ESTD19 – ASSIGNMENT 2
Climate Risk Assessment of Public Infrastructure Projects in the
INTRODUCTION: Context
Under the new Federal/Provincial/Territorial/Municipal Climate Resilient Infrastructure
Investment Program (CRIIP), municipalities are eligible to apply for funding to higher orders of
government to support public infrastructure projects. This program applies to projectsthat are
aimed at enhancing the climate resiliency of existing infrastructure through improvements via
enhanced operations and asset management plans, as well as building new infrastructure that
is designed to a higher climate change standard. The total program has $50 Billion in its budget
allocated over the next 10 years. New capital projects costing $10 million or more are eligible
for funding, with a $3 Billion maximum (total) for any single project. Funding will be shared
between Federal, Provincial/Territorial, and Municipal governments onan equal 1/3 -1/3-1/3
basis.
The National Federation of Municipalities has endorsed this program, and the Municipal
Councillors from the City of Metropolis are eager to tap into Federal and Provincial funding to
support much needed infrastructure improvements. The Provincial Governor is also onside, but
only if the infrastructure projects are both cost effective and provides an acceptable level of
climate protection over the life of the asset. There are also expectations to deliver projects on-
time and on-budget, while using infrastructure investment to kick-start the economy in the
Post-COVID-19 era.
The City of Metropolis has been adversely impacted by extreme weather events in the past,
which has damaged infrastructure and caused disruptions in essential services. Some key
infrastructure assets are also in need of major repairs and even replacement, so the CRIIP
represents a unique opportunity to upgrade essential services. It is also an area where climate
change is projected to be significant with corresponding implications for social, economic and
eco- systems, as soon as 2050 if not before. In response to this funding opportunity, the
Mayor of Metropolis has instructed the City Manager’s Office to review infrastructure
proposals currently on file and recommend which projects should be considered by City
Council for submission to CRIP by the end of the next Federal fiscal year (March 31st, 2023).
The City’s Environment and Planning Department has been tasked to present
recommendations for up to five key infrastructure projects to Metropolis City Council at their
next budget meeting in September, 2022.
ASSIGNMENT TASK: Approach and methods
As the subject matter expert on climate resiliency employed by the City of Metropolis, you have
been tasked by the City Manager and the Director of the Environment and Planning Office to
provide a report outlining your infrastructure recommendations. A previously prepared
background document (Appendix A: Backgrounder) developed by your team to help build the
case for climate resiliency, can be used to inform and populate your report.
As there is no universal criterion for making good climate-related decisions, and essentially no
“right” or “wrong” answers, you have decided that a “team” approach is needed that follows an
open and transparent process that invites a wide range of expertise and views. Furthermore,
based on an extensive literature scan, you have decided that two sources of information would
be helpful in guiding the report, and informing the recommendations. One is the standard
Climate risk assessment process, and the other is a hierarchy of simple, complicated and
complex risks and how these shape and inform decision making as outlined in the IPCC AR5.
The climate risk assessment process is a decision support tool, based on ISO 31000, adopted in
ICLEI’s BARc tool, and follows the PIEVC Protocol. The 5-step approach to climate proofing
(becoming more climate resilient) can be applied to different spatial scales, from the national,
to regional, municipal networks and systems, and individual infrastructure assets (Figure 1).
When done correctly, the steps outline a process to engage internal and external experts,
undertake a credible and transparent risk assessment, identify and select appropriate
adaptation measures, outline an implementation strategy and plan, and build upon existing
methods to monitor and report on progress. For each step, key questions that can guide the
risk management process are provided.
Figure 1: Climate Risk Management Process
Source: adapted from ISO 31000
Guiding questions for each step along the climate risk assessment process include:
1. Screening and Scoping: Project Definition
• How is the proposed project (elements or systems of interest) vulnerable to the impacts
of current and potential extreme climate events over its life span? What are the climate
parameters of most interest to the proposed project? Is there sufficient information
available to undertake an assessment? Who are the main stakeholders that should be
engaged in the assessment (those who are impacted, and those who are responsible for
taking action)? How does the natural environment/ecosystems act as an adaptation
measure against climate change?
