Irrigation & Drainage Engineering Flashcards
The moisture content of the soil when the gravitational water has been
removed.
a. Available water
b. Field capacity
c. Permanent wilting point
d. Readily available moisture
B – Field capacity
Twelve thousand five hundred (12,500) cubic meters of water was delivered to a 10 ha farm for the month of June in which consumptive use is estimated at 8 mm/day. The effective rainfall for the period was
150 mm. What is the irrigation efficiency?
a. 32%
b. 87%
c. 72%
d. 52%
C – 72%
Evapotranspiration in an 8 ha farm is 7 mm/day and percolation losses is
2 mm/day. What is the design discharge of a canal to be able to deliver a
5-day requirement of the farm in 24 hours if irrigation efficiency is 75%?
a. 150 m3/hr
b. 200 m3/hr
c. 175 m3/hr
d. 140 m3/hr
b. 200 m3/hr
Subsurface drain system wherein laterals join the submain on both
sides alternately.
a. Gridiron
b. Herringbone
c. Parallel drain system
d. Double main system
B – herringbone
How much water should be applied to a 6 ha farm where the rooting
depth is 80 cm, if it is in its permanent wilting point? Volumetric
moisture contents are 0.15 and 0.32 for permanent wilting point and
field capacity, respectively.
a. 7,200 m3
b. 6,120 m3
c. 15,360 m3
d. 8,160 m3
Vol. = (FC – PWP)(D)(A)
= (0.32 - 0.15)(0.8m)(60,000 m2)
= 8,160 m3
What is the depth of water in a trapezoidal channel with a side slope of 2 and carrying a 2.5 m3/s water flow? The channel’s bottom
width is 1.5 meters and the flowing water has a velocity of 0.8 m/s.
a. 1 m
b. 1.2 m
c. 0.93 m
d. 0.82 m
Q = AV or A = Q/V
A = 2.5 m3/s / 0.8 m/s = 3.125 m2
A = by + zy2 : 3.125 = 1.5y + 2y2
solving for y = 0.93 m
How many sprinklers with spacing of 7m x 7m are needed to
irrigate a rectangular piece of land 125 m x 190 m if the laterals
are set parallel to the longer side of the field?
a. 503
b. 504
c. 486
d. 485
C – 486
Number of Laterals, N = 125/7 = 17.86 or 18
Number of Sprinklers/lateral, S = 190/7 = 27.142 or 27
Total number of sprinklers = N x S = 18 x 27 = 486
If the impeller speed of a centrifugal pump is increased from 1800 rpm to 2340 rpm, the resulting power will be how many times the original?
a. 1.690
b. 2.197
c. 1.091
d. 1.140
B - 2.197
P1 (2340/1800)^3 = P2
2.197 P1 = P2
Darcy’s law states that the flow of water through a porous medium is?
a. Proportional to the medium’s hydraulic conductivity
b. Inversely proportional to the length of flow path
c. Both a and b
d. Neither a nor b
C – both a & b
One liter per second is equal to?
a. 16.85 gpm
b. 15.50 gpm
c. 15.85 gpm
d. 17.35 gpm
C – 15.85 gpm
It is the ratio of the volume of voids to the total volume of the
soil.
a. Void volume
b. Bulk density
c. Porosity
d. Void density
C – porosity
A soil sample was obtained using a cylindrical soil sampler with a 4-
inch diameter and 10-inch height. After oven-drying, the sample
weighed 2,470 grams. What is the soil’s bulk density.
a. 12 g/cc
b. 1.1 g/cc
c. 1200 kg/m3
d. 1.3 kg/m3
C – 1200 kg/m3
Vb = Ah = (πd2/4)(h)
= [π(4 in x 2.54 cm/in)2/4] x (10 in x 2.54 cm/in)
= 2,059.3 cm3
BD = ODW/Vb
= 2,470/2,059.3
= 1.2 g/cc = 1200 kg/m3
It is the water retained about individual soil particles by molecular
action and can be removed only by heating.
a. Permanent wilting point
b. Hygroscopic water
c. Hydrophobic water
d. Microscopic water
B – hygroscopic water
A 16-ft thick confined aquifer with hydraulic conductivity of 500 ft/day
was tapped by a 4-inch diameter shallow tube well. With a radius of
influence of 2000 ft, determine the maximum discharge of the STW in
lps. Assume an allowable drawdown of 10 ft.
