at time t

C1, C2 and β = constants or parameters
2. Lewis-Kostiakov

i = ctα
f = αctα-1
Where: c and α are constants with the value
of α in between zero and unity
Lewis-Kostiakov equation implies that at t → ∞, f = 0. This
is only possible if the soil is underlain by an impermeable
layer. As such, the equation will only apply for soil
underlain with impervious layers or for small t values in
soils with pervious layers.

log i = log c + α log t

Hence, it will be very easy to test for the fit of infiltration test
data into this equation.
3. Horton Equation
Horton realized that infiltration rate is a decay type function
whereby continuous infiltration and wetting of the soil will
decrease infiltration due to decrease in soil profile storage
potential, inwashing of fine soil particles into soil voids and
swelling of soil colloids and closing of soil cracks.
All these processes have the nature of an exhaustion
phenomenon.

 fo  fc 
i  fc t    1 
 e  kt

 k 
f = fc + (fo - fc)e-kt
4. Philip
Philip analyzed infiltration as a general phenomenon of water
movement in a porous medium. In particular, he described
vertical infiltration in terms of the partial differential equation,
The resulting equation is a rapidly converging series which
can be truncated after the first two terms without much loss in
accuracy. Thus,

i = St1/2 + At
S 1 / 2
f  t A
2
72. When the groundwater level is higher than the level
of water in the streams/river such that the
groundwater sustains the streamflow even during
dry season, the stream is said to be an

a. Effluent Stream
b. Influent Stream
c. Unsteady Stream
d. Uniform Stream
e. Ephemeral Stream

Answer: a. Effluent Stream

73. In a certain farming area, the probability that it will rain on
a November day is 0.60, the probability that a rainy
November day will be followed by another rainy day is
0.80, and the probability that a sunny November day will
be followed by a rainy day is 0.30. What is the probability
that it will rain, rain, not rain, and rain in this place on four
consecutive November days?
a. 0.0288
b. 0.0864
c. 0.0576
d. 0.0162
e. 0.0413

Answer: a. 0.0288
•Probability that it will be dry if the preceding day was dry

Markov Chain Analysis

73. In a certain farming area, the probability that it will rain on a
November day is 0.60, the probability that a rainy November day
will be followed by another rainy day is 0.80, and the probability
that a sunny November day will be followed by a rainy day is 0.30.
What is the probability that it will rain, rain, not rain, and rain in
this place on four consecutive November days?
Given the following probabilities for a certain dekad:
P(D) = 0.70 P(D/D) = 0.72 P(W/W) = 0.36

a. What is the probability of two consecutive wet days followed by two

consecutive dry days?
b. If a given day is dry, what is the succeeding two days most likely
to be?
74. Static water level is the level at which the water rests
in a well before pumping. On the other hand, pumping
water level is the level at which water stands in a well
when pumping at any given rate. What do you call the
difference between the two water levels?
a. Depression
b. Specific yield
c. Drawdown
d. Area of influence
e. Coefficient storage

Answer: c. Drawdown
Pumping Cone
(Cone of Depression)
– forms in the aquifer
around a pumping well as
the water level decline

Drawdown
– the decline in water level
75. Which is not an advantage in using isohyetal
method in determining average rainfall over
an area?
a. It utilizes stations outside the basin.
b. It is easy at a glance to see rainfall pattern.
c. Its results can be utilized in transportation techniques.
d. It is subject to only slight errors in computation
e. It is possible to account for topography

Answer: d. It is subject to only slight errors in computation

76. Approximately _______ of the water extracted
by plant roots is transpired.

a. 75-79%
b. 80-84%
c. 85-89%
d. 90-94%
e. 95-99%

Answer: e. 95-99%
77. The peak runoff in a 10 ha-watershed
corresponding to a rainfall intensity of 50
mm/hr and a runoff coefficient of 0.8 is

a. 1.1 m3/s
b. 1.6 m3/s
c. 2.1 m3/s
d. 3.1 m3/s
e. None of the above

Answer: a. 1.1 m3/s

Peak Runoff by Rational Equation

Qp = CIA
where; Qp - peak runoff (m3/s)
C – runoff coefficient depending on land use and soil
characteristics
I – mean rainfall intensity
A – watershed area
77. The peak runoff in a 10 ha-watershed
corresponding to a rainfall intensity of 50 mm/hr
and a runoff coefficient of 0.8 is
78. A graph showing level, velocity, or discharge
of water in a channel or conduit plotted
against the time.
a. Hydrograph
b. Stream gauge
c. Staff gage
d. Recharge
e. Stream flow

Answer: a. Hydrograph
79. Lewis-Kostiakov equation for infiltration
implies that at t → ∞, f = 0. This is only
possible if
a. Soil type is clay
b. Soil is underlain by an impermeable layer
c. Soil is covered by a hard pan
d. Water is too viscuous
e. None of the above