2. Risk Assessment: Vulnerability, Severity, Probability and Adaptive Capacity
• What are the current and historical trends in climate? How is climate projected to
change in the future and in what ways? How will this affect infrastructure/human/eco-
systems of interest? What are the root causes for projected impacts (sensitivity,
adaptive capacity, exposure)? What reasonable assumption (quantitative and
qualitative) can be made about climate change, its impacts and risk?
3. Selection of Adaptation Measures: Identifying and Selecting Adaptation Measures
• What adaptation solutions are technically feasible to address the projected climate
vulnerabilities? How might measures be described as operational, maintenance and
asset management, or replacement by new design and construction? What are the costs
and benefits of these options throughout the asset lifecycle? What are the preferred
options in the context of the project?
4. Implementation: Implementation Plan
• How are adaptation solutions integrated into the project design? Who has the capacity
to implement the selected adaption option(s)? Are there additional key stakeholders
that need to be brought into the project? Is there a need for additional capacity building
or research?
5. Monitoring and reporting: Tracking Through Key Performance Indicators
• How can progress towards vulnerability reduction be measured? How can monitoring be
used for learning? How will lessons be collected, assimilated, and used to improve
future road/transit investment and energy generation/transmission projects? Which
existing monitoring systems can be built on? Which reporting needs should be
addressed?
While the risk management process is a powerful process to assess climate risk, decision
making can be challenging as understanding interactions between climate change (and extreme
weather), systems and assets being impacted, and identifying appropriate adaptation
responses can be a daunting task. Interactions and causal relationships can be simple and
linear, they can involve multiple elements and appear complicated, and in some cases the risks
can be complex where the decision-making process demands greater attention and deeper
depths of analysis. Figure 2 outlines the hierarchy of risk types differentiating between simple,
complicated and complex, along with their respective characteristics of decision making.
Decisions around climate resiliency and adaptation are often initially perceived to be simple,
yet upon further exploration their resolution ends up following a process where relationships
are complicated, if not complex. While not perfect, this hierarchy can be a useful tool to
describe decision making and outcomes when planning for climate resiliency.
Figure 2: Hierarchy of simple, complicated, and complex risks, showing how perceived risks
multiply and become less connected with calculated risk with increasing complexity. Source:
Figure 2.2, IPCC WGII AR5, Part A: Global and Sectoral Aspects, p. 202
THE EXERCISE
As the first stage in the development of a proposal, you and your team have decided to tackle
work that supports Steps 1-3 in Figure 1i. Drawing upon the background material, provide
answers to the following questions:
Step 1: Screening and scopingii
A. Identify the objective(s) of your project.
B. What are the primary infrastructure assets of interest? Identify key components and
subcomponents that are of interest.
C. What additional infrastructure and services are secondary interests?
D. What are the historic, current, and projected climate parameters of interest and concern? What
previous extreme weather events are most relevant to this assessment and why?
E. What are the critical load thresholds of selected key infrastructure components and
operational processes that cause undesired consequences when being exceeded?
F. What are the lifecycles or design life of your key infrastructure assets or their components?
G.Identify and explain which ecosystems should be considered, that interact with the project(s)?
H. What internal stakeholders need to be engaged (e.g. asset owners, operations, planning, design
and procurement, finance, safety and business continuity, and communications) in the risk
assessment process?
I. What external stakeholders need to be engaged (e.g. Government representatives, non-
governmental organizations, sectoral trade associations, climate services organizations or companies,
Conservation authorities, community-based groups, media, etc.) in the risk assessment process?
J. Summarize your key points in the table belowiii:
Table 1: Scoping summary
Asset/System
of interest
Infrastructure
components
and design
loads
Past extreme
weather
events
Climate
parameters
Stakeholder
Groups
(e.g. internal
and external)
Ecosystems of
interest
(e.g. Alpine,
forests,
agriculture,
aquatic, etc.)
