300+ REAL TIME Irrigation Engineering Objective Questions & Answers 2023

250+ TOP MCQs on Water Logged Reclamation – Surface or Open Drainage and Answers

Irrigation Engineering Multiple Choice Questions on “Water Logged Reclamation – Surface or Open Drainage”.

1. The land is made to be sloped towards the ditches.
a) True
b) False
Answer: a
Clarification: Open ditches are constructed in fields to remove the excess rain water falling in the ground or excess irrigation water applied to the fields. So, therefore for collection of these waters the land is sloped towards these ditches.

2. How many types of structures can be constructed in the fields to remove excess waters?
a) 5
b) 2
c) 3
d) 4
Answer: c
Clarification: Structures like open ditches, fields drains, and other related structures like artificial pipes etc can be constructed in the fields to remove excess waters from heavy rainfalls and excess irrigation.

3. What is the name given to the drains used in depressions?
a) Shallow Surface Drains
b) Deep Surface Drains
c) Open Drains
d) Drains
Answer: a
Clarification: Shallow surface drains are those types of open drains constructed in depressions on the fields to remove excess irrigation water, and storm water.

4. Shallow surface drains are connected to outlet drains.
a) True
b) False
Answer: a
Clarification: The shallow surface drains are in turn connected to the outlet drains, which are large enough to carry the maximum flood water of the catchment area from the shallow drains, and even from underground tile drains.

5. What is the cross sectional shape of shallow surface drains?
a) Triangular Shape
b) Circular Shape
c) Rectangular Shape
d) Trapezoidal Shape
Answer: d
Clarification: Since the shallow surface drains are designed to carry normal storm water and excess irrigation water. These are designed for normal runoff from the storm water, but we have to take excess irrigation into the account. So, for maximum discharge the shallow surface drains are given a trapezoidal cross sectional shape.

6. Which type of open drains would be fully operative only in rainy season?
a) Shallow Surface Drains
b) Deep Surface Drains
c) French Drain
d) Drains
Answer: b
Clarification: These drains carry both discharge from shallow surface drains and the seepage water from underground. To carry the seepage water from underground, a cunnette of about 0.6 m depth is provided at the center of the drain. The cunnette is lined void weed growth, and to withstand high velocities. It is fully operative only in rainy season because otherwise the flow will be confined in the cunnette only.

7. What structure is constructed to carry back into the underground?
a) Land Grading
b) Random Field Drains
c) Surface Inlet
d) Open Drains
Answer: c
Clarification: Surface inlets are the structures constructed to carry the pit water back into the subsurface. The materials used in the construction are cast iron pipe or manhole of bricks or monolithic concrete.

8. What type of system does the diagram represent?

a) Drains
b) French Drain
c) Deep Surface Drain System
d) Random Field Drain System
Answer: d
Clarification: This represents a series of depressions connected with shallow surface drains which are in turn connected to lateral and main outlet drains. So, therefore this diagram represents a system of random field drain system.

9. In surface inlet what is provided to deal with trash?
a) Cunnette
b) Beehive Grate
c) Surface Inlet
d) Blind Inlet
Answer: b
Clarification: The bottom of the surface inlet a concrete collar is provided around the intake onto the prevent growth of vegetation or weeds. And to prevent the trash from entering the tile a beehive grate is provided on the top of the riser.

10. Which type of drains is used for small quantity of waters removal?
a) Blind Inlet
b) Shallow Surface Drains
c) Deep Surface Drains
d) Open Drains
Answer: a
Clarification: When the water quantity to be removed from the pits or depressions is small, then a blind inlet or also named as French drain is constructed over the tile drain. These drains are constructed by back filling with graded materials in the trench of the tile drain.

250+ TOP MCQs on Sediment Transport – Bed Load and its Measurement and Answers

Irrigation Engineering Multiple Choice Questions on “Sediment Transport – Bed Load and its Measurement”.

