a whole of river basin approach to hydropower dam …€¦ · international organisations leading...
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A WHOLE OF RIVER BASIN APPROACH TO HYDROPOWER DAM
SAFETY12 November 2015
Rebecca Knott, Damwatch Engineering
Kelvin Berryman, GNS Science
New Zealand
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Contents
1. Introduction to Damwatch and GNS Science
2. What is Dam Safety
3. Why is it important
4. International Organisations Leading Dam Safety
5. Viet Nam – New Zealand Dam Safety Project
6. Whole of river basin Dam Safety Methodology:
outputs and benefits
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Introduction
• Damwatch and GNS - International consultants
• 30+ years working together on design and safety assessment
of new and existing dams
Dam engineering specialists
* design and rehabilitation
* dam safety & monitoring
* instrumentation
www.damwatch.co.nz
New Zealand’s leading provider of Earth, geoscience
and isotope research and consultancy services.
http://www.gns.cri.nz
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Introduction
Rebecca Knott
Principal Engineer, Manager Dam Safety Programme
Damwatch Engineering Ltd
Kelvin Berryman
Director, Natural Hazards Research Platform
GNS Science
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What is Dam Safety?
• The safe operation and management of dams and their reservoirs for
all stages of the dam’s lifecycle
From: initial planning,
investigation,
design,
construction,
commissioning,
assessment,
rehabilitation and
operation through to
decommissioning
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What is Dam Safety?
Necessary to protect :
people, property and the environment
from the potentially catastrophic impacts of a dam failure or unexpected
release from the impounded reservoir.
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Why should we focus on Dam Safety?
• Avoid these events !!!:
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Why should we focus on Dam Safety?
Loss of lives, loss of assets, loss of trust and reputation
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Dam Safety and Mekong River Commission aim:
“…the MRC aims to ensure that the
Mekong water is developed in the most
efficient manner that mutually benefits
all Member Countries and minimises
harmful effects on people and the
environment in the Lower Mekong
Basin.”
http://www.mrcmekong.org/about-mrc/
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Why should we focus on Dam Safety?
• Serious incidents and dam failure can occur at any time in a
dam’s lifetime
# of Incidents vs. Age All Dams
0
50
100
150
200
250
300
350
400
<6
11-1
5
21-2
5
31-3
5
41-4
5
51-5
5
61-6
5
71-7
5
81-8
5
91-9
5
>100
Age Range
# o
f In
cid
en
ts
Courtesy P Regan FERC
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International Organisations leading Dam Safety
International Commission on Large Dams (ICOLD)
International funders & NGO’s e.g. World Bank
Research Institutes and Universities
International Practice Leaders, e.g. USBR, USACoE, FERC
National Committees e.g. VNCOLD, ANCOLD,CDA, NZSOLD
Design Manuals, risk management procedures etc
Research publications Advances in practice
Good Practice Guidelines
National Practice
Technical Bulletins
Government Regulators
Laws, decrees, regulations
Policy and standards
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The Viet Nam-NZ Dam Safety
Project objective is to:
• reduce loss of life and economic
damage resulting from extreme
dam discharges
(i.e. dam spillway releases or dam
failure events)
The Viet Nam-NZ Dam Safety Project
Ba Ha Dam Discharge, 2009
Ia Krel 2 Dam Failure, 2013
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The Viet Nam-NZ Dam Safety Project
The V-NZ Dam Safety Project Phase 1 is being carried out over 2012 to 2015 with collaboration between
• New Zealand Partners (Damwatch and GNS):
Experience in management of cascade dam systems
Expertise in international dam safety regulations
Expertise in flood risk assessment
Expertise in seismic and landslide risks to dams
Expertise in renovation of existing dams
Successful history of dam safety
• Viet Nam Partners (MARD - WRU, VNCOLD, IGP)
Expertise in flood estimation
Expertise in flood modelling
Knowledge of Vietnamese dam safety regulations
Expertise in design of dams
Vietnamese agency for seismic hazard analysis
The funding partner is the New Zealand Government Aid Programme
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Viet Nam Dam Population
• Viet Nam has about 7,000 dams in total:
About 750 Large Dams
> 6,000 Small/Medium Dams
Reservoir Capacity (Mm3)
Dam
He
igh
t (m
)
Small Dams Medium Dams Large Dams
Dams of National Importance
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The project involves:
• Application of
internationally recognized
methods on a catchment-
wide basis to identify and
quantify risks to dams and
communities downstream
of the dams.
• INTEGRATED
APPROACH - unique
The Viet Nam-NZ Dam Safety Project Methodology
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• PLAY VIDEO
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Methodology
1. Quantify hazards
- Flood, Landslide, Earthquake
2. Assess dam fragility
- Spillway adequacy
- Dam stability
- Dam safety assessment
3. Quantify flooding
and impacts
- Inundation maps
- Consequence assessment
4. Evaluate improvements
- Dam upgrades
- CBRM improvements
VN-NZ Dam and Downstream Community Safety
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Dam Safety Project Pilot Catchment
– Hieu River Nghe An Province , Viet Nam
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VN-NZ Dam Safety - Seismic and Landslide Hazards
Seismic hazard relating to inter-plate slip
San Fernando dam, USA post Mw = 6.7 earthquake, 1971
Landslide dammed lake, New Zealand post Mw = 7.8 earthquake, 1929
Large landslides in upper catchment of Hieu River
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Impacts on dam safety from natural hazards
Need to understand the:
• occurrence,
• frequency, and
• magnitude
of external events that may impact on dam safety –
earthquakes – landslides - floods
BEST to do this BEFORE dam design and
construction begin
• Seismic analysis – regional – shared benefits?