Transportation
asset #1
Transportation
asset #2…
Energy asset #1
Energy asset
#2…
Additional asset
#1
Additional asset
#2…
Step 2: Risk Assessment
A. What are the probabilities of occurrence of the climate-related hazards for current climate
conditions? How are these projected to change, under the RCP4.5, and RCP 8.5?
B. What are the consequences of climate-related impacts on the infrastructure asset
components and their ability to deliver essential services? Are these critical to the overall
health of the population and the regional economy?
C. Identify possible cumulative effects where climate-related impacts can have cascading
consequences? Provide three examples where this could lead to undesirable outcomes.
D. What groups, sectors or areas of the City of Metropolis and the Karibu River Watershed are
especially vulnerable to extreme weather conditions and climate change impacts and should be
highlighted as areas of concern for today and for the foreseeable future?
E. What are the consequences and secondary impacts on the surrounding community? What
groups or sectors could be adversely affected and severely impacted?
F. How would you describe the biggest risk that you have identified, in terms of it being simple,
complicated, or complex?
G. Summarize your key points in the table below:
Table 2: High-level identification of climate hazards and climate-related impacts
Asset/System/Components
Hazards
Potential impacts
Secondary impacts
and potential
cumulative effects
Transportation asset #1
Transportation component
Energy asset #1
Energy component
Additional Asset
Asset component
The following tables might help trigger some ideas in formulating your answers.
Table 3: Climate-related impacts in transportation infrastructure
Transport
Hazards
Potential impacts
Road
More frequent and
intense storms
including freezing rain
events
Wetter winters and drier
summers
Higher temperatures
Increased sea level
Wildfires
Ongoing freeze/thaw cycles
Increased scour of bridges
Increased instability of embankments
Damage to road surfaces and foundations
Flooding of roads
Damage to bridges and tunnels
Traffic accidents
Increased pollution levels
Rail
More frequent and
intense storms
including freezing rain
events
Wetter winters and drier
summers
Higher temperatures
Increased sea level
Wildfires
Ongoing freeze/thaw cycles
Incursion into fleet vehicles
Flooding of rail lines, increased risk to train traffic
Increased scour of bridges
Increased instability of embankments
Increased switches and signal failures
Increased rail buckling
Ports
Sea level rise
Increased storminess and
storm surges
Higher winds
Flooding of equipment
Disruption to operations
Safety issues for navigation
Airports
Increased/more intense
precipitation
Higher temperatures
Flooding of runaway
Disruption to operations
Increased risk during landing and taking off
Lift of aircraft reduced (affecting fuel use and
take-off slots)
Table 4: Climate-related impacts in energy infrastructure
Energy
Hazards
Potential impacts
Fossil fuel and
nuclear generation
Increased rainfall intensity
Sea level rise
Shoreline erosion
Higher temperatures
Reduced summer rainfall
Flooding of fossil fuel and nuclear power plants,
decommissioned nuclear sites and nuclear waste
reprocessing and storage facilities
Reduced efficiency
Reduced available water for cooling
Renewable wind
energy
Increased rainfall intensity
Reduced wind
High wind gusts
Freezing rain
Reduced efficiency
Inoperable
Sufficient damage in need of repair
Renewable solar
panels
Increased rainfall intensity
High wind gusts
Freezing rain
Higher temperatures
Freeze/thaw cycles
Reduced efficiency
Inoperable
Sufficient damage in need of repair
Thermal expansion
Safety hazard
Electricity
transmission and
distribution
Higher temperatures
Increased/more intense
precipitation
Surface water, tidal and
fluvial flooding
High wind gusts
Ground subsidence
Freeze/thaw cycles
Overheating of transmission lines
Reduced capacity of network
Flood risk to substations
Damage to overhead power lines and ancillary
infrastructure
Reduced stability of foundations and tower
structures
Fuel processing and
storage
Sea level rise
Storm surges
Flood risk to fuel storage, transporting and
processing facilities
Environmental contamination
Step 3: Adaptation measures
A. Based on a high-level risk assessment, where should the team focus on reducing vulnerability and
risks, while increasing resiliency and adaptive capacity?
