PART 2 Flashcards
Area which contributes runoff or drains water into the reservoir (PAES 609:2016).
Watershed
A thermometer that has a constriction above the bulb that permits the mercury to rise in the
capillary tube but does not allow it to descend the capillary tube unless the thermometer is
reset (PAGASA, 2022).
Maximum thermometer
The science that encompasses the occurrence, distribution, movement and properties of the
waters of the earth and their relationship with the environment (USGS, 2022).
Hydrology
The study of the biological, chemical, and physical features of lakes and other bodies of fresh
water (Oxford Languages, 2022)
Limnology
A branch of meteorology and hydrology that studies the transfer of water and energy between
the land surface and the lower atmosphere (Wikipedia, 2022).
Hydrometeorology
Heavy rainfall or rain that accumulates at a rate of 3 tenths of an inch (0.3 inch or about 7.5
mm), or more, per hour (US National Weather Service, 2022)
Torrential rain
Dominant form of precipitation in the Philippines.
RAINFALL
Kind of thermometer with pin inside its tube which does not go with the expanding liquid when
temperature increases.
Minimum thermometer
Method of areal rainfall determination done by computing the weighted average.
Arithmetic method
An instrument to measure depth of rainfall.
Rain gage
Part of rainfall which runs off the soil as surface or subsurface flow.
Runoff
Ratio of runoff over rainfall.
Runoff coefficient
The part of rainfall that is stored in the root zone and can be used by the plants (FAO, 2022).
This excludes rainfall that does not reach the soil and percolation below the root zone. For
grassed soil surface, it is estimated that this rainfall is greater than 0.5 mm/day.
Effective rainfall
The inverse of the probability of exceedance of a certain hydrologic event.
Return period
Airmass lifting process which is mountain-facilitated.
Orographic
Airmass lifting process facilitated by sunlight or heating.
Convective
Indicates to what depth liquid precipitation would cover a horizontal surface in an
observation period if nothing could drain, evaporate or percolate from this surface
(Graf-Water, 2022).
Precipitation depth
The precipitation depth that corresponds to a liquid quantity of 1 liter falling into a 1 square
meter of ground area.
1 mm
Probability of occurrence in any year of hydrologic event recurring once in 4 years.
P=(1/Return Period)x100
25%
What is the probability of occurrence in any year of a hydrologic event recurring every year?
100%`
Rainfall depths recorded were as follows: 8mm and 2mm for 8:00 A.M. and 2:00 P.M.,
respectively on 7-7-2022 and 5 mm and 9 mm for 8:00 A.M. and 2:00 P.M., respectively on
7-8-2022. What is the total rainfall depth on 7-7-2022?
2 mm
Rainfall on 7-7-2022 = Rainfall at 2:00 P.M. on 7-7-2022 + Rainfall at 8:00 A.M. on 7-8-2022
= 2 mm + 5 mm
= 7 mm
The agrometeorological station uses electronic rain gage. The rainfall depths were recorded on
June 1, 2022 as follows: 2 mm from 6:00 to 8:00 A.M., 7 mm from 8:00 to 10:00 A.M., 9 mm
from 12:00 noon to 2:00 P.M. and zero rainfall for all other times of the day and the previous
day. What is the rainfall intensity recorded on June 1, 2022?
4 mm/hr
Intensity = Depth/Time, time is from 8:00 AM of current day to 8:00 AM of the next day
= (7mm from 8:00 to 10:00 A.M. + 9mm from 12:00 noon to 2:00 P.M.)/(2hr +2 hr)
= 4 mm/hr
Estimate the time of concentration of a certain watershed having a time lag
1.43 hours
TC = TL / 0.70
= 1 hr / 0.70
= 1.43 hrs
The maximum permissible water velocity for clay loam canal surface based on PAES
603:2016.
0.80 m/s
The minimum permissible velocity for water with sediments in lined canals based on PAES
603:2016.
0.9 m/s
Application of water in the soil to supply moisture needed for plant growth.
Irrigation
Loss of water from a channel during transport due to seepage and percolation.
Conveyance loss
Depth of water flow where the energy content is at minimum hence, no other backwater forces are
involved
Critical depth
Ratio of the actual crop evapotranspiration to its potential evapotranspiration.
Crop coefficient
Moisture content of the soil when gravitational water has been removed.
Field capacity
Number of days between irrigation applications.
Irrigation interval
Removal of excess water.
Drainage
Elevated section of open channel used for crossing natural depressions.
Flume
Surveying instrument used for determining land areas in a topographic maps.
Planimeter
Elevation of water surface in a stream with reference to a certain datum
STAGE
Facility for determining water consumptive use of crops in an open field.
Lysimeter
Time required to cover an area with one application of water.
Irrigation period
At optimal emitter spacing, drip emitter spacing is ___ of the wetted diameter estimated from
field tests.
80%
Reference crop evapotranspiration is the rate of evapotranspiration from a reference surface
which is a hypothetical reference crop with an assumed crop height of 0.2 m and an albedo of
_______ (AMTEC, 2020).
0.23
Manufacturer’s coefficient of variation is the measure of the variability of discharge of a random
sample of a given make, model and size of emitter, as provided by the manufacturer and before
any field operations or aging has taken place determined through a discharge test of a sample of
50 emitters under a set pressure at ___ ºC.
A. 200 B. 100 C. 50 D. 30
way asnwer c tambong
Which one is the flattest canal side slope?
4:1
Determine the side slope angle Ө with the horizontal plane of an unlined canal with side
slope ratio (run: rise) z of 2:1.
26.6º
tan Ө = rise /run
Ө = arctan (rise /run)
= arctan (1/2)
= 26.6º
If the most efficient concrete canal has its side angle Ө with the horizontal plane equal to 60º,
what is the z value of the canal sides or the side’s horizontal run in meters per 1 meter rise?
This value is commonly used in designing most efficient concrete canals.
0.577
tan Ө = 1 / z
tan 60º = 1 / z
1.732 = 1 / z
z = 0.577
What is the top width at water surface level of the most efficient concrete open channel if the
design depth is 5 meters? The design discharge is 100 m3
/s and velocity is 2 m/s
12.9 m
What is the total top width of the most efficient concrete open channel if design depth is 5
meters? Design discharge is 100 m3
/s and velocity is 2 m/s. Use 15% freeboard.
13.8 m
What is the base of the most efficient trapezoidal concrete open channel if discharge is 100
m3
/s and velocity is 2 m/s?
6.14 m
What is the bottom width for the best hydraulic cross-section (best proportion) of concrete
open channel if design depth is 5 meters and side slope is 45º?
4 m
What is the bottom width for best hydraulic cross-section of unlined open channel for
minimum seepage if design depth is 5 meters and side slope is 45º?
8.15 m
What is the bottom width for best hydraulic cross-section of unlined open channel with
minimum seepage if design depth is 5 meters and side slope is 2:1?
4.72 m
Estimate the width and depth of concrete-lined rectangular open channel for water velocity of
2 m/s and discharge of 10 m3
/s.
3.2 m, 1.6 m
What should be the base and depth of concrete-lined rectangular open channel for a crosssectional area of 50 m2
? Design for efficiency over proportion.
10 m, 5 m