Deck 8: Floods, Catchment, and Irrigation

Question 1

Interception losses are due to
i. evaporation
ii. transpiration
iii. stream flow
The correct answer is

A)only (i)
B)(i)and(ii)
C)(ii) and (iii)
D)(i), (ii) and (iii)

Answer 1

only (i)

Question 2

A 6 hours storm had 4 cm of rainfall and the resulting runoff was 2 cm. If

A)4.5 cm
B)6.0 cm
C)7.5 cm
D)9.0 cm

Answer 2

6.0 cm

Question 3

Which of the following methods is used to estimate flood discharge based on high water marks left over in the past ?

A)slope-area method
B)area-velocity method
C)moving boat method
D)ultra-sonic method

Answer 3

slope-area method

Question 4

To determine the discharge at a section in a stream from its rating curve, the required data are
i. slope of water surface at the section
ii. stage at the section
iii. current meter readings at the section
The correct answer is

A)(i) and (ii)
B)(ii) and (iii)
C)only (ii)
D)only (iii)

Question 5

The stage of river carrying a discharge of Q m7sec at a point is 10 m and slope of water surface is (1/4000). The discharge of a flood at the same point and same stage of 10 m with a water surface slope of(l/1000)willbe

A)V2 Q m³/sec
B)0.5 Q mVsec
C)2 Q m³/sec
D)4 Q m³/sec

Question 6

The stream which does not have any base flow contribution is called

A)perennial stream
B)intermittent stream
C)ephemeral stream
D)none of the above

Question 7

The flow-mass curve is graphical representation of

A)cumulative discharge and time
B)discharge and percentage probability of flow being equaled or exceeded
C)cumulative discharge, volume and time in chronological order
D)discharge and time in chronological order

Question 8

If the demand line drawn from a ridge in a flow mass curve does not intersect the curve again, it indicates that

A)demand cannot be met by inflow
B)reservoir was not full at the beginning
C)both (a) and (b)
D)none of the above

Question 9

The shape of recession limb of a hydrograph depends upon

A)basin characteristics only
B)storm characteristics only
C)both (a) and (b)
D)none of the above

Question 10

Instantaneous unit hydrograph is a hydrograph of
i. unit duration
ii. unit rainfall excess
iii. infinitely small duration
iv. infinitely small rainfall excess
The correct answer is

A)(i) and (ii)
B)(i)and(iv)
C)(ii) and (iii)
D)(iii) and (iv)

Question 11

For a catchment area of 120 km², the equilibrium discharge in m³/hour of an S-curve obtained by the summation of 6 hour unit hydro graph is

A)0.2 x 10⁶
B)0.6 x 10⁶
C)2.4 x10⁶
D)7.2 x10⁶

Question 12

A unit hydro graph has one unit of

A)rainfall duration
B)rainfall excess
C)time base of direct runoff
D)discharge

Question 13

The peak of a 4 hour flood hydrograph is 240 m³/sec . If the rainfall excess is 80 mm and base flow which is constant is 40 m³/sec, then the peak of 4-hours unit hydrograph will be

A)20 m³/sec
B)25 m³/sec
C)30 m³/sec
D)35 m³/sec

Question 14

To estimate the magnitude of a flood with a return period of T years, Gumbel's distribution method requires the following data pertaining to annual flood series
i. mean value
ii. standard deviation
iii. length of record
iv. coefficient of skew
The correct answer is

A)(i) and (ii)
B)(i),(ii) and (iii)
C)(i), (ii) and (iv)
D)(i), (ii), (iii) and (iv)

Question 15

For an annual flood series arranged in descending order of magnitude, the return for a magnitude listed at position period m in a total data N is

A)N/(m+l)
B)m/(N+l)
C)m/N
D)(N+l)/m

Question 16

If the risk of a flood occurring in the next 10 years is accepted to 10%, then the return period for design should be

A) 1 + 0.9°10
B) 1 - 0.9°10
C) 1/1?0.9?10
D) 1/1+0.9?10

Question 17

The crest level in a barrage is kept at a

A)low
B)high
C)moderate

Question 18

When the full supply level (F.S.L.) of the canal is much below the bed level of the drainage trough, then the cross drainage provided is called syphon aqueduct.

Question 19

A spoil bank is formed when the

A)canal has steel bed slope
B)canal section is too large
C)volume of excavation is in excess of the embankment filling
D)canal alignment is meandrous

Question 20

When the drain is over the canal, the structure provided is known as

A)aqueduct
B)super-passage
C)canal syphon
D)syphon aqueduct

Question 21

A levee on flood

A)increases the water surface elevation of the river at flood
B)decreases the surface slope of the stream above the leveed portion
C)increases the velocity and scouring action through leveed section
D)all of the above

Question 22

The primary cause of meandering is the excess of total charge during floods, when excess of turbulence is developed.

Question 23

In order to estimate the high flood discharge in fan-shaped catchment, the formula used is

A)Dicken's formula
B)Ryve's formula
C)Inglis formula
D)Fanning's formula

Question 24

The capacity of escape channel should not be less than

A)20%
B)30%
C)40%
D)50%

Question 25

The whole period of cultivation from the time when irrigation water is first supplied for preparation of the ground to its last watering before harvesting, is called

A)base period
B)crop period
C)kor period
D)none of these