1. On which factor does the movement of bedload depends?
a) Velocity of Flow
b) Type of Flow
c) Depth of Flow
d) Width of the River
Answer: a
Clarification: Bedload is a sediment load, and it moves by the actions like rolling, sliding and hopping which in turn depend on the velocity of flow. The bed load remains in the bottom layers of the flow.

2. Commonly the bed load is 10% of total suspended load.
a) True
b) False
Answer: a
Clarification: Sometimes bed load is estimated to be in between 3 to 25% of the total suspended load, depending upon the reflexes of the sediment to forces from the sectors like physical, chemical, and biological. In between this percentage we commonly take bed load is 10% of total suspended load.

3. What type of force is completely responsible for the bedload movement?
a) Forces of Turbulence
b) Drag Force
c) Capillary Force
d) Gravity Force
Answer: b
Clarification: Generally we know that bedload is a type of sediment which moves adjacent to the bed of the channel. Shear stress (τ_o) is responsible for this movement of bedload along the bed if the channel, which is developed by the flowing water along the channel bed. This shear force is called drag force or tractive force.

4. Which type of force is needed for suspension of suspended load in flowing water?
a) Capillary Force
b) Drag Force
c) Forces of Turbulence
d) Gravity Force
Answer: c
Clarification: Suspended load is a sediment load, but remains in suspension in the flowing water of the channel. The forces which cause this suspension are the forces of turbulence, which are generated by the flow of the channel itself.

5. A part of tractive force does not have any part in transporting the bed material, i. e bed load.
a) True
b) False
Answer: a
Clarification: In order to transport the bed load the tractive force (τ_o) should exceed the critical tractive force (τ_c), therefore the rate of movement of bedload becomes a function of (τ_o – τ_c). But, as soon as the sediment starts moving it is opposed by the ripples generated by the channel bed, and to overcome these ripples a large part of tractive force is lost and cannot be used again. So, this part of the force does not have any part in transporting the bed load.

6. Given that the bed slope of a channel is 1 in 2000 and the discharge is 60 cumecs. The depth of the channel is fixed and is given as 2 m. The tractive force needed for the movement of bedload is? Take critical velocity ratio as 1.1.
a) 8.89 N/m³
b) 8.87 N/m³
c) 8.85 N/m³
d) 8.83 N/m³
Answer: d
Clarification: Critical velocity (V_o) = 0.55my^0.64
= 0.55 x 1.1 x (2)^0.64
= 0.943 m/sec
Area = Q / V_o = 60 / 0.943 = 63.63 m² (Given Q = 60 cumecs)
A = y (b + y (1/2)) (y = depth, b = base width)
63.63 = 2(b + 1) (for side slope as (1/2:1/2H:V))
b = 30.82 m
Perimeter (P) = b + √5y = 30.82 + 2 x √5
P = 35.3 m
R = A/P = 63.63 / 35.3 = 1.8 m (R = hydraulic mean depth)
Now, tractive force (τ_o) = γ_wRS = 9.81 x 10³ x 1.8 x (1/2000) (γ_w = 9.81 x 10³ N/m³)
= 8.83 N/m³.

7. What cause is prime responsible for the heavy movement of water from main canal to branch canal?
a) Existence of Favorable Gradient
b) Velocity of Flow
c) Type of Flow
d) Depth of the Canal
Answer: a
Clarification: When a branch canal is connected to the main canal, the branch canal starts taking water discharge which reduces the discharge in main canal thereby reduces sediment load capacity. This leads to the deposition of sediment load which further diverts the flow towards branch canal. This process continues till all the water in the main canal gets discharged into branch canal. The prime cause of this phenomenon is due to the existence of favorable gradient in the branch canal.