a. 16.85
b. 17.55
c. 5.59
d. 6.59
B – 17.55
Q = 2πkb(h2 – h1) / ln(r2/r1)
It refers to the composite parts of the irrigation system that divert water from natural bodies of water such as rivers, streams and lakes.
a. Main canal
b. Diversion canal
c. Irrigation structures
d. Headworks
D – headworks
It is a measure of the amount of water that the soil will retain against a
tension of 15 atmospheres.
a. Readily available moisture
b. Permanent wilting point
c. Available moisture
d. Field capacity
B – PWP
What is the discharge in each sprinkler nozzle to irrigate a
rectangular piece of land 150m x 180m if the laterals are set parallel
to the longer side of the field. Sprinkler spacing is 6m x 6m,
irrigation water requirement is 150 mm and irrigation period is 6
hours.
a. 0.250 lps
b. 0.375 lps
c. 0.500 lps
d. 0.125 lps
A – 0.250 lps
Q = 6m x 6m x 0.15m/6hrs x 1hr/3600sec x 1000li/m3
Q = 0.250 lps
The International Soil Science Society describes sand as a soil
particle with a diameter of
a. 0.02 to 2 mm
b. 0.2 to 2 mm
c. 0.002 to 0.02 mm
d. 0.002 to 0.2 mm
B – 0.2 to 2 mm
Ten m3/hr is equal to
a. 2.78 lps
b. 44.03 gpm
c. Both a and b
d. Neither a nor b
C – both a & b
Determine the irrigation interval for a farm with soil root zone having
a field capacity of 200 mm and a wilting point of 105 mm. Assume
that the consumptive use for August is 7.5 mm/day with no rainfall
and the allowable moisture depletion is 75%.
a. 11 days
b. 9 days
c. 4 days
d. 7 days
B – 9 days
int = (FC – WP)(AMD) / CU
= ((200 – 105)mm x 0.75) / 7.5 mm/day
Iint = 9.5 days
What is the depth of water in a trapezoidal channel with a side slope
of 2 and carrying a 3.2 m3/s water flow? The channel’s bottom width is 1.5 meters and the flowing water has a velocity of 0.85 m/s.
a. 1.8 m
b. 1.79 m
c. 1.05 m
d. 1.04 m
C – 1.05 m
Q = AV
A = Q/V = 3.2 m^3/s / 0.85 m/s = 3.765 m^2
A = by + zy^2
3.765 = 1.5y + 2y^2
Compute for y = 1.05 m
The localized lowering of the static or piezometric water level due to
pumping.
a. Groundwater decline
b. Drawdown
c. Subsidence
d. Depression
B – drawdown
Any convenient level surface coincident or parallel with mean
sea level to which elevations of a particular area are referred
a. Datum
b. Elevation
c. Horizontal surface
d. Slope
A – datum
What is the design discharge of a canal to be able to deliver a
7-day requirement of a 5-ha farm in 12 hours if the irrigation
requirement is 8 mm/day?
a. 65 m3/s
b. 6.5 m3/s
c. 0.65 m3/s
d. 0.065 m3/s
D – 0.065 m3/s
Q = (5 ha x 10,000 m2/ha x 8 mm/day x (1m/1000mm) x7 days) / 12 hrs x 1hr/3600sec
Q = 0.0648 m3/s = 0.065 m3/s
It is a geologic formation which transmits water at a rate insufficient to be economically developed for pumping.
a. Aquifer
b. Aquiclude
c. Aquifuge
d. Aquitard
B – aquiclude
Determine the maximum total head at which a 5-hp centrifugal pump
can extract water at a rate of 25 lps if pump efficiency is 65%.
a. 25.32 ft
b. 32.48 ft
c. 33.39 ft
d. 35.12 ft
B – 32.48 ft
BHP = γQH/EP or H = (BHP)(E )/γQ
(γ = 62.4 lbs/ft3)
H = (5 hp x 0.65 x 550 ft-lbs/sec-hp x 1ft/62.4 lbs) / (25 li/sec x 1m3 /1000 li x (3.28)^3 ft3/m3
H = 32.48 ft
It is the ratio of the dry weight of the soil to the weight of the water
with volume equal to the soil bulk volume.
a. Particle density
b. Bulk density
c. Real specific gravity
d. Apparent specific gravity
d. Apparent specific gravity
It accounts for the losses in an irrigation system from the water
source and prior to delivery of water into the field ditches.
a. Evaporation
b. Application efficiency
c. Diversion efficiency
d. Conveyance efficiency
D – Conveyance efficiency
A geologic formation that contains water but do not have the capacity to transmit it.