B. At a high-level, how would you describe where this would apply, and the likely implications of the
following adaptation optionsandor measures moving forward:
a) retreat from high-risk areas
b) hardening of infrastructure
c) greening of infrastructure
d) changes in operations and maintenance
e) asset lifecycle management plans
f) additional risk insurance
g)emergency management response and business continuity plans
f) communications and public engagement
g) other
4.0 MARKING SCHEME
Sections 1 and 2 represent the bulk of the report and are weighed equally (8 marks each). Section
3 is more exploratory and is worth less (4 marks). The total grade is 20.
Your answers will be marked according to the standard criteria associated with essay-type
responses, supported by evidence that you include from the data and narrative provided. In
addition, your grade will reflect whether:
The student has demonstrated his or her own thinking and analysis by integrating ideas or
examples from the course materials.
Information is presented in a clear, interesting, and dynamic way. Well written answers have
a logical progression of ideas and are supported by evidence.
The student uses correct grammar, spelling, and word choice in their written work.
Assignment 2: Appendix A
Background Report:
Setting the Scene for the Climate Risk
Assessment of the Millennium Bridge, the
Karibu Power Plant and Transmission
System, and the City of Metropolis
Source: adapted from Annex 1, Hodick, B., Becher, M, Schlonvoigt, A. and B. Heine (2019) Enhancing
Climate Services for Infrastructure Investments (CSI), Trainer Handbook (Eschborn, Germany: Deutsche
Gesellschaft fur, Internationale Zusammenarbeit (GIZ) GmbH), Draft. NOT FOR CIRCULATION.
1. Casestudysetting–TheKaribuRiverWatershedandthecityof
Metropolis
1.1. Environment
The Karibu River Watershed lies in the Eastern Province of South Country. The Northern parts
of the catchment are characterized by the high Upper Mountains, gently sloping south. The Upper
Mountains have been classified an Area of Extraordinary Beauty and they are a renowned
destination for ambitious hikers and climbers in summer, while winter tourism has been gaining
attention, especially alpine skiing. However, in the past years much of the forests had been
degraded due to rapid urbanization, wildfires, and uncontrolled land-use changes, including
conversion to productive agricultural land, especially along the foothills. An expansive wildfire
wiped out an estimated 20% of the forest cover a few years ago, and another 15% last year.
Glaciers that feed the rivers have also been retreating, more rapidly in recent years. The
snowpack accumulation during the winter season can have a significant impact on river flows
during the spring freshetteand thaw, especially if the winter season has experienced heavy
snowfall. Sudden convection rainfall events in late spring and early summer have also been
known to cause extensive flooding, especially if they combine with melt waters from glaciers and
snowpack. There is concern that loss of vegetative cover from successive years of wildfires will
exacerbate the level of risk to overland and riverine flooding. While most of the flooding in the
past has been watershed based (e.g. originating from the mountains in the north), there is
increasing concern over sea level rise and the potential for coastal flooding along low lying areas
in the south.
Currently, a new dam to provide hydropower is being built at the river midstream, to supplement
power that is provided by an aging Nuclear Power plant, just upstream. One tributary adds its
waters before the Karibu River reaches the major bridge that connects both parts of the city by
providing access for vehicles and public transit. Ferry service provides an alternative route across
the Karibu River, and there are plans to consider increasing Ferry capacity and frequency of
service. Another bridge further north is also under consideration that would likely function as a
toll road, while also providing a dedicated route for a proposed second transit corridor as part of
an expanded regional transit network. Planning is underway to identify the best location and
design requirements for a new transit hub, and rail storage and maintenance facility.