8. Water in which condition or state carry a maximum amount of sediment?
a) Uniform State
b) Vapor State
c) Floods
d) Ice
Answer: c
Clarification: According to Einstein’s equation (q_b/q≼qS²/d^3/2), the sediment carrying capacity of the channel depends upon the discharge per unit width. Therefore, this gives that floods can carry more amount of sediment than any other state of water because the discharge per unit width of channel is maximum in case of floods. Most of the annual sediment load is done by floods.

9. What minimum value of shear stress is needed to move the sediment?
a) Critical Velocity Ratio
b) Critical Shear Stress
c) Critical Velocity
d) Drag Force
Answer: b
Clarification: Generally in nature, any two moving bodies oppose each other due to internal presence of friction between them. Here as the sediment load moves along the bed of the channel, then internal friction is developed between them depending upon the soil. Therefore to overcome this friction a minimum value of shear stress is needed. This minimum value is called critical shear stress (τ_c).

10. Design a channel carrying a 30 cumecs. The median grain diameter is taken as 0.5 mm. The bedload concentration is 60 p.p.m by weight. Use Lacey’s Regime perimeter and Meyer-peter’s formulas.
a) B = 26 m, S = 1/5600, y = 1.25 m
b) B = 22 m, S = 1/5800, y = 1.55 m
c) B = 24 m, S = 1/5500, y = 1.45 m
d) B = 25 m, S = 1/5700, y = 1.35 m
Answer: d
Clarification: Quantity of bed load transported by weight = 40/10⁶
Quantity of bed load transported per second = 40/10⁶ (30 x 9.81 x 1000) = 11.8 N/sec
Lacey’s Regime perimeter = 4.75 x √Q = 26.03 m
Let us take channel bed width (B) as 25 m
Bed load per unit width = g_b = 11.8 / 25 = 0.472 N/m/sec
Meyer Peter equation –
g_b = 0.417 x [τ_o(n’/n) – τ_c]^3/2
n’ = (1/24) x (0.5)^1/6
= 0.011
n = 0.02
n’/n = 0.55
τ_c = 0.687 x da = 0.687 x 0.5 = 0.3435 N/m²
g_b = 0.417 [9.81 x 1000 x RS x (0.55)^3/2 – 0.3435]^3/2
RS = 0.0002
Manning’s equation –
Q = 1/n x R^2/3 x S^1/2
R^2/3 x S^1/2 = 0.6
S = 0.0002/R
S = 1/5700
R = 1.15 m
Now P = 25+y√5, A = 25y + y²/2 for trapezoidal channel of 1/2:1 slopes
R = A/P = (25+√5y)/ (25+y²/2) = 1.15
From this y = 1.35 m
Therefore B = 25 m, y = 1.35 m, S = 1/5700.

250+ TOP MCQs on Water Requirements – Duty and Delta of a Crop and Answers

Irrigation Engineering Multiple Choice Questions on “Water Requirements – Duty and Delta of a Crop”.

1. What is the time interval between two consecutive watering called?
a) Crop Period
b) Period
c) Base Period
d) Rotation Period
Answer: d
Clarification: Every type of crop requires different amount of water for its complete growth in certain fixed intervals of time. The time interval between two consecutive intervals is called a rotation period.

2. What is total depth of water, for complete growth of crop called?
a) Triangle
b) Delta
c) Duty of Water
d) Rotation Period
Answer: b
Clarification: The total quantity of water required by the crop for its complete growth can be expressed in terms of depth of water standing on the field. This total depth expressed in cm is called delta.

3. Duty of water helps in the work out of discharge required for designing the channel.
a) True
b) False
Answer: a
Clarification: Duty of water gives a relation volume of water required and the area of irrigated crop. So, in this way if we know the area of crop irrigated we can know discharge required for the channel.

4. What is the name of duty called as in direct irrigation?
a) Flow Duty
b) Quantity Duty
c) Duty
d) Delta
Answer: a
Clarification: When direct irrigation is used, then the units of duty, always expressed in hectares/cumec. Then duty is called flow duty.

