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Part B1: Basics
B1.2 Reservoirs
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B1.2 ReservoirsTopics
Why store?
Raise head, smooth flow, conflicts and trade offs
Determination of reservoir volume/height
Mass curve approach, simulation approach
Dam design
Forces on a dam, Types of dam, Seepage, Spillways
Technical problems with dams
Silting, failure
Social impact of dams
Seminars (Monday W6)
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B1.2 ReservoirsSeminars: Monday 17/1, 16:00
Go to www.dams.org
World commission on dams report overview (skim thisits pretty long and dull concentrate on thefindings)
Responses to the report Contrast donors (such as the ADB) with utilities (such as
the Indian Ministry of water resources) and dam-orientedorganisations (such as ICOLD or the ICE)
Case studies (2)
On the web (not necessarily on dams.org)
Find an example of a bad dam project
Find an example of a good dam project
We will be discussing
Who benefits and who loses when a dam is built?
Who makes the decisions?
What makes a dam good or bad?
http://www.dams.org/http://www.dams.org/ -
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B1.2 ReservoirsSeminar groups
Group 1 (16:00) Group 2 (16:30)
Gunjan Dhingra
Mike Farrow
Hannah Jones
Matt Knight
Paul Knowles
Peter Adams
Elizabeth Aldridge
Jonathan Bailey
Khesraw Bashir
Christopher Baxter
Richard Buckland
Dafydd Caffery
Samuel Carter
Nedim Dzananovic
Philip Hallgarth
Neil Harding
Martin Hill
Karen Hockey
Ching Hong
Adam Ithier
Peter Jordan
Jan Jozefowski
Rob Morford
Chris Swinburn
Kate Taylor
Celia Way
Marie Wells
Matt Whitley
Eral Kahveci
Imra Karimn
Martin Kendrick
Shua Lii
Beth Mcdowall
Adil Munir
Roger Palmer
Anthony Pearson
Gareth Pilmoor
Ann Ruthven
Matthew Scott
Ben Sheterline
Melanie Sim
Nicholas Thompson
Daniel Tkotsch
Christopher Tompkins
Ian Yeung
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B1.2.1ReservoirsWhy store
Raise head
Hydro power
Allow greater flow to irrigation
Smooth flow
Reliable Hydro power
Off season irrigation
Flood control
Domestic Water supply
Other reasons
Fishing
Leisure
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B1.2.1ReservoirsWhy store: Conflicts
Maximising head vs. Maximisingstorage If the storage is used, the head is reduced
Water use vs. flood control
Water use prefers a full reservoir (for uselater)
Flood control the reservoir should be empty
(so floodwater can fill it)
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B1.2.1ReservoirsWhy store: The anatomy of a reservoir
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B1.2.2ReservoirsHow much to store
3 2
( ) ( )h f V f A
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B1.2.2ReservoirsHow much to store
n in out Q Q Q
in stream precipitationQ Q Q
......out used spill evaporation leakage seapageQ Q Q Q Q Q
precipitationQ AP
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B1.2.2ReservoirsHow much to store: Mass curve
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B1.2.3ReservoirsDam design: Forces on a dam
2
2
hF
2
hF W t
W
is the specific weight of water
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B1.2.3ReservoirsDam design: Types of dam
Type Materials Typical crosssection
Plan view
Gravity Concrete, rubblemasonry
Arch Concrete
Buttress Concrete,ferrocement, timber,
steel
Embankment Earth, rock
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B1.2.3ReservoirsDam design: Seepage: Flow nets
Lines of constant potential, and constant flow
Perpendicular Should form a series of squares
Note boundary conditions
ES254 Geotechnics Lectures 8&9
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B1.2.3ReservoirsDam design: Seepage: Typical flow nets
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B1.2.3ReservoirsDam design: Seepage: Typical flow nets:
Earth dams
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B1.2.3ReservoirsDam design: Seepage: Zoned earth
dams: piping
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Toe drain
Blanket drain
Chimney and blanketdrain
Impermeable core andblanket
B1.2.3ReservoirsDam design: Seepage: Earth dams
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B1.2.3ReservoirsDam design: Seepage: Earth dams:
Zoned
Filters
Core
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B1.2.3ReservoirsDam design: Seepage: Zoned earth dams
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B1.2.3ReservoirsDam design: Seepage: Zoned earth dams
Ramganga project
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B1.2.3ReservoirsDam design: Seepage: Zoned earth dams
Kishan rockfill dam
