What are the advantages and disadvantages of Small Dams?
Note:- Please write the advantages and disadvantages separately.
Answers
Answer:
Advantages--
a) Irrigation
b) Electricity generation
c) Water supply for industrial and domestic purposes
d)Flood control
e) Amusement
f) Inland navigation
g) Fish breeding
____
Disadvantage
a)Natural flow of river is affected causing poor flow of sediments
b) Excessive sedimentation of the reservoir
c)Stream beds become rockier
d)Dam fragments a river thus making it difficult for aquatic fauna to migrate, and for spawning
Explanation:
Answer:
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Explanation:
Advantages
Maintenance cost is negligible.
They are specially suitable for deep steep valley conditions where no other dam is possible.
If suitable foundation is available, such dams can be constructed for very large heights.
Because they can be constructed in very large heights, they can store more amount of water.
If suitable separate place is not available for installation of spillways, they can be installed in the dam section itself.
This dam gives prior indication of instability. \If remedial measures are taken in time, unsafe dams may even be rendered safe.
Even if they cannot be made sale they give sufficient time for the people to move out the area likely to be submerged due to failure of the dam.
Silting rate of the reservoir can be reduced considerably by installing undersluices in the dam near the bed of the reservoir.
Sluices can be operated from time to time and silt may be scoured out of the reservoir.
They are not affected by very heavy rainfall. Earth dams cannot sustain very heavy rainfall because of heavy erosions.
Disadvantages
They are very costly in initial construction.
They take lot of time of construct.
They require skilled labour for construction.
Such dams can be constructed only on good foundation.
If height of the dam is to be raised, it cannot be done unless provision for it had been made in the construction of the lower part of the dam.
(B) Earthfill and Rockfill Dam.
Advantages
They can be constructed on any type of foundation
They can be constructed in comparatively less time.
They do notrequire skilled labour.
Initial cost of construction is low as locally available soils, and rock boulders are normally used.
Their height can be increased without any difficulty.
They are specially suitable for conditions where slopes of river banks are very flat.
Gravity dams under such conditions are not found suitable.
Disadvantages
They fail all of the sudden without giving any pre-warning.
Flood waters affect the dam safety.
Spillway have to be located independent of the dam.
They cannot be constructed as overflow dams.
They require continuous maintenance.
They cannot be constructed in narrow steep valleys.
They cannot withstand heavy rains unless properly protected.
They cannot be constructed in large heights.
The usual height is 30 m for which most of the earthen dams are constructed.