5. Which type of period is slightly more than its counterpart period?
a) Crop Period
b) Period
c) Base Period
d) Rotation Period
Answer: a
Clarification: Crop period is time period between the instant of sowing to its harvesting. Base period is the time period between the first watering of crop to its final watering before harvesting.

6. Flow irrigation system has lower duty than lift irrigation system.
a) True
b) False
Answer: a
Clarification: In lift irrigation system due to the commanded area of each well near to it, gives a high value of duty when compared to flow irrigation system.

7. Which type of units is used to define high and low duty?
a) Hectare-meters
b) Hectares/cumec
c) Meters
d) Centimeters
Answer: b
Clarification: According to the number of hectares/cumec, if the irrigated area is large or small then it is called high or low duty respectively.

8. Which type of area is large in quantity compared to others?
a) Gross Commanded Area (G.C.A)
b) Culturable Commanded Area (C.C.A)
c) Culturable Cultivated Area
d) Culturable Uncultivated Area
Answer: a
Clarification: Gross Commanded Area (G.C.A) is the sum of Culturable Commanded Area (C.C.A) and unculturable area. Again Culturable Commanded Area (C.C.A) is divided into the sum of culturable cultivated and culturable uncultivated areas. Therefore, Gross Commanded Area (G.C.A) is a large quantity.

9. In what type of area crop is not sown for a particular season?
a) Gross Commanded Area (G.C.A)
b) Culturable Commanded Area (C.C.A)
c) Culturable Cultivated Area
d) Culturable Uncultivated Area
Answer: d
Clarification: This type of area is not kept under cultivation because, to restore the fertility of the soil, to provide pasture land for animals, to prevent water logging in the land.

10. Given that, a particular irrigation field has C.C.A as 200 hectares, out which 150 hectares of land is cultivated for rabi season and 100 hectares of land is cultivated for kharif season. What is the intensity of irrigation for each season?
a) 50%, 100%
b) 120%, 60%
c) 75%, 50%
d) 150%, 75%
Answer: c
Clarification: For rabi season:
Intensity of irrigation = (150/200) x 100
= 15 x 5
= 75%
For kharif season:
Intensity of irrigation = (100/200) x 100
= 0.5 x 100
= 50%.

11. Given that a particular crop requires about 20 cm depth of water at an interval of 40 days, and the base period is 400 days. Find the delta for the crop? Now using this delta find the duty of water for the crop?
a) 150 cm, 1150 hectares/cumec
b) 180 cm, 1825 hectares/cumec
c) 200 cm, 1728 hectares/cumec
d) 195 cm, 1920 hectares/cumec
Answer: c
Clarification: Given that base period is 400 days at an interval of 40 days. This number of waterings as = 400/40 = 10
Now delta = 10 x 20 = 200 cm.
Now we have relation between delta and duty as –
Delta = (864B)/D
B = base period, D = duty
200 = (864 x 400)/D
D = 864 x 2 = 1728 hectares/cumec.

12. It is said that a particular type of crop requires a depth of 6 cm of water every 24 days and the crop period is 168 days. Find the delta of the crop?
a) 50 cm
b) 42 cm
c) 20 cm
d) 95 cm
Answer: b
Clarification: Assume that crop period is equal to base period. So, given base period is 168 days, and it requires watering for every 24 days. Therefore number of waterings for entire cultivation = (168/24) = 7
Each watering needs 6 cm depth of water. So, therefore total depth of water required in 168 days = 7 x 6 = 42 cm.

13. How can we improve the duty of water?
a) Lining of Canals
b) Construction of Weir
c) Construction of Dam
d) Check Dams
Answer: a
Clarification: By lining of canals, carrying irrigation supplies we can reduce seepage and evaporation losses. Therefore reducing the field requirement of water increases the duty.

14. Which factor directly affects the duty of water?
a) Type of Crop
b) Useful Rainfall
c) Type of Soil
d) Canals
Answer: b
Clarification: If the rainfall useful is for the growth of crops, then more the rainfall less will be the requirement of water for the growth of crops and more will be the duty of irrigation water.