Answer: b. Soil is underlain by an impermeable layer

80. Given the following cumulative infiltration
rate equations, determine the instantaneous
infiltration rate equation

i  1.25t 1/ 2
 5.8t
 92.5 
i  0.95t    1 e  kt

 k 
i  1.25t 1/ 2
 5.8t
  92.5 
i  0.95t    1 e  kt

 k 
81. A 27 mm/day water requirement is
equivalent to
a. 1.12 lps/ha
b. 17.88 gpm/ha
c. 3.12 lps/ha
d. 29.75 gpm/ha
e. 2.25 lps/ha

Answer: c. 3.12 lps/ha

82. Which is not an importance in determining
evapotranspiration?
a. To determine irrigation equipment
b. To estimate runoff from watersheds
c. To determine water stored in reservoir
d. To predict rainfall amount
e. All of the above

Answer: c. To predict rainfall amount

83. Evaporation occurs when

a. Atmospheric pressure equals vapor pressure

b. Atmospheric pressure is less than vapor pressure
c. Atmospheric pressure is greater than vapor pressure
d. Atmospheric pressure is equal to osmotic pressure
e. Osmotic pressure is equal to turgor pressure

Answer: b. Atmospheric pressure is less than vapor pressure

84. Type of evapotranspiration that occurs in
saturated surfaces.

a. Potential evapotranspiration
b. Reference evapotranspiration
c. Reference crop evapotranspiration
d. Actual evapotranspiration
e. None of the above

Answer: a. Potential evapotranspiration

85. The most theoretically sound equation for
estimating Potential Evapotranspiration

a. Penman equation
b. FAO-Penman Monteith equation
c. Hargreaves equation
d. Pan evapotation equation
e. None of the above

Answer: a. Penman equation

86. Which of the following describes LAI?

a. Increases as plants mature

b. Decreases as plants mature
c. Maximum during the peak vegetative period of plants
d. Minimum during the peak vegetative period of plants
e. None of the above

Answer: c. Maximum during the peak vegetative period of plants

Leaf area index (LAI)
is a dimensionless quantity that characterizes plant canopies. It is
defined as the one-sided green leaf area per unit ground surface
area (LAI = leaf area / ground area, m2 / m2) in broadleaf canopies.
The separation of ET into evaporation and transpiration over the
growing period for an annual field crop
87. Method of calculating average areal
precipitation involving the construction of
lines of equal precipitation is called

a. Arithmetic method
b. Thiessen method
c. Isohyetal method
d. Kriging method
e. Pearson type III

Answer: c. Isohyetal method

88. In frequency analysis, most hydrologic processes, more
or less, follow this process. This process is governed by
chance and time -dependent. What type of process is
this?

a. Deterministic process
b. Stochastic Process
c. Probabilistic process
d. Hydrolistic Process
e. Partial Duration Process

Answer: b. Stochastic Process

 Hydrologic process

-is any hydrologic phenomenon which undergoes

continuous changes with time
It is either deterministic, probabilistic, or
stochastic in nature.
A deterministic process is one in which a definite law of
certainty exists. It is one where the chance element is ignored as
in the case of flood routing.

A probabilistic or stochastic process is one governed by chance

phenomena, that is, there are so many causes at work that the
influence of one cannot be readily identified.

A stochastic process is time dependent.

This means that the sequence of occurrence of events

or the time series is considered in its analysis.

A probabilistic process, on the other hand, is time series independent.

All hydrologic processes are more or less stochastic.

They are assumed to be either deterministic or

probabilistic to simplify their analysis.

Probabilistic analysis of hydrologic processes deals with the

estimation of the chance or likelihood of occurrence of a given
event by determining the frequency curves of best fit to samples
of hydrologic data.
89. A given stage or depth of flow is converted into
discharge reading using a stage/depth-discharge
relationship curve, otherwise known as

a. Rating curve
b. Flow duration curve
c. Frequency curve
d. Histogram
e. Energy curve

Answer: a. Rating curve

90. The rate at which groundwater moves across
the underground soil profile

a. Transmissivity
b. Conductivity
c. Resistivity
d. Hydraulic conductivity
e. Water yield

Answer: d. Hydraulic conductivity

91. Storm surge signal bears a color ________
when the height of water exceeds 3 m above
the mean sea level

a. Green
b. Yellow
c. Orange
d. Red
e. Black

Answer: d. Red
92. Storm warning signal number when the wind
speed is 171-220 kph, lead time of 12 hours and
with impact of heavy to very heavy damage

a. No. 1
b. No. 2
c. No. 3
d. No. 4
e. No. 5

Answer: d. No. 4
93. Supertyphoon is
equivalent to Storm
Signal Warning ___
a. No. 1
b. No. 2
c. No. 3
d. No. 4
e. No. 5

