Define crop yield and productivity. Flashcards
How do you take off a canal from a dam?
ESE 2017
Canal should be taken off tangentially from a
dam.
What are the methods to calculate capacities
of reservoirs?
• Relation between Inflow, outflow, and
storage data for a reservoir
• Fixing the reservoir capacity from the annual
inflow and outflow data
• Fixation of reservoir capacity with the help
of mass curves of inflow and outflow
• Fixation of reservoir capacity analytically
using sequent peak algorithm.
What are the types of flow over a Spillway?
In general, flow over the spillway is critical flow.
Can rainwater harvesting be used to prevent
floods?
Rainwater harvesting can be used to prevent
floods as well. Rainwater harvesting harmonizes the flow of water in drains.
What are the different methods used for the
dissipation of hydraulic energy of the water stored in dam?
Stilling basin type energy dissipators:
These are of two types viz.: Hydraulic jump type stilling basin
Stilling basin type energy dissipators:
These are of two types viz.: Hydraulic jump type stilling basin
o Hydraulic jump with horizontal apron
Hydraulic jump with sloping apron Jet diffusion type stilling basin
o Jet diffusion stilling basin o Interacting jet dissipators o Free jet stilling basin
o Hump stilling basin
At what stage will you tell that there is a flood
if you are standing beside a river? When standing
beside a river, if the water level crosses the danger mark of the river then it can
be said that flood has occurred.
What are the major factors to be considered for construction of dam in hilly regions?
Dam construction in hilly regions: The following factors need to be considered for construction of a dam in hilly region:
(a) Purpose of dam i.e. dam is to be
constructed for storage purpose or for hydro power generation or for irrigation etc.
(b) Number of beneficiaries to be served by the dam.
(c) Availability of hard rocks for abutments.
(d) The valley should be deep and narrow for
large storage volume.
(e) The area upstream of the dam should open in a large expense so that sufficient volume
for storage is available.
(f) Head available if the dam is to be used for
hydro power generation.
(g) Seismic characteristic of the area where
dam is to be located.
(h) Availability of approaches for the dam.
(i) Minimum dry weather flow of the river.
(j) HFL in the river reached in the past and
expected in future.
(k) Amount of precipitation in the catchment.
(I) Number of people which will get affected
by the construction of dam
(m) Impact of dam on environment i.e., EIA
(Environment Impact Assessment) studies.
(n) Design life of the dam.
What do you mean by drainage condition in retaining wall?
Drainage of water as a result of rainfall or other wet conditions is very important to the stability of a retaining wall. Without proper drainage, the backfill can become saturated, which has the
ing the pressure on the
offers the benefits of good drainage, easy
What is earthen dam?
Earthfill dam , also ca lled Earth Darn, or
Embankment Dam, built up by compacting successive layers of earth, using the most impervious materials to form a core and placing more permeable substances on the upstream and downstream sides
Differentiate among dam, barrage and weir.
ESE 2012, 2016, 2017
Dam is a barrier constructed to hold back water
and raise its level, forming a reservoir used to generate electric ity or as a water supply.
Barrage: It is an artificial barrier across a river or estuary to prevent flooding, aid irrigation or navigation, or to generate electricity by tidal power.
Weir: It is a low dam built ac ross a river to raise the level of water upstream to regu late its flow.
What precaution you will take while you are
constructing a dam?
These precautions must be taken in the
construction of dam
(a) Selection of darn site.
(b) Identification of earthquake prone area and structure and identification of earthquake-
related safety concerns.
(c) Development of a site-specific geo- technical, exploration program.
(d) Design of the foundation, dam, and appurtenant structures.
(e) Design of a system of instrumentation to monitor the performance of the dam,
foundation, and appurtenant structures.
(f) Development of an initial reservoir-filling and
surveillance plan and of reservoir drawdown criteria.
(g) Preparation of designer’s operating criteria and identification of special considerations
to be observed during construction and operation.
dual impact of increas
wall and lessening the resistance of the backfill material to sliding. Granular backfill material
(h) Provisions for the automatic, independent review by competent individuals of all
design decisions, methods, procedures, and results related to dam safety.
(i) Provisions to revise the design to make it
compatible with conditions encountered during construction.
What is economic height of dam?
ESE 2012
The economic height of a dam is that height of
the dam, corresponding to which, the cost of the dam per unit of storage is minimum.
What are the various forces acting on a
dam?
The most important forces are:
(a) Weight of dam
(b) Water Pressure
(c) Uplift
(d) Wave pressure
(e) Earthquake forces
(f) Silt pressure
What is the difference between big and small
dam?
Small dams:
(a) They serve the purpose of drinking water.
(b) Maintenance of small dam is cheaper.
(c) Small dams are part of water management
for big dams.
Big dams:
(a) Big dams run industries from its power generation.
(b) Super floods can only be controlled by big dams.
What is a Spillway?
ESE 2012, 2016, 2017
A spillway is a structure used to provide the
controlled release of flows from a dam or levee into a downstream area, typically the riverbed of the dammed river itself, they may be known as overflow channels. Spillways ensure that the water does not overflow and damage or destroy the dam.
What are Cofferdams and Check dams?
ESE 2013, 2016, 2017
A check dam is a small, sometimes temporary,
dam constructed across a swale, drainage ditch,
or waterway to counteract erosion by reducing water flow velocity.
A cofferdam is an enclosure built within, or in pairs across, a body of water and constructed to allow the enclosed area to be pumped out. This pumping creates a dry work environment for the work to be carried out.
What are the different types of Darn?
(ESE 2013, 2016, 2017) Ans.
Buttress Dam. • Coffer Dam. • Diversion Dam. • Embankment Dam, • Gravity Dam. • Hydropower Dam. • Industrial Waste Darn.
What is fish ladder and purpose of it?
ESE 2013, 2017
Migratory fishes (such as Hilsa in India) move from upstream to downstream in winter season in search of warm water and return to their origin upstream slightly before the monsoons. If no arrangement is made in the weir or darn for the fish to pass upstream then such migratory fishes are found to strike against the water current repeatedly in their effort to move up till death. This leads to large scale destruction of migratory aquatic species. But most types of fishes can travel upstream at 3 to 3.5 m/s. In general there is a head difference of about 5 to 6 m between the upstream of weir or dam and downstream water level in the river. If a simple opening is provided in such a weir or dam then velocity of flow will be too high. Thus a fish ladder is provided which dissipates the flow energy in such a manner so as to provide a smooth flow at sufficiently low velocity not exceeding 3 to 3.5 m/s. Fish ladder is accomplished by providing a narrow opening adjacent to the divide wall and provide suitable waffles or staggering devices in it. 8.18 What do you mean by weep hole?