15. At which point in the entire canal system the duty of water will be more?
a) Head of the Water-course
b) Head of the Minor
c) Head of the Distributary
d) Head of the Branch
Answer: a
Clarification: As water flows from river to subsequent parts of the canal system some water losses takes place due to evaporation, and percolation. Due to this, the duty of water goes on increasing from starting point of canal system till its end point. Therefore, the duty of water is more at the last point of the system, i.e head of the water-course.

250+ TOP MCQs on Principal Components of a Hydro Electric Scheme and Answers

Irrigation Engineering Multiple Choice Questions on “Principal Components of a Hydro Electric Scheme”.

1. Forebay provides temporary storage before the water goes to the turbine. Following perform the function of forebay ____________________
a) river
b) tailrace channel
c) reservoir
d) approach channel
Answer: c
Clarification: The reservoir itself acts as a forebay when it is constructed by building a dam. The water is taken to the powerhouse directly from the reservoir through penstocks. Following are some functions of forebay:
• To temporarily store water and to meet the instantaneous demand
• Absorbs the short interval variations and fluctuations.

2. The surge tank serves which of the following purposes?

i. It allows the sediment to settle down
ii. It prevents debris from entering powerhouse
iii. It controls pressure variations in pipelines
iv. It regulates flow in the pipelines

a) i and ii
b) ii and iii
c) iii and iv
d) i, ii and iii
Answer: c
Clarification: The cylindrical chamber which is connected to the penstocks and open to the atmosphere is the simplest one. It serves the following functions i.e. to reduce the pressure fluctuations in the pipe and helps in eliminating additional water hammer pressure.

3. Identify the correct statement in regard to hydropower.
a) Hydropower stations are generally labour-oriented
b) The gestation period for hydro-power plant is usually small
c) The hydro generators give high efficiency over a wide range of load
d) In a hydropower scheme, the firm power is usually high as compared to tidal power
Answer: c
Clarification: Hydroelectric power plants are the most efficient means of producing energy and the efficiency of today’s hydroelectric plant is about 90%. Large hydropower plants usually have a gestation period of about 7 years whereas for smaller plants it is 2 to 5 years.

4. To avoid the possible damage to the wicket gates and turbine runners _________________ is provided.
a) trash racks
b) surge chamber
c) floating boom
d) racks and trolley arrangement
Answer: a
Clarification: Intakes should be provided with trash racks so as to prevent the entry of debris into the penstocks or to prevent choking up of the nozzles of the impulse turbines. Trash racks are made up of thin flat steel bars placed 10 to 30 cm apart and the permissible velocity of water entering these is 0.6 to 1.6 m/s.

5. In case of long penstocks, ___________________ is generally provided so as to absorb water hammer pressure.
a) trash racks
b) surge chamber
c) floating boom
d) racks and trolley arrangement
Answer: b
Clarification: The surge tank is mostly employed in a water power plant or in a large pumping plant to control the pressure variations resulting from rapid changes in the flow. It is done by admitting a large mass of water in the surge tank otherwise it would have flown out of the pipeline and returns to the tank due to closure of pipe end.

6. Sharp bends must be avoided in penstocks while designing components of the hydroelectric scheme.
a) True
b) False
Answer: a
Clarification: Sharp bends cause loss of head and requires special anchorages. It may be buried under the ground or kept exposed. The penstock can be replaced by constructing a tunnel through a hill if a considerable saving in length can be gained.

7. The retarding and accelerating heads are developed more promptly in ________________
a) simple surge tank
b) restricted orifice surge chamber
c) differential surge chamber
d) multi surge chamber
Answer: c
Clarification: The differential surge chamber has a central riser pipe in addition to the main outer tank and the retarding and accelerating heads are developed more promptly. The capacity of a different type of surge chamber may be less than that of a simple elementary type for a given amount of stabilizing effect.