a. Aquifuge
b. Aquifer
c. Aquitard
d. Aquiclude
D – Aquiclude
Compute the land soaking requirement for a soil (depth of root zone = 60 cm) with residual moisture content of 18% by weight, bulk density of 1,320 kg/m3 and porosity of 50%. Standing water for planting is 20 mm.
a. 177.44 mm
b. 157.44 mm
c. 253.44 mm
d. 273.44 mm
B – 157.44 mm
What is the recommended value for standing water during land
preparation.
a. 5 mm
b. 10 mm
c. 15 mm
d. 8 mm
B – 10 mm
Farm water requirement minus the application losses is the.
a. Diversion water requirement
b. Farm irrigation requirement
c. Application efficiency
d. Land preparation water requirement
B – Farm irrigation requirement
What is the root zone depth of a farm with land soaking requirement
of 90 mm if the soil porosity is 45%, residual moisture content is 18%
(by weight) and bulk density is 1,250 kg/m3?
a. 35 cm
b. 40 cm
c. 45 cm
d. 60 cm
B – 40 cm
This results from overlapping radii of influence of neighboring wells.
a. Drawdown
b. Groundwater decline
c. Well interference
d. Drawdown curve
C – well interference
In furrow irrigation, the rate of water application should be ____ the
intake rate of the soil.
a. Less than
b. Greater than
c. Equal to
d. Not related to
A – less than
Irrigation method is used for row crops wherein only a part of the
surface is wetted
a. Basin flooding
b. Furrow irrigation
c. Border irrigation
d. Border-strip flooding
B – furrow irrigation
Determine the irrigation interval for a farm with soil root zone having a
field capacity of 200 mm and a wilting point of 140 mm. Assume that
the consumptive use is 6 mm/day with no rainfall and the allowable
moisture depletion is 75%
a. 6 days
b. 9 days
c. 7 days
d. 10 days
C – 7 days
Int = (FC-WP)(AMD)/CU
= ((200-140)mm x 0.75)/6 mm/day
= 7.5 or 7 days
What is the design discharge of a canal to be able to deliver a 6-day requirement of a 6-ha farm in 9 hours if the irrigation requirement is 8 mm/day?
a. 88.9 m3/s
b. 8.89 m3/s
c. 0.889 m3/s
d. 0.0889 m3/s
D – 0.0889 m3/s
Q = Ad/t
The amount of drainage water to be removed per unit time per unit
area is the
a. Drainage requirement
b. Drainage coefficient
c. Drain spacing
d. Drainage volume
B – drainage coefficient
In Hooghoudt’s drain spacing formula, it is assumed that
a. The water table is in equilibrium with the rainfall or irrigation water
b. The drains are evenly spaced
c. Darcy’s law is valid for flow through soils
d. All of the above
D – all of the above
A mathematical expression for the macroscopic flow of water through
a porous system
a. Steady state groundwater flow equation
b. Darcy’s Law
c. Laplace’s equation
d. Scobey;s equation
B – Darcy’s Law
It is the soil moisture constant describing the amount of moisture
retained by the soil against a suction pressure of 1/3 atmosphere
a. Field capacity
b. Hygroscopic water
c. Permanent wilting point
d. Saturation point
A – field capacity
Run-off is the difference between the gross depth of irrigation water
and the
a. Net depth requirement
b. Crop evapotranspiration
c. Depth that infiltrated
d. Water use rate
A – net depth requirement
It is the type of sprinkler irrigation system where the number of
laterals installed is equal to the total number of lateral positions
a. Hand move system
b. Periodic move
c. Special type
d. Set system
D – set system
A soil with root zone depth of 1.2 meters has 24% initial volumetric
moisture content, volumetric field capacity and permanent wilting
point of 30% and 15%, respectively and 50% allowable moisture
depletion. The initial depth of water in the soil is
a. 43.2 mm
b. 270 mm
c. 288 mm
d. 360 mm
C – 288 mm
Pv = d/D
Pv = d/DIn previous Problem, when the soil reaches _____, irrigation should
be done
a. 43.2 mm
b. 270 mm
c. 288 mm
d. 360 mm
B – 270
FC = .3 x 1,200 = 360 mm
WP = .15 x 1,200 = 180 mm
AMD = .5(FC-WP) = (0.5)(360-180) = 90 mm }
90 mm
WP + AMD = 180 + 90 = 270 mm
In previous Problem, natural drainage occurs when the soil water reaches or exceeds a depth of _______.
