1.2. Reservoirs

8/13/2019 1.2. Reservoirs

1/48

Part B1: Basics

B1.2 Reservoirs


2/48

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)


3/48

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/


4/48

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


5/48

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


6/48

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)


7/48

B1.2.1ReservoirsWhy store: The anatomy of a reservoir


8/48

B1.2.2ReservoirsHow much to store

3 2

( ) ( )h f V f A


9/48

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


10/48

B1.2.2ReservoirsHow much to store: Mass curve


11/48

B1.2.3ReservoirsDam design: Forces on a dam

2

2

hF

2

hF W t

W

is the specific weight of water


12/48

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


13/48

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


14/48

B1.2.3ReservoirsDam design: Seepage: Typical flow nets


15/48

B1.2.3ReservoirsDam design: Seepage: Typical flow nets:

Earth dams


16/48

B1.2.3ReservoirsDam design: Seepage: Zoned earth

dams: piping


17/48

Toe drain

Blanket drain

Chimney and blanketdrain

Impermeable core andblanket

B1.2.3ReservoirsDam design: Seepage: Earth dams


18/48

B1.2.3ReservoirsDam design: Seepage: Earth dams:

Zoned

Filters

Core


19/48

B1.2.3ReservoirsDam design: Seepage: Zoned earth dams


20/48


Ramganga project


21/48


Kishan rockfill dam


22/48

B1.2.3ReservoirsDam design: Spillways: Types

Side channel

Chute

Shaft

Syphon

Ogee


23/48

B1.2.3ReservoirsDam design: Spillways: Side channel


24/48

B1.2.3ReservoirsDam design: Spillways: Chute spillways


25/48

B1.2.3ReservoirsDam design: Spillways: Shaft spillways


26/48

B1.2.3ReservoirsDam design: Spillways: Ogee spillways


27/48

B1.2.3ReservoirsDam design: Spillways: Ogee spillways


28/48

B1.2.3ReservoirsDam design: Spillways: Hydraulic jump

Hd

h1

h2

2

2

2

v

g

2

1

2

v

g

h

hL


29/48



30/48

V= Stream velocity (m s-1)

R = Hydraulic radius

S = Slope

n = Manning roughness


Manning's equation

2 3 1 2R SV

n


31/48

p = pressure (Pa)

r = Density (kg m-3)

g = Gravity (m s-2)

v = velocity (m s-1)

z= elevation (m)


Bernoulli's equation

2

constant2

p vz

g gr


32/48

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)


33/48


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


34/48

Hd

h1

h2

2

2

2

v

g

2

1

2

vg

h

hL


Sums: Height of the jump

1 22 2

1 1 1 12

2

2 4

h h v hh

g


35/48


Location of the hydraulic jump


36/48

B1.2.3ReservoirsDam design: Spillways: Encouraging a

jump


37/48

B1.2.4ReservoirsTechnical problems with dams: Silting


38/48

B1.2.4ReservoirsTechnical problems with dams: Silting


39/48

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


40/48

B1.2.4ReservoirsTechnical problems with dams: Failure: St

Francis breach


41/48

B1.2.4ReservoirsTechnical problems with dams: Failure: St

Francis breach


42/48

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


43/48


San Luis Dam Slide


44/48


Fatehgarh dam earthquake damage


45/48


46/48

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/


47/48

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


48/48

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

1.2. Reservoirs

Documents

Transcript of 1.2. Reservoirs