Answer: e. No. 5
94. Rainfall advisory with Orange-colored
warning means/indicates

a. 15-30 mm rainfall
b. Intense rainfall
c. Alert for possible evacuation
d. Both a and c
e. All of the above

Answer: e. All of the above

95. Under automatic suspension guidelines of
DepEd and CHED, Storm Signal Warning No.
2 indicates

a. No classes in Kindergarten
b. No classes up to Elementary
c. No classes up to High School
d. No classes up to college
e. No classes up to graduate school

Answer: c. No classes up to high school

96. Which among the instruments measures
solar radiation?

a. Pyranometer
b. Ceilometer
c. Hygrometer
d. Evaporation pan
e. Psychrometer

Answer: a. Pyranometer
97. Standard area dimension of an
Agrometeorological Station

a. 5m x 10m
b. 6m x 9m
c. 10m x 15m
d. 12m x 18m
e. 10m x 20m

Answer: b. 6m x 9m
98. Which is not a criteria for the selection of an
Agromet site?

a. Should be level and flood free

b. Accessible for monitoring and maintenance
c. Free from nearby obstruction and shading
d. Facing east direction
e. Has grass cover and no tall weeds

Answer: c. Facing east direction

Criteria for selection of Agromet Station site:

 Accessibility for data monitoring, operation

and maintenance
 Should be in a location truly representative
of the natural conditions of the agricultural
region it suppose to serve

 Site has no problem on right of way,

ownership and security

 Site is fairly level and flood-free

Criteria for selection of Agromet Station site:

 Site free from obstruction

 at least 4x the height of the nearest obstruction
(other reference: 8-10 times)
 no shadow casted greater part of the day

 Facing north
(east-west direction
should be identified)
Criteria for selection of Agromet Station site:

 Site has grass cover and no tall weeds

 Site is not concrete, asphalted, nor made
of crushed stone.
 Security should be provided (fence)
Agromet Station Instruments:
99. Why are rainfall measurement expressed in
terms of depth (mm or in) and not in volume?

a. For consistency
b. For simplicity
c. For uniformity
d. For standardization
e. All of the above

Answer: e. All of the above

Why are rainfall measurements expressed
in terms of depth and not by volume?

b. To provide an international standard and uniform

measurement of rainfall. It is more simple,
effective and easier to measure, describe and
compare amount of rainfall in ‘depth’.

 For consistency, simplicity and standardization

100. A standard anemometer has

a. 2 cups
b. 3 cups
c. 4 cups
d. 5 cups
e. 3-5 cups

Answer: b. 3 cups
Agromet Station Instruments:

Wind-measuring instruments:

a. Anemometer
b. Wind Vane
Anemometer installation
requirements:

 3-cup

 Site where wind flow freely and

not distracted by obstructions (trees, tall buildings, other
structures)

 Oriented in the prevailing wind direction

 Mast should be absolutely vertical.

2 m – flat urban terrain
4~10 m – for rural terrain
for roof installation: 3 m from the most exposed part
Minimum height of an anemometer above ground when there
are obstacles of height h (where h is 12 or more) at various
distances around it is given by the following:

Distance of Obstruction Minimum height of

Anemometer

h 2.0h
5h 1.67h
10h 1.5h
20h 1.25h
25h 1.13h
30h h
Wind vane installation requirements:

 Best mounted in an open terrain, at least 30 m from the

nearest obstruction
(wind can blow freely, no nearby obstruction)

 Should be mounted towards true north

(use magnetic compass and corrected by the magnetic
delineation for specific area)

 Satisfactorily exposed and can rotate 3600

 Mounted 6-10 m above the ground

 Wind vane installation requirements:

 Could be as simple as
handcrafted wooden or light
metal; or as elaborate with
decorative ornament

 Lightning rod may be installed to

minimize risk of damage during
thunderstorm.
AWS (Automatic Weather Station)

 A typical AWS comprises 8

sensors for measuring wind
speed, wind direction, air
temperature, RH, solar
radiation, soil temp., surface
wetness, and rainfall.

 Battery- or solar-powered.
What are the differences between a typical
Agromet station and AWS?

 AWS is an automated version of the traditional Agromet

station, either to save human labor or to enable
measurements from remote areas.

 An AWS is equipped with data storage system, thus

data downloading can be done on a daily, weekly, or
monthly basis. The frequency of data collection can
also be programmed according to the needs and use of
such information.
  Moreover, a telemetry system could be connected to
the AWS so that data can be remotely accessed through
mobile SMS or other form of messages in real time.
Thus, data from the AWS can be transmitted in real
time to a central server which can be viewed from
a web-based system through the Internet.

 While, the data from the existing agromet station are

recorded daily in a prescribed form from PAGASA by an
assigned agromet observer and are submitted to BSWM
every month through mail.