Quiz: Civil Engineering 21 Nov 2020

Quiz: Civil Engineering
Exam: RSMSSB-JEn
Topic: Irrigation & Water Resources

Each question carries 1 mark
Negative marking: 1/3 mark
Time: 10 Minutes

Q1. The equation for channel flow V = 0.55my0.64 was developed by
(a) Manning
(b) Lacey
(c) Kennedy
(d) Chezy

Q2. A water shed canal
(a) Is most suitable in hilly areas
(b) Avoids the cross drainage works
(c) Irrigates only one side
(d) Is generally aligned parallel to the contours of the area

Q3. The water stored in the reservoir below the minimum pool level is called
(a) Useful storage
(b) Dead storage
(c) Valley storage
(d) Surcharge storage

Q4. Coefficient of discharge of an ogee spillway
(a) Remains constant
(b) Depends on depth of approach and upstream slope
(c) Depends on downstream apron interference and downstream submergence
(d) Both (2) and (3)

Q5. The standard recording rain gauge adopted in India is of
(a) Weighing bucket type
(b) Natural syphon type
(c) Tipping bucket type
(d) Telemetry type

Q6. The duty of irrigation water for a given crop is maximum
(a) on the field
(b) at the head of the main canal
(c) at the head of the water-course
(d) None of these

Q7. If specific yield of particular sand is 30% and its porosity is 50%, then the specific retention of the sand will be
(a) 80%
(b) 55%
(c) 40%
(d) 20%

Q8. Calculate the seepage velocity of water through a permeable soil under a hydraulic gradient of 1/40. Take coefficient of permeability K = 1.2 × 10^(–2) m/s
(a) 48 × 10^(–2) m/s
(b) 3 × 10^(–4) m/s
(c) 33.3 × 10^(–2) m/s
(d) 4.8 × 10^(–4) m/s

Q9. Instantaneous unit hydrograph is a hydrograph of
(i) unit duration
(ii) unit rainfall excess
(iii) infinitely small duration
(iv) infinitely small rainfall excess
(a) (i) and (ii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (iii) and (iv)

Q10. Which of the following is not a form of precipitation?
(a) Snow
(b) Rain
(c) Hail
(d) Smog

SOLUTIONS

S1. Ans.(c)
Sol. As per Kennedy’s, the critical velocity of a channel is given by-
▭(V_C=0.55 my^0.64 )
Where, V_C= critical velocity
m = critical velocity ratio
y = depth

S2. Ans.(b)
Sol. A water shed canal or ridge canal aligned along the ridge line or water shed line. It can irrigate the area on both sides. It is constructed to avoid cross drainage works.

S3. Ans.(b)
Sol. The water stored in the reservoir below the minimum pool level is called dead storage. While Useful storage is the volume of water stored in a reservoir between the minimum pool and normal pool level.

S4. Ans.(d)
Sol. Coefficient of discharge of an ogee spillway is depends upon depth of approach and upstream slope as well as on downstream apron interference and downstream submergence.

S5. Ans.(b)
Sol. Natural syphon rain gauge is adopted as standard recording type rain gauge in India. It is also known as float – type gauge.

S6. Ans.(a)
Sol. Duty of water for a crop is the number of hectares of land irrigated by water supply over complete base period. It is maximum on the field.

S7. Ans.(d)
Sol. Given,
Specific yield (S_y) = 30%
Porosity (n) = 50%
Specific retention (SR) =?
S_y+S_R=n
30%+S_R= 50%
S_R=20%

S8. Ans.(b)
Sol. Given i= 1/40, K= 1.2×10-2 m/sec.
Seepage velocity (v) = ki
= 1/40×1.2×10^(-2)
= 3×10^(-4) m/sec

S9. Ans.(c)
Sol. Instantaneous unit hydrograph is a hydrograph of unit rainfall excess for infinitely small duration.
u(t)=1/i ds/dt
i= rainfall intensity
S= ordinate of S-curve
u(t)= ordinate of instantaneous hydrograph.

S10. Ans.(d)
Sol. There are some forms of precipitation-
– Rainfall
– Drizzle
– Glaze
– Snow
– Sleet
– Hails

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