Download Slide 1 - CIRCABC

Dam-break accidents and valley vulnerability. Risk
assessment and mitigation
ALQUEVA DAM EARLY WARNING SYSTEM
Natural events triggering
major accidents….
Maria Teresa VISEU, João PALMA ,
Carlos OLIVEIRA COSTA and Betâmio de ALMEIDA
Lisbon 1st October
Early Warning Systems (EWS)
Case study…
Monforte
!
Elvas
!
Estremoz
!
Borba
!
Vila Viçosa
!
Alandroal
!
Redondo
!
Évora
!
Reguengos !de Monsaraz
Mourão
!
Portel
!
Vidigueira
!
Cuba
!
Moura
!
Barrancos
!
Beja
!
Serpa
!
Aljustrel
!
Castro! Verde
Albufeira
Mértola
!
Rio Guadiana
Almodôvar
!
Alcoutim
!
Concelho
Alqueva Dam
Concrete arch dam
!
Sede de concelho
Castro! Marim
Vila Real de Santo
António
!
Tavira
!
Guadiana river basin
Internacional river (shared
with Spain)
Alentejo and Algarve
regions, south of Portugal
Alqueva Dam risk analysis
Dam characterization
Hazard magnitude
 Dam height: 96 m
 Reservoir volume: 4150 x 1000 m3
 Reservoir area: 250 km2 and lenght: 83 km
 Dam downstream river lenght: 150 km
 Pedrógão dam: 22 km downstream of
Alqueva dam
 Flood design: 10 000m3/s (controled
spillways)
 Multi-purpose structure for irrigation and
energy production
 Dam owner – EDIA (Empresa de
desenvolvimento e Infra-estruturas do
Alqueva SA)
Early Warning Systems (EWS)
General criteria
EWS must be site specific and depend on dam and
dam-break flood characteristics (hazard
identification) but specially on population and
flood prone area characteristics (vulnerability
assessment)
Alqueva dam EWS design obliged to undertake a
two step approach study:
• an overview over the strengths and weaknesses
of the EWS main solutions
 Public warning using audible systems
(sirens and loudspeakers)
 Personal direct
notification via
telephone or cell
phones also
including the
door-to-door
• the Alqueva dam risk analysis focused in the
characterization of the flood prone area
 Television or radio station news broadcasts
Alqueva Dam Risk analysis
Vulnerability characterization
Dam-break flood prone area
Dam-break flood simulation for the extreme
failure scenario (fast and complete failure)
defined three risk zones, according to the
level of danger:
 Red or ZAS zone (self rescue) - area swept
by the flood wave in t < 30 min
 Orange or ZIP zone - area swept by the
flood wave in 30 < t < 120 min
 Green or ZIS zone - area swept by the
flood wave in t > 120 min
Alqueva Dam risk mitigation
EWS in Alqueva ZAS zone
 81 persons living in ZAS zone in
14 scattered edifications located
along the river
!
!
 A growing use of water for
recreational purposes is taking
place in the flood prone area.
Therefore, a greater number of
people may occasionally be at
risk
!
!
!
Marmelar
!
!
!! !
!
!
!
!
!!
!
!!
!
!
!
! !
!
!
!
!
!
!
!
!
!!
!
!
!
!
! ! de Carvão
Vale
!
!!
!
!
! !
!
!
!
!
 EWS design goal: provide audible
notification to the general public
and personal notification to those
living in ZAS zone…
Alqueva
!
! !!!
!!
!
Moura
!
Pedrogão
!
!
!!
!
!
!
!
!
!
!
!!
!
!
!
! !
!
Mina da Orada
Machados
!
ALQUEVA DAM EARLY WARNING SYSTEM
General characteristics
 For people in ZAS flood prone
area, a public EWS composed by
11 warning units (outdoor sirens)
will be installed
 The dam main responsible
maintains a list of addresses
and phone numbers of
people living in the ZAS zone
 For the population with disabilities, living in
the ZAS zone, the personal notification
component can be used to assure
notification and assistance as necessary
(telephone calls and/or door-to-door
notification)
ALQUEVA DAM EARLY WARNING SYSTEM
General characteristics
 The 11 sirens are a component of a
larger system
P.O.C.
Supervision
PC
 An emergency operational centre
(POC) with supervision equipment
will be installed, having the
possibility to communicate
bidirectionaly with the sirens along
the ZAS
 The POC is able to send coded
messages to the sirens using the
UHF radio network or the GSM
network
UPS
PSTN
UHF radio
+
GSM (SMS)
11 warning
units
ALQUEVA DAM EARLY WARNING SYSTEM
General characteristics
Acknowledgments are due to EDIA for its
 The sirens are able to receive
messages, decode them and
execute the instructions (broadcast
a specific message)
support
 Each siren allows issuing both siren
wail patterns and programmed
voice messages
 The POC supervises the global
health of the system, and as soon
as it detects that a siren is out of
service, issues a message to dam
operation personnel
 Sirens can be triggered manually,
on dam site, by the dam main
responsible
I Thank you for your attention
Early Warning Systems (EWS) …How?
EWS can be generally divided into three types:
 Public warning using audible
systems (sirens and loudspeakers)
also including visible systems
(stobe lights and billboards)
 Personal direct notification via
telephone or cell phones also
including the door-to-door
notification
 Television or radio station news
broadcasts
There is no single warning system that can
completely meet the desired notification
requirements. Each EWS type has strengths and
weaknesses.
Public warning – Audible systems (sirens)
Strengths and Disadvantages
 Instant communication to all
affected people, enabling fast
alerting to highly populated
areas
 Good coverage, including
isolated areas
 High degree of credibility to
audience
 Low maintenance cost
 High cost of implementation
 Meaning of the siren wail may
be ignored or not recognized
 Warning posts may suffer
degradation due to vandalism
issues
Public warning – Mobile Loudspeakers
Personal notification - Door-to-door notification
Strengths and disadvantages
The advantages:
 Low cost
 High degree of credibility to
audience
 Can reach those with
disabilities (door-to door)
The weaknesses:
 Extremely time consuming
 Only limited information can be
delivered
 Only a limited area can be
notified quickly
 Risk of exposure to personnel
delivering message and use
equipment and personnel that
could be used more efficiently
elsewhere
Personal notification
Via automated telephone service
Advantages and Disadvantages
The advantages:
 Good coverage
 Fast and targeted notification
to those on the phone call list
 Good audio component (better
understanding of the purpose
of the warning)
 Not very high cost
The weaknesses:
 Only effective if people have
and is near a phone which is
turned on and not in use as well
as if the call is answered
 Not available during telephone
outages
 Direct dial only (hotels, offices
excluded)
 Problems serving large
populations
Destination list corresponding to a
geographical zone
Television or radio broadcast notification
Strengths and disadvantages
 Inexpensive
 Instant communication to all
affected people
 Gives detailed information and
can keep people up-to-date
 Wide coverage and generally
available as most people have
televisions
 Risk of a certain delay until
emission effectively begins
 Message control by authorities
is limited
 Only effective if televisions are
turned on and for people who
are inside their houses at the
time of emergency
 Not a selective broadcast
audience,
so
emergency
message will reach all people
receiving TV or radio signal
 Not available during power
outages