MCQ
21. Seepage through embankments in an earthen dam is controlled by
Drainage filters
Relief wells
Drain trenches
Provision of downstream berms
22. The quantity of water retained by the sub-soil against gravity, is known
Yield
Porosity
Specific yield
Specific retention
23. To determine the discharge at a section in a stream from its rating curve, the required data are (1) Slope of water surface at the section (ii) Stage at the section (ii) Current meter readings at the section The correct answer is
(i) and (ii)
(ii) and (ii)
Only (ii)
Only (iii)
24. Indian Meteorological department uses the standard gauges whose collectors have apertures of
50 or 100 sq. cm area
100 or 150 sq. cm area
100 or 200 sq. cm area
250 or 500 sq. cm area
25. The critical depth in a channel can be produced
By raising the bottom of the channel
By lowering the bottom of the channel
By decreasing the width of the channel
Both (a) and (c) of above
26. 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, peak of 4hours unit hydrograph will be
20 m3/sec
25 m3/sec
30 m3/sec
35 m3/sec
27. The main function of a divide wall is to
Control the silt entry in the canal
Prevent river floods from entering the canal
Separate the under-sluices from weir proper
Provide smooth flow at sufficiently low velocity
28. The main cause of meandering is
Presence of an excessive bed slope in the river
Degradation
The extra turbulence generated by the excess of river sediment during floods
None of the above
29. Infiltration capacity of soil depends upon
Number of voids present in the soil
Shape and size of soil particles
Arrangement of soil particles
All the above
30. Hydrograph is a graphical representation of
Surface run off
Ground water flow
Rain fall
Discharge flowing in the river
31. Which of the following spillways is least suitable for an earthen dam?
Ogee spillway
Chute spillway
Side channel spillway
Shaft spillway
32. The run off a drainage basin is
Initial recharge + ground water accretion + precipitation
Precipitation ground water accretion + initial recharge
Precipitation ground water accretion + initial recharge
Precipitation ground water accretion – initial recharge
33. the exit gradient in the absence of a downstream cut-off is
Unity
Infinity
Very large
34. Which of the following can be used as a meter fall?
Vertical drop fall
Flumed glacis fall
Unflumed glacis fall
All of the above
35. The major resisting force in a gravity dam is
Water pressure
Wave pressure
Self-weight of dam
Uplift pressure
36. In India the recording type rain gauge generally used, is-
Weighing type
Tipping type
Float recording type
None of these
37. In the derivation of Thiem's formula, Q = (S1- S2)/[2.3 log10(/) the following assumption is not applicable
The aquifer is homogeneous and isotropic
Flow lines are radial and horizontal
The slope of the water surface is too small
The well has been sunk up to the surface of the unconfined aquifer
38. Pick up the correct statement from the following:
Absolute humidity at a given temperature is equal to weight of moisture present in a unit volume.
Relative humidity is the ratio of actual vapour pressure and saturation vapour pressure at the same temperature.
Relative humidity is the ratio of the weight of the vapours present per unit volume to the weight of vapours which could be contained at the same temperature when fully saturated.
All the above
39. For the estimate of high floods in fan-shaped catchment, the formula used is
Dicken's formula
Ryve's formula
Inglis formula
None of these
40. The net speed under which the turbine reaches its peak efficiency is called
Design speed
Rated speed
Gross speed
Operating speed