Electricityis supplied by one main transmission line that serves the city core first, including the
region’s hospital, with power lines crossing the Karibu River slightly upstream from the
Millennium Bridge to serve the city’s western suburb. Strong, steady winds comparable to
“Chinooks” are a common occurrence, that can also bring dramatic shifts in temperature,
especially during the winter season. Nonetheless the City and surrounding area has been known
for its widely variable precipitation, notably costly hail storms and occasional freezing rain
events/ice storms.
1.2. The City of Metropolis
Metropolis has about 6 Million inhabitants. It is a mega city in the Eastern Province, and an area
of major importance for economic activity and social life throughout the country. Metropolis is
equipped with residential and commercial/industrial areas, green spaces for recreation,
hospitals, schools and universities, as well as vast shopping facilities covering all needs. The City’s
University-affiliated Central Hospital is the regional hub for a broader health care network, and
provides core services for Cancer, Infectious Diseases, and other specialized health issues.
Thereby, the city is of major importance for the surrounding region, especially the smaller villages
and dwellings who benefit from the services and facilities offered by the city. There is also
extensive agriculture nearby, with many productive farms providing a reliable local food supply
to the residents of Metropolis, although most of the food produced oriented for an export
market. With a harbor and a waterfront along the Ocean, the city functions as a key gateway for
the trade of goods and commodities within the region. The main port also functions to receive
Cruise ships during the summer. The road leading across the bridge is of crucial importance for
traffic, transport and overall mobility, with Ferry service playing a secondary and supporting role.
The city is also an energy center for the region, with the existing Nuclear Power plant and the
hydro plant under construction having the combined capacity to provide electricity to a growing
population and economy to at least 2050, assuminga costly refurbishment of the main existing
facility and associated transmission infrastructure. A recent consultant’s report evaluating
potential energy generation alternatives has noted the suitability of the areas where the foothills
transition to the plains for supporting wind turbines. The viability of “wind farms” requires further
analysis, as initial reaction by the agricultural community is mixed, with some seeing this as an
additional source of revenue, while others see it as a scourge on an otherwise pristine rural
landscape. There are also opportunities for the expansion of Solar Panels, either as large scale
rural based systems, or integrated with urban infrastructure such as buildings and transportation
corridors.
1.3. The Greater Metropolis Region
The Greater Metropolis Region extends beyond the City of Metropolis and encompasses an area
of approximately 10,000 km2, that is larger than some of the countries Provinces. Two smaller
urban centres exist about 50 kilometres east and west of Metropolis, each with about 100,000
population. To the northwest is the Town of Trumanville which in recent years hasbeen
attracting individuals, couples, and families with young children, who are fleeing the high housing
costs and congestion of Metropolis, while seeking more affordable housing, larger properties,
and a quieter lifestyle. The Town of Trumanville has a newly established University and is also the
home of many IT start ups. In contrast the Town of Pleasantville is located to the northeast of
Metropolis, has an older population, and a declining industrial base where traditional
manufacturing jobs have been moving offshore. Pleasantville has housing prices that are more
affordable than those found in the City of Metropolis, and offers many amenities sought after by
retirees.
Figure 1: The City of Metropolis and the Karibu River Watershed
2. InfrastructuresinFocus:TheMillenniumBridgeandtheKaribu
Electricity System
2.1. The Millennium Bridge
The Millennium Bridge has been rebuilt, after the last bridge was severely damaged during a so-
called centennial flood in 1998 and had to be taken down due to safety reasons. During that
event, people and authorities noticed that early-warning and contingency plans were not
functioning properly, leading to severe human and economic losses.
Outline of socio-economic consequences due to the bridge failure
The socio-economic impacts of this event were severe, beyond the costs of the new bridge.
During the reconstruction phase, the river crossing of people and smaller vehicles was provided
by a ferry service relatively nearby, but larger vehicles had to do a long detour of approx. 80 km
to a larger ferry further north, eventually leading to losses for fresh or frozen products.