8. The correct sequence in the direction of the flow of water for installations in a hydropower plant is _______________________
a) Reservoir, Surge tank, Turbine, Penstock
b) Reservoir, Penstock, Surge tank, Turbine
c) Reservoir, Penstock, Turbine, Surge tank
d) Reservoir, Surge tank, Penstock, Turbine
Answer: b
Clarification: The main components of a hydropower plant is Forebay, intake arrangement, Penstock, Surge tank, turbines and generators, powerhouse and tailrace. The water is taken from a reservoir or forebay and is taken down to the powerhouse by penstock. A surge tank is fitted at some opening made on a penstock to receive the rejected flow when the pipe is suddenly closed.

250+ TOP MCQs on Rock Fill Dams – Seepage Control Through Foundations and Answers

Irrigation Engineering Multiple Choice Questions on “Rock Fill Dams – Seepage Control Through Foundations”.

1. During the maintenance of an earthen dam, the apparent seepage through the foundation of the dam is best taken care of by providing ______________________
a) chimney drain
b) rock toe
c) drain trench along the downstream toe
d) upstream impervious cut-off
Answer: c
Clarification: Cut-off can be provided only during construction. If seepage appears afterward, a drain with an inverted filter along the toe line is provided to collect soil-free water to check piping action.

2. The base width of a rock-fill dam in comparison to that of an earthen dam is _______________
a) much larger
b) much smaller
c) sometimes large sometimes smaller
d) almost equal
Answer: b
Clarification: Rock-fill dams are less flexible than earthen dams, their foundation requirements are more rigid than those of earthen dams which can be constructed on any type of foundation. Since the steeper slopes are used in rock-fill dams and the base width is quite less.

3. On moderate foundations and particularly in seismic areas, the type of dam which can preferably be considered for construction is ___________________
a) masonry gravity dam
b) earthen dam
c) rock-fill dam
d) arch dam
Answer: c
Clarification: Rock-fill dams provide high resistance to seismic forces due to their flexible character. They are liable to large settlements which may lead to cracking of concrete membrane.

4. According to Terzaghi, the ratio of D₁₅ of filter to D₁₅ of base material should be _____________
a) > 5
b) < 4
c) 4 to 5
d) < 5
Answer: c
Clarification: Terzaghi provided a rational approach to the design of filters. The following filter criteria should be satisfied-
D₁₅ of filter / D₈₅ of base materials < 4 to 5 < D₁₅ of filter/ D₁₅ of base materials
The filters should be such that neither the embankment nor the foundation material can penetrate and clog the filters.

5. Which of the following is not provided in order to control the possibility of sand boiling?
a) Relief wells
b) Drain trenches
c) Vertical cut-offs
d) Berms
Answer: c
Clarification: There is a possibility that the water may boil up near the toe of the dam when large scale seepage takes place through the pervious foundation overlain by a thin less pervious layer. Relief wells or drain trenches and d/s berms beyond the toe of the dam are all provided to control sand boiling.

6. The seepage forces within the filter are controlled up to permissible small magnitudes when the ratio of D₁₅ of filter to D₁₅ of base material is ___________________
a) between 5 to 40
b) less than 5
c) between 5 to 20
d) less than 4
Answer: a
Clarification: When the ratio does not exceed 4 to 5, the base material is prevented from passing through the pores of the filter. When this ratio is more than 5 and less than 40, the seepage forces within the filter are controlled up to permissible small magnitudes.

250+ TOP MCQs on Reservoirs and Answers

Irrigation Engineering Multiple Choice Questions on “Reservoirs”.

1. A dam reservoir which is not provided with gate controls on its spillway and other sluices is called ________________
a) detention dam
b) storage reservoir
c) retarding basin
d) flood control reservoir
Answer: c
Clarification: Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets. The retarding basin is the one with uncontrolled and ungated outlets. The cost of gate installation is saved and there are no gates hence, the possibility of human error and negligence in their operation is eliminated.