a. 43.2 mm
b. 270 mm
c. 288 mm
d. 360 mm
D – 360 mm
It is a surface irrigation system where the area is subdivided by dikes and water flows over these dikes from one subdivision to another.
a. Border irrigation
b. Furrow irrigation
c. Basin irrigation
d. Corrugation irrigation
C – basin irrigation
Distribution control structures placed across an irrigation ditch to block the flow temporarily and to raise the upstream water level.
a. Turnouts
b. Checks
c. Culverts
d. Weirs
B – checks
Which is not a component of the impact arm of an impact sprinkler?
a. Nozzle
b. Counterweight
c. Vane
d. Spoon
A - nozzle
A 20-ft thick confined aquifer with hydraulic conductivity of 400 ft/day was tapped by a 4-inch diameter shallow tube well. With a radius of
influence of 2,500 ft, determine the maximum discharge of the STW in liters per second. Assume an allowable drawdown of 12 ft?
a. 22.17
b. 20.57
c. 62.71
d. 25.63
B – 20.57
Confined Aquifers
In surface irrigation, the ratio between the gross amount of irrigation
water and the net requirement of the crop is the
a. Application efficiency
b. Deep percolation
c. Seepage
d. Runoff
a – Application efficiency
It is an orderly sequence of planting crop in an area for a 365-day
period
a. Cropping pattern
b. Crop combination
c. Crop sequence
d. Cropping schedule
A – Cropping pattern
A 21.6 mm/day water requirement is equivalent to
a. 23.8 gpm/ha
b. 0.9 lps/ha
c. 2.5 lps/ha
d. 14.3 gpm/ha
C – 2.5 lps/ha
In a 5 ha area, it was determined that the soil volumetric field
capacity and permanent wilting point are 25% and 15%, respectively. Crop consumptive use is 5 mm/day, application
efficiency is 80% and irrigation application rate is 32 m3/hr. The allowable soil moisture depletion is 60%, apparent specific gravity is
1.2 and the depth of root zone is 0.8 m. The net depth of irrigation water to be applied is
a. 80 mm
b. 48 mm
c. 24 mm
d. 36 mm
B – 48 mm
Dnet= (AMD)(FC-WP)(D)
In previous problem, the gross depth of irrigation water to be applied
is
a. 100 mm
b. 60 mm
c. 64 mm
d. 38 mm
B – 60 mm
Dgross= Dnet/Ea
In previous problem, the irrigation interval, in days is
a. 10
b. 5
c. 9
d. 4
C – 9 days
Int = dnet /CU
= (48 mm)/(5 mm/day) = 9.6 or 9 days
In previous problem, the irrigation period, in hours is
a. 93
b. 47
c. 230
d. 94
D - 94
Irrigation Period = ADgross/Q
The head in an emitter discharging 4 liters of water per hour and with
discharge coefficient of 0.798 and exponent of 0.5 is
a. 6.4 m
b. 5.0 m
c. 10 m
d. 1.8 m
25 m
q= (Kd)(Hx)
In furrow irrigation, it is the difference between the depth of water
that infiltrated and the net depth requirement
a. Runoff
b. Application losses
c. Deep percolation
d. Seepage
C – deep percolation
A rectangular piece of land 180m x 240m is laid out with one-sided sprinkler irrigation system. Laterals are set parallel to the longer side of the field. Sprinkler spacing is 6m x 6m, irrigation water requirement is 150 mm and irrigation period is 6 hours. Laterals are set on only one side of the mainline. The sprinkler discharge is
a. 0.50 lps
b. 0.375 lps
c. 0.250 lps
d. 0.125 lps
C – 0.250 lps
In previous problem, determine the number of lateral positions
a. 30
b. 20
c. 40
d. 60
A - 30
No. of lateral positions = 180/6 = 30
In previous problem, determine the number of sprinklers/lateral
a. 30
b. 20
c. 40
d. 60
c - 40
No. of sprinkler/lateral = 240/6 = 40
The field in previous problem is installed with hand-moved system and 2 sets of laterals can be installed per day. Calculate the minimum number of laterals that can be installed per set if there are 5 operating days per irrigation interval
a. 2
b. 4
c. 3
d. 1
C – 3
No. of laterals/set = total no. of laterals/5days
= 30/5 = 6 lat/set
Since there are 2 sets of laterals, then the minimum no. of laterals per set = 6/2 = 3 laterals
In-line canal structure designed to convey canal water from a higher level to a lower level, duly dissipating the excess energy resulting from the drop in elevation
a. Drop
b. Flume
c. Weir
d. None of the above
A – drop
Amount of rainwater that falls directly on the field and is used by the crop for growth and development excluding deep percolation, surface runoff and interception
a. Average rainfall
b. Effective rainfall
c. Rainfall depth
d. None of the above
B – effective rainfall
Applicator used in drip, subsurface, or bubbler irrigation designed to dissipate pressure and to discharge a small uniform flow or trickle of