Commuting pupils and students from the Western banks had to leave their school buses at one
side of the river, take the ferry and then climb on the next bus at the other side. The education
statistics show a decrease in the final exam grades of commuting pupils. The health statistics of
this time show a significant increase in pulmonary diseases among schoolchildren, especially in
elementary school. Medical services had to operate by helicopter if there was an emergency
case at the Western banks of Karibu River. Longer travel times of every day commuters from
their apartments on the one side of the river to their offices on theother side of the river has
caused reduced performance of companies limiting their annual turnover. The intra-regional as
well as the inter-regional trade suffered from additional costs for transport as well as from a
loss of customers and goods due to vast delays in service delivery. In the second year of
reconstruction, the local traditional market, as well as several restaurants at the river banks that
represent important tourism places, had to be closed as theexpected number of tourists had
dramatically fallen the year before causing a dramatic decrease of number of overnight stays
and has only recovered since a few years. Buses have traditionally used the Millennium Bridge
to cross the Karibu River, and since 2010 a LRT route has operated as well. Transit stations are
located on both banks and act as significant mobility hubs. Transit ridership has been increasing
steadily over the past decade, and is projected to double by 2030 as additional service is added.
The new bridge spanning Karibu River was built after the disastrous flood in 1998, with the official
opening occurring in 2000. As a result the bridge was dubbed the Millennium Bridge. Financing
the new bridge was shared by the city administration of Metropolis and the Eastern Province.
The bridge was built in adherence to the existing building codes, with some minor consideration
of climate change. In 2001, it was nominated for the prize “Innovative infrastructure of the year”
by the National Engineering Society of South State. The technical details include (bridge
components illustration courtesy of Alberta Transportation):
Engineering specifies of the bridge
Infrastructure components
Design loads
Road surface
(asphalt cement pavement)
Design temperatures: Superpave Performance Grading (PG) 64-22
(highest temperature of asphalt increased from 50°C to 60°C)
Design life = 15 years
Bridge deck
Carbon fiber reinforced concrete; design life 75 years
Drainage system designed to the historical 50-year storm
Signage capable of withstanding wind gusts up to 90 km/hr
Bridge soffit at least 1 m above the historical 50-year flood
Guard rails ungalvanized and subject to salt caused deterioration
Expansion joints
Designed up to 35 ̊C and a temperature range of 60°C
Piers and abutments
Abutments designed to resist scouring of historical 100-
year peak flow(equivalent to 4,500 m3/s), but Piers are
designed to a lower standard
Clearance of bridge deck
above high-water level
Designed for historical 100-year storm, 68 mm/2 h, and the century
flood (for a design flood of 6.5m above sea level = +4.5m above
average) caused by downstream flows and runoff from Alpine
snowpack
Figure 2: Conceptual cross-section of the Millennium Bridge
The Millennium Bridge is managed by the Metropolis City Infrastructure Authority in cooperation
with the Province’s Road Maintenance Department. The bridge will be examined concerning
functionality and maintenance in a thorough check-up in the Spring of 2023. In this process,
possible repairs or refurbishments can be programmed by taking into account climate change
risks. Currently the bridge barely meets 3 of 4 Canadian Highway Bridge Design Code standards,
but with climate change another 2 standards will likely be exceeded within 30 years.
2.2 Karibu Power Plants and Ancillary Infrastructure
The Karibu Power plant was constructed in the 1970s and experienced power disruptionscaused
by extreme weather events, including flood damage to the Transmission Substation in 1998. In
addition to flooding, the region has experienced several severe wind-storms, two ice storms in
20 years, four prolonged heat waves and droughts during the past decade, and its first recorded
tornado (F1) last year. The new Hydro dam will add generation capacity but provide limited
benefit for flood control during extreme precipitation events. Transmission Towers are under
construction that will provide the suburbs along the Western Banks of the Karibu River with a
redundant power supply from the new Hydro dam.
Outline of socio-economic consequences due to power disruptions
The socio-economic impacts caused by extreme weather events have been