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B1.2.3ReservoirsDam design: Spillways: Types
Side channel
Chute
Shaft
Syphon
Ogee
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B1.2.3ReservoirsDam design: Spillways: Side channel
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B1.2.3ReservoirsDam design: Spillways: Chute spillways
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B1.2.3ReservoirsDam design: Spillways: Shaft spillways
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B1.2.3ReservoirsDam design: Spillways: Ogee spillways
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B1.2.3ReservoirsDam design: Spillways: Ogee spillways
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B1.2.3ReservoirsDam design: Spillways: Hydraulic jump
Hd
h1
h2
2
2
2
v
g
2
1
2
v
g
h
hL
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B1.2.3ReservoirsDam design: Spillways: Hydraulic jump
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V= Stream velocity (m s-1)
R = Hydraulic radius
S = Slope
n = Manning roughness
B1.2.3ReservoirsDam design: Spillways: Hydraulic jump
Manning's equation
2 3 1 2R SV
n
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p = pressure (Pa)
r = Density (kg m-3)
g = Gravity (m s-2)
v = velocity (m s-1)
z= elevation (m)
B1.2.3ReservoirsDam design: Spillways: Hydraulic jump
Bernoulli's equation
2
constant2
p vz
g gr
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B1.2.3ReservoirsDam design: Spillways: Hydraulic jump:
Sums: Critical depth
E
h
2
2
vE h
g
crith
minE
Tranquil
Rapid
E = SpecificEnergy(m)
h = head (m)
g = Gravity
(m s-2
)
v = velocity
(m s-1)
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B1.2.3ReservoirsDam design: Spillways: Hydraulic jump:
Sums: Head loss
22
22
L d
vh H h h
g
Hd
h1
h2
2
2
2
v
g
2
1
2
vg
h
hL
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Hd
h1
h2
2
2
2
v
g
2
1
2
vg
h
hL
B1.2.3ReservoirsDam design: Spillways: Hydraulic jump:
Sums: Height of the jump
1 22 2
1 1 1 12
2
2 4
h h v hh
g
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B1.2.3ReservoirsDam design: Spillways: Hydraulic jump:
Location of the hydraulic jump
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B1.2.3ReservoirsDam design: Spillways: Encouraging a
jump
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B1.2.4ReservoirsTechnical problems with dams: Silting
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B1.2.4ReservoirsTechnical problems with dams: Silting
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B1.2.4ReservoirsTechnical problems with dams: Failure
modes Overtopping inadequate spillways (1/3)
Foundation failure (1/3)
Excess seepage through foundation
Piping insufficient drainage/grading
Wave action
Erosion of downstream face
Slump
Bank stability
Seismic activity
Degradation lack of maintenance
Material supplies sub specification
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B1.2.4ReservoirsTechnical problems with dams: Failure: St
Francis breach
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B1.2.4ReservoirsTechnical problems with dams: Failure: St
Francis breach
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B1.2.4ReservoirsTechnical problems with dams: Failure:
Piping - Hellhole dam
Dec 22 3:00 pm Dec 23 7:00 am
Dec 23 9:30 am Dec 23 3:30 pm
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B1.2.4ReservoirsTechnical problems with dams: Failure:
San Luis Dam Slide
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B1.2.4ReservoirsTechnical problems with dams: Failure:
Fatehgarh dam earthquake damage
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B1.2.5ReservoirsSocial impact of dams
Climate change
Fertility of downstream banks
Displacement Changes in local economy
Deforestation
Possibility of financial collapse
Possibility of failure
See; World commission on damswww.dams.org
http://www.dams.org/http://www.dams.org/ -
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B1.2 ReservoirsSummary
Storage needs may conflict
Mass balance and the mass curve are useful waysto size reservoirs
Seepage is an issue with earth dams but can bedealt with by zoning
There are several varieties of spillway, includingside channel, chute, shaft, syphon, and ogee
Hydraulic jump is a useful technique to reducespillwater levels
Dams can fail by silting, overtopping, foundationfailure wave action, erosion and lack ofmaintenance
Dams can have social and environmental impacts
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B1.3 Next..Water conveyance
http://localhost/var/www/apps/conversion/2003-04/lecture%20presentations/3.%20water%20conveyance.ppthttp://localhost/var/www/apps/conversion/2003-04/lecture%20presentations/3.%20water%20conveyance.ppt