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Good design investigation and hazard identification
Why is good design investigation important?
• Robust dam - get it right first time
• Avoid failure
• Avoid retrofit ($$) or compromised margins of safety
• Dam OK with natural hazards / external events
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Good design investigation
• International experience –
site investigations budget ~ 10% of total project costs
get the design right
• Challenge – getting the data for incorporation in design
(such as earthquake occurrence, frequency and
magnitude)
• Good investment in project risk management –
future dam safety reviews
reputational and political risk
social acceptance
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VN-NZ Dam Safety – Example Flood Hazard Outputs
Ban Mong Dam, Flood Hydrology
Flood Annual Reservoir Spillway Dam
Exceedance Inflow Outflow Freeboard
Probability
(1 in Y) (m3/s) (m3/s) (m)
1 in 50 4,890 4,847 2.3
1 in 200 6,273 6,126 2.2
1 in 1,000 7,871 6,964 0.3
1 in 5,000 9,486 8,566 Dam Overtopped
1 in 10,000 10,150 9,182 Dam Overtopped
PMF 12,460 10,872 Dam Overtopped
RESERVOIR INFLOW HYDROGRAPHS
DAM FAILURE HYDROGRAPHS
SCHEMATIC OF RESERVOIR FLOOD LEVELS
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VN-NZ Dam Safety Methodology – Example Outputs
Ban Mong Dam, Flood Inundation Maps (1 in 50 AEP Spillway Release)
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VN-NZ Dam Safety Methodology – Example Outputs
Ban Mong Dam, Flood Inundation Maps (Dam Failure Scenario)
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Ban Mong Dam, Consequence Assessment
GIS Layers:
What can it be used for?:
• Evacuation/response planning
• Building approvals
• Evacuation exercise planning
• Mitigation priorities
• Risk / impact analysis
• Basis for cost-benefit analysis
• Land-use planning
• Education / Information
VN-NZ Dam Safety – Consequence Identification
Consequence analysis tool that provides information about what could
happen to people, buildings, agricultural activities and infrastructure in a
natural hazard event / disaster
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Example - Identification of Potential Improvements
Examples of Dam Safety & CBDRM Recommendations after using DSM
Dam Safety Recommendation #1
Dam Safety Issue Risk of overtopping and failure of closure dam
in extreme flood events
Dam Upgrade Recommended Construct Parapet Wall on Closure Dam
Risk Reduction Achieved Significantly reduce risk of overtopping failure
of Closure Dam
Dam Safety Recommendation #2
Dam Safety Issue High risk of overtopping and failure of Closure
Dam during construction
Dam Upgrade Reccomended Improve flood passage during construction
Risk Reduction Achieved Reduce risk of dam failure during construction
CBDRM Improvement Recommendation #1
Dam Safety Issue No flood inundation maps for dam failure and
spillway release events
Dam Upgrade Reccomended Integrate DSM flood maps into emergency
response and evacuation planning
Risk Reduction Achieved Reduce impact of flood hazard on
downstream communities.
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VN-NZ Dam Safety Methodology Summary
Methodology:
• Delivers Evidence based Decision Making in Dam Safety for whole river basin
• Phase 1 Trialled successfully in Nghe An Province, Viet Nam
• 2016 – Phase 2 - Application of Tool in major river basin system – 1000km, 978 dams (905 small, 58 med, 15 large), 5 years – design complete, funding approval 95% ….
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Summary – Project Benefits
• DDCSI provides dam owners/managers an
understanding of:
• The potential risks related to their dams
• The natural hazards that can affect dams
• The reasons why dams fail, and
• Improvements that can be made to mitigate these risks
Phase 2 includes development of a prioritisation tool –
identify where investment is best spent to reduce risk
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Summary – Project Benefits
• River-basin approach to dam safety assessment:
• Comprehensive approach that considers both
upstream hazards and impacts on downstream
communities
• Provides solutions to improve dam safety and Disaster
Risk Management practices
• Provides tools for compliance with aspects of (most)
national regulations
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Using VN-NZ Dam Safety Methodology Outputs
Engineers and Planners can use outputs to design projects, such as:
Dam safety improvements
• Dam upgrade/structural improvements
• Dam operational improvements/flood peak mitigation options
• Multiple reservoir operation rules
• Early warning systems for dam operators and authorities
Community disaster risk management
• Improved downstream community resilience
• Early warning systems for communities
• Improved evacuation planning
Physical works
• Protective measure locations (e.g. dykes)
• Road and bridge improvements to improve evacuation routes and flow paths
• Infrastructure upgrades
Land use planning
• Identification of areas to restrict future development