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Presentation
On
Site Selection and Investigations for SHP
Dr. S.K.Singal
Alternate Hydro Energy Centre
IIT Roorkee
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TYPE OF SCHEMES
RUN OF RIVER
No storage.
The output is subject to instantaneous flow.
Reliability of discharge and geological conditions should be ensured.
CANAL BASED
Utilizes the fall and flow in the canals.
May be planned in main canal or in bye-pass canal.
Nearby drops should be clubbed in existing canals.
In canals under planning concentrated drops should be considered.
DAM BASED
Dam toe schemes are most common in India.
Water stored during monsoon is utilized for power generation.
PUMP STORAGE
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Upper reservoir
Lower reservoir
Pumped storage
power plant
Pumping
Generating
Pumped Storage Scheme Configuration
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Diversion and Intake structure
Desilting chamber
Water conductor system Forebay/balancing reservoir
Penstock
Surge tank
Power house
Turbine, generator and controls
Tail Race
Switchyard
COMPONENTS OF SMALL HYDROPOWER SCHEME
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INVESTIGATIONS
Investigation Stages
1. Reconnaissance level (preliminary/PFR)
2. Feasibility/Detailed level (pre-investment/DPR)
3. Execution
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RECONNAISSANCE LEVEL
At this level of investigations following should be
determined
Hydrological survey
Topographical survey
Geological survey
Power load demand assessment
Socio- economic survey
Head and discharge.
Technical feasibility of the project.
Identification of critical issues and their possible
solutions.
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FEASIBILITY/DETAILED PROJECT
REPORT-INVESTIGATIONS
Hydrological survey
Topographical survey
Geological surveyPower load demand assessment
Socio- economic survey
Meteorological survey
Environmental survey
Survey for construction material
Power Evacuation Line Survey
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DURING AND FOR EXECUTION
STAGE Sub soil exploration/geo-technical investigation for knowing
soil parameters for structural designs
Setting of the pillars with levels for controls of levels for
excavation and structure
Testing of construction material
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TOPOGRAPHICAL SURVEY
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DETERMINATION OF HEAD
By altimeter
By GPS
By Dumpy level
By total station
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Distances
Angles
Directions
Elevations
Coordinates
TOPOGRAPHICAL
SURVEYS
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RUN-OF-RIVER: River with rapids and
drops
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RUN-OF-RIVER: River with mild slope
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LAYOUT PLAN OF RUN-OF-RIVER
SITE
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L-SECTION OF RIVER
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DETERMINATION OF HEAD
By altimetervery approximate
By GPS approximate
By Engineering level reasonable
Theodolite and Total Station accurate
Map very rough
Water filled tube crude but accurate
O O OG S O A
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METHODOLOGIES FOR HEAD
ESTIMATION1. USING DETAILED MAPS
Detailed topographic maps are useful for locating potential sites andfor obtaining a rough estimate of head levels.
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2. WATER-FILLED TUBE AND ROD
METHOD
This method is suitable for low-head sites. It is reliable, reasonably
accurate and inexpensive.
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ENGINEERS LEVEL
A telescope mounted so that it can be levelled tomake the axis horizontal only
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3. VERNIER THEODOLITE
TOTAL STATION
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TOTAL STATION
Main Body
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CONTOUR MAP OF PROJECT SITE
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TOTAL POINTS COLLECTED
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Global Position System
HANDHELD
MOUNTED
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FLOW MEASUREMENT
Velocity-area method
Weir method
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RECTANGULAR NOTCH
Q = 1.8 (L-0.2H) H3/2
Where,Q is discharge in cumecs
L is the length of the rectangular notch.