water at a constant rate that does not vary significantly because of minor differences in pressure
a. Drippers
b. Emitters
c. Nozzle
d. None of the above
B – emitters
Closed conduit designed to convey canal water in full and under
pressure running condition, to convey canal water by gravity under
roadways, railways, drainage channels and local depressions
a. Siphon
b. Inverted siphon
c. Elevated flumes
d. None of the above
B – inverted siphon
Amount of water required in lowland rice production which includes
water losses through evaporation, seepage and percolation and land
soaking
a. Land soaking water requirements
b. Land preparation water requirements
c. Irrigation water requirements
d. None of the above
B – land preparation requirements
Portion of the pipe network between the mainline and the laterals
a. Connector
b. Valve
c. Manifold
d. None of the above
C – manifold
Constant flow depth along a longitudinal section of a channel under a
uniform flow condition
a. Normal depth
b. Critical depth
c. Uniform depth
d. None of the above
A – normal depth
Water flow that is conveyed in such a manner that top surface is
exposed to the atmosphere such as flow in canals, ditches, drainage
channels, culverts, and pipes under partially full flow conditions
a. Open channel flow
b. Canal flow
c. Pipe flow
d. None of the above
A – open channel flow
Tube or shaft vertically set into the ground at a depth that is usually
less than 15 m for the purpose of bringing groundwater into the soil
surface whose pumps are set above the water level
a. Shallow tubewell
b. Deep well
c. Pipe
d. None of the above
A – shallow tubewell
Ratio of the horizontal to vertical dimension of the channel wall
a. Slope
b. Channel gradient
c. Side slope
d. All of the above
C – side slope
Slope of the water surface profile plus the velocity head in open
channels
a. Energy grade line slope
b. Water surface slope
c. Channel bottom slope
d. Hydraulic grade line slope
A – energy grade line slope
Slope of the free water surface in open channel
a. Energy grade line slope
b. Water surface slope
c. Channel bottom slope
d. Hydraulic grade line slope
D – Hydraulic grade line slope
Occurs when flow has a constant water area, depth, discharge, and
average velocity through a reach of channel
a. Normal flow
b. Critical flow
c. Uniform flow
d. Varied flow
C – uniform flow
Accounting of water inflows, such as irrigation and rainfall; and
outflows, such as evaporation, seepage and percolation.
a. Water cycle
b. Water balance
c. Water flow
d. All of the above
B – water balance
Area which contributes runoff or drains water into the reservoir.
a. Watershed
b. River network
c. Streams
d. All of the above
A - watershed
Diameter of the circular area wetted by the sprinkler when operating
at a given pressure and no wind.
a. Wetted diameter
b. Wetted perimeter
c. Diameter of throw
d. All of the above
A – wetted diameter
Portion of the perimeter of the canal that is in contact with the flowing
water.
a. Wetted diameter
b. Wetted perimeter
c. Diameter of throw
d. All of the above
A – wetted perimeter
Moisture left in the soil before the initial irrigation water delivery which
describes the extent of water depletion from the soil when the water
supply has been cut-off.
a. Current soil moisture content
b. Residual moisture content
c. Allowable moisture depletion
d. None of the above
B – residual moisture content
Pressure required to overcome the elevation difference between the
water source and the sprinkler nozzle, to counteract friction losses
and to provide adequate pressure at the nozzle for good water
distribution.
a. Average pressure
b. Design pressure
c. Pressure requirement
d. None of the above
B – design pressure
An overflow structure built perpendicular to an open channel axis to
measure the rate of flow of water.
a. Weir
b. Flume
c. Orifice
d. None of the above
A – weir
In-line structure with a geometrically specified constriction built in an
open channel such that the center line coincides with the center line
of the channel in which the flow is to be measured.
a. Weir
b. Flume
c. Orifice
d. None of the above
B – flume
Measuring device with a well-defined, sharp-edged opening in a wall
through which flow occurs such that the upstream water level is
always well above the top of this opening.
a. Weir
b. Flume
c. Orifice
d. None of the above
C – orifice
A device with individual scales on the rods to provide data to plot
furrow depth as a function of the lateral distance where data can then
be numerically integrated to develop geometric relationships such as
area verses depth, wetted perimeter versus depth and top-width
verses depth.
a. Infiltrometer
b. Profilometer
c. Penetrometer
d. None of the above
B – profilometer
Application of water by gravity flow to the surface of the field.
a. Surface irrigation
b. Furrow irrigation
c. Basin irrigation
d. None of the above
A – surface irrigation
Method of irrigation where water runs through small parallel channels
as it moves down the slope of the field.
a. Surface irrigation
b. Furrow irrigation
c. Basin irrigation
d. None of the above
B – furrow irrigation
Recommended slope for furrow irrigation method.
a. 0.05 % to 3.0 %
b. 2.0% to 5.0%
c. ≤ 0.1%
d. None of the above
a. 0.05 % to 3.0 % - FURROW
b. 2.0% to 5.0% - BORDER
c. ≤ 0.1% - BASIN
d. None of the above
A trapezoidal channel has a base width of 6 meters and a side slope of 1H:1V. The channel bottom slope is 0.0002 and the
Manning roughness coefficient is 0.014. What is the depth of flow if Q = 12.1 m3/s?
a. 1.5 m
b. 1.3 m
c. 1.7 m
d. 1.1 m
A – 1.5 m
A trapezoidal channel has a base width of 6 meters and a side slope
of 1H:1V. The channel bottom slope is 0.0002 and the Manning
roughness coefficient is 0.014. What will be the state of flow if the
depth of flow is 1.5 m?
a. Critical
b. Sub-critical
c. Supercritical
d. Laminar
B – sub-critical
What is the required power if the needed system capacity is 25 m3/hr and the total dynamic head is 40 meters. The pump efficiency is 60%.
a. 3 hp
b. 5 hp
c. 7 hp
d. None of the above
C – 7 hp
Determine the nominal pipe diameter for the 20 m3/hr flow if the allowable velocity in pipe is 2 m/s.
a. 50 mm
b. 63 mm
c. 75 mm
d. None of the above
B – 63 mm
Q = AV
Q = (πD2 /4) V
D = (4Q/ πV)^1/2
Any barrier constructed to store water.
a. Reservoir
b. Dam
c. Tank
d. None of the above
B – dam
Volume of water stored in reservoir between the minimum water level
and normal water level.
a. Active storage
b. Dead storage
c. Storage capacity
d. None of the above
A – active storage
Maximum elevation the water surface which can be attained by the
dam or reservoir without flow in the spillway.
a. Maximum storage elevation
b. Dam crest elevation
c. Normal storage elevation
d. None of the above
C – normal storage elevation
Part of water impounding system that stores the runoff.
a. Watershed
b. Reservoir
c. Dam
d. None of the above
C – dam
A trapezoidal channel carrying 400 cfs is built with nonerodible bed
having a slope of 0.0016 and n = 0.025. Determine the depth of
water, y if b = 20 ft and z = 2
a. 3.36 ft
b. 2.87 ft
c. 5.72 ft
d. 4.13 ft
A – 3.36 ft
On previous problem, determine the cross-sectional area, A of the
channel.
a. 72.36 ft2
b. 89.78 ft2
c. 63.56 ft2
d. 83.92 ft2
B – 89.78
A = 20 + 2 x 3.36 x 3.36 = 89.78ft2B – 89.78
A = 20 + 2 x 3.36 x 3.36 = 89.78ft2
On previous problem, determine the best hydraulic section?
a. y = 3.36 ft; b = 3.74 ft
b. y = 4.52 ft; b = 6.26 ft
c. y = 6.60 ft; b = 7.62 ft
d. y = 7.81 ft; b = 9.76 ft
C – y=6.6 ft; b=7.62 ft
A triangular channel section with a bottom angle 80o with channel
gradient 0.0016 and n = 0.025, carries a discharge of 400 cfs;
What is the normal depth of flow?
a. 3.32 ft
b. 6.76 ft
c. 9.68 ft
d. 10.12 ft
C – 9.68 ft
The estimated width and depth of concrete-lined rectangular open
channel for water velocity of 2 m/s and discharge of 10 m3/s?
a. 6.1 m, 2.3 m
b. 3.2 m, 1.6 m
c. 2.5 m, 5.0 m
d. None of the above
b – 3.2 m, 1.6 m
