AREA 2 Flashcards
IDE, SWCE
PAES: 615
In effective size, particle diameter corresponding to a ___ sieve passing
a. 5%
b. 10%
c. 15%
d.20%
b. 5%
PAES: 615
Another term for BORED WELL
a. Augered well
b. Vadous well
c. Macro well
d. Unconfined well
a. Augered well
- used in formations with very shallow water
depths
The hydraulic radius of a pipe with a diameter of 12mm is
a. 113 mm
b. 6 mm
c. 4 mm
d. 3 mm
d. 3 mm
Solution:
R = d/4 = 12mm/4 = 3mm
If the theoretical flow of velocity in an orifice is 4 m/s, what is the height of water flowing above the center of the orifice?
a. 0.61 m
b. 0.71 m
c. 0.81 m
d. 0.91 m
c. 0.81 m
h= v^2/2g=(4ms)2^/2(9.81ms)=0.81m
The net peak crop water requirement for a scheme is 6.0 mm/day. The available moisture for the clay loam is 130mm/m and depletion is allowed up to around 46%. The root zone depth is 0.70 m. After how many days should irrigation take place to replenish the soil moisture?
a. 5
b. 6
c. 7
d. 8
c. 7
At Nabusenga surface irrigation schemes, it is assumed that conveyance efficiency and field canal efficiency both are 90% for concrete-lined canals continuous flow and that application efficiency is 50%. What is the overall irrigation efficiency?
a. 45%
b. 40.5%
c. 81%
d. 50.5%
b. 40.5%
Et=(0.9)(0.9)(0.5)=40.5%
A 21.6mm/day water requirement is equivalent to ___lps/ha
2.5lps/ha
The recent monsoon rain have posted a nearly uniform rainfall intensity of 30mm/hr. over a 1500ha watershed area in central Luzon. If the runoff coefficient is 0.15, what is the runoff in m3/sec?
a. 40.3 m^3/s
b. 23.5 m^3/s
c. 18.8 m^3/s
d. 11. 6 m^3/s
c. 18.8 m^3/s
Q=CIA=(0.15)(0.030m/hr)(1500ha (10,000m/23,600s)
=18.75m^/s
Three tanks are installed side by side in a field to measure the evapotranspiration of rice. Tank A is bottomless and is cropped. Tank B is bottomless but is uncropped. Tank C has bottom and is uncropped. If the water losses after 2 rainless days are as follows
Tank A – 15mm
Tank B – 9mm
Tank C – 5mm
The actual evapotranspiration is
a. 9.7 mm/day
b. 7.3 mm/day
c. 6.1 mm/day
d. 5.5 mm/day
ETa=(A−B+C)/2
=(15−9+5)/2
=5.5mmday
The farm water requirement is 2lps/ha, application efficiency is 75% and the conveyance efficiency is 80%. If the dependable flow is 2.5m3/s, the irrigable area is
a. 100 ha
b. 80 ha
c. 70 ha
d. 60 ha
a. 100 ha
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?
A3 m B. 4m C. 5 m D. 6 m
Solution:
b = 2 d tan (Ө/2)
= 2 (5) tan (45/2)
= 2 (5) tan (22.5)
= 2 (5) (0.41)
= 4.1 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?
A3.15 m B. 4.15 m C. 8.15 m D. 6.15 m
Answer: C
Solution:
b = 4 d tan (Ө/2)
= 4 (5) tan (22.5)
= 8.2 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?
A. 4.72 m B. 7. 42 m C. 2.47 m D. 7.24 m
Answer: A
Solution:
Ө = arctan (rise /run)
= arctan (1/2)
= 26.6º
b = 4 d tan (Ө/2)
= 4 (5) tan (26.6/2)
= 4 (5) tan (13.3)
= 4 (5) (0.236)
= 4.72 m
A trapezoidal canal has a bottom width of 2.5 m and its sides are inclined 60o with horizontal. It can carry water up to a depth of 3 m. S = 0.0008 and n = 0.03. Find the discharge in m3/s when flowing full. Use the Manning’s equation.
Given:
Base = 2.5m
z = 1√3=0.577
y = 3m
S = 0.0008
n = 0.03
14.60 m^3/s
A concrete lined canal is to convey water over a distance of 250 m from the well to a tomato farm. Drop in elevation is 0.5 m over the 250 m canal length and roughness coefficient, n, is 0.018.
a. Estimate the bottom width of a rectangular canal with a depth of flowing water of 0.25 m if the hydraulic radius is equal to the area of flow.
b. The velocity of the canal
a. 0.5
b. 0.62 m/s
What is the depth of flowing water in a trapezoidal canal with a side slope of 1:1 and base of 1.0 m if the stream velocity is 1m/s and the average discharge is 6m3/s.
Solution:
Area of trapezoidal canal is:
2 m
What is the water depth for a trapezoidal canal with the following known parameters:
Q = 0.09m3/sec
S = 0.001
b = y
n = 55
Side slope (z) = 1
Allowable Velocity = <0.75m/sec
0.30 m
Given bed slope=0.0003; Manning’s coefficient, n=0.03; b/d ratio=3.5; wetted perimeter, p=14; z=0.5. The velocity of flow along a trapezoidal canal is:
0.82 m/s
A rectangular lined canal will be used to irrigate 60 has. If a Francis weir of 0.4m crest will be used to control the flow, what would be the depth of water over the crest in order to supply 2lps/ha?
0.3 m
A farmer collected a soil sample 2 days after irrigation. The sample has a diameter of 5 in., height of 8 in. and the sample weighed 3000 g before drying and 2340 after drying. Bulk density is g/cc.
0.909 g/cm^3
the ratio of the void volume to the total soil volume (unitless)
porosity
the ratio of the dry weight of the soil to the total soil volume
bulk density
the ratio of the dry weight of the soil to the volume of the
soil particles
particle density
ratio of the bulk density of the soil with the
density of water; it is the ratio of the weight of soil to the weight of water with
volume equal to the total soil volume
Apparent Specific Gravity (As)