H is the height of water in notch
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V - NOTCH
Q = 1.417 H5/2
Where,Q is discharge in cumecs
H is the height of water meters
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AREA VELOCITY METHOD
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FLOW MEASUREMENT OF
TURBULENT STREAM
InstrumentFlow Stream
RangeUpto 4000 l/s
Accuracy1% PrincipleConductivity of the water
Q = M/(K x A) cumec
M = Mass of salt (Kg)K = Conversion factor (Kg/m3/ohm-1)
A = Area under curve (ohm-1S)
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Time (Seconds)
Cond
uctivity
(10ohm
)
-6
-1
Area underCurve
Back ground Conductivity
SUITABILITY OF THE
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SUITABILITY OF THE
INSTRUMENT
SUITABLE TO MEASURE THE FLOW OFTURBULENT STREAM
MEASURE THE DISCHARGE OF THETURBULENT STREAM ACCURATELY ASCOMPARED TO OTHER METHODS
NO SITE CONSTRUCTION IS REQUIRED
SINGLE PERSON OPERTATION
SELECTION OF DISCHARGE
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SELECTION OF DISCHARGE
MEASUREMENTSECTION &
POURING POSITION Discharge measurement section should be
turbulent with no stagnant pools (water
velocity less than 0.1 m/s). The measuringposition should be in moving but not fast
flowing water
The pouring position should be at least 25 times
the width of stream at discharge measurement
section and the flow should be highly turbulent
for better mixing of salt solution.
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DETERMINATION OF QUANTITY
OF SALT Measure the Av. Width and Av. Depth of
the discharge measurement section and
multiply the two together.
Select the quantity of salt to use from the
Table.
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Table
Width (m) X
Depth (m)
Back Ground Conductivity
0-100 s 100-500 s 500-2000 s< 0.1 250 g 500 g 750 g
0.1 to 1.0 500 g 750 g 1000 g
> 1.0 1000 g 1500 g 1500 g
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Procedure for Discharge measurement
1. Choose a turbulent section for pouring salt solution2. Choose a measuring position. Check that the conductivity probe can be
submerged in the water without air bubbles being trapped by theprobe
3. Switch on the Flow stream
4. Find out background conductivity
5. Find out salt quantity and add to water in a bucket6. Pour the solution slowly in the stream but within 15 seconds.
7. Measure conductivity at measuring position
8. When test is completed get
Mass of salt
Elapsed time Background conductivity
Peak conductivity
Discharge in l/s.
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L 25 B>
POURING POSITION
MEASURING POSITION
FLOW
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GEOLOGICAL INVESTIGATIONS -
HYDROPOWER PROJECTS
STABILITY OF WEIRS
The foundation mass should be impermeable (non-jointed,
non-fractured and thoroughly crystalline igneous rocks,
claystones, massive sandstones and massive limestones) toavoid leakage.
Narrow river valley is suited most for construction of weir
Stable hillslopes attribute to the long life and stability of the
reservoir.
Sites should be selected carefully so as to be free from
defects which could result to leakage from reservoirs
Leakage may threat the safety and stability of the weir/dam.
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GEOLOGICAL STRUCTURES
Bed: A sedimentary layer whose thickness is more than acentimeter.
Dip: The maximum angle of inclination of a bed with the
horizontal.
Fault: A fracture along which it shows evidence of
relative movements.
Fold: Bends or curvature or undulations developed in the
rocks of the earths crust as a result of stresses to which
these rocks have been subjected from time to time.
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DEFECTIVE FEATURES
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SITE SELECTION
INTAKE
Should be at narrow valley. Bends should be avoided.
Banks should be stable.
No land slides.
Minimum turbulence in flow.
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DIVERSION WEIR AND INTAKE SITE
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DESILTING TANK AND CHANNEL
Flatter land.
Free from cross drainages.
No active slide zone.
Slopes should be stable.
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FOREBAY AND SPILLWAY
Flatter land.
Filling of land should be avoided.
Slopes should be stable. Natural stream should be nearby for spill water.
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PENSTOCK
Alignment should be along the ridge. Shortest length.
Minimum bends.
POWER HOUSE
Easy accessibility.
Flatter ground.
Above high flood level.
Stable slope.
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