2. A hydel power project has been envisaged to serve the water supply and irrigation needs of the area at its inception stage. The dam reservoir so constructed is known as __________________
a) multipurpose reservoir
b) single-purpose reservoir
c) distribution reservoir
d) retarding reservoir
Answer: a
Clarification: A reservoir planned and constructed to serve various purposes together is a multipurpose reservoir. It is designed to protect the downstream areas from floods, to conserve water, irrigation, industrial needs, hydroelectric purposes, etc. Bhakra dam and Nagarjuna Sagar dam are important multipurpose dams.

3. A dam reservoir catering to flood control, irrigation, and water supply basically designed for irrigation alone is a _______________-
a) multipurpose reservoir
b) single-purpose reservoir
c) distribution reservoir
d) retarding basins
Answer: b
Clarification: A reservoir planned, designed and constructed for one purpose is called a single purpose reservoir whereas a reservoir planned and constructed to serve various purposes together is a multipurpose reservoir. A small storage reservoir constructed within a city water supply system is called distribution reservoir

4. Which reservoir is also known as Mitigation reservoir?
a) Conservation reservoir
b) Flood control reservoir
c) Multipurpose dam
d) Storage reservoir
Answer: b
Clarification: A flood control reservoir protects the downstream areas by storing a portion of the flood flows to minimize the flood peaks. The entire inflow entering the reservoir is discharged or gradually released to recover the capacity for the next flood. It is also called as a mitigation reservoir.

5. A reservoir having gates and valves installation at its spillway and at its sluice outlets ___________
a) storage reservoir
b) retarding basin
c) both storage and retarding reservoir
d) distribution reservoir
Answer: a
Clarification: Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets whereas retarding basin is the one with uncontrolled and ungated outlets. It provides more flexibility in operation and better control.

6. Which reservoir is helpful in permitting the pumps or the water treatment plants to work at a uniform rate?
a) Storage reservoir
b) Detention reservoir
c) Multipurpose reservoir
d) Distribution reservoir
Answer: d
Clarification: A small storage reservoir constructed within a city water supply system is called a distribution reservoir. It stores water during hours of no demand or less demand and supply water from their storage during the critical time of maximum demand.

7. In which of the following reservoir the flood crest downstream can be better controlled and regulated properly?
a) Distribution reservoir
b) Multipurpose reservoir
c) Storage reservoir
d) Retarding reservoir
Answer: c
Clarification: Storage reservoirs are preferred on large rivers and require better control. It is provided with gated spillway and sluiceways for more flexibility of operation, better control and to increase the usefulness of the reservoir.

8. What are the types of flood control reservoirs?
a) Multipurpose reservoir and Single purpose reservoir
b) Storage reservoir and retarding reservoirs
c) Distribution reservoir and Storage reservoir
d) Distribution reservoir and multipurpose reservoir
Answer: b
Clarification: There are two basic types of flood-mitigation reservoirs i.e. storage reservoir and retarding reservoirs. Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets whereas the retarding basin is the one with uncontrolled and ungated outlets.

9. As the reservoir elevation increases, the outflow discharge increases.
a) True
b) False
Answer: a
Clarification: When floods occur the reservoir gets filled and discharges through sluiceways and the water level goes on rising until the flood has subsided. The inflow becomes equal or less than the outflow. The water gets completely withdrawn until the stored water is completely discharged.

10. The maximum discharging capacity of a retarding reservoir should not be equal to the maximum safe carrying capacity of the channel downstream.
a) True
b) False
Answer: b
Clarification: Since the retarding reservoir is not always filled much of the land below the maximum reservoir level will be submerged only temporarily and occasionally. The automatic regulation of outflow depends upon the availability of water. The maximum discharging capacity should be equal to the maximum safe capacity of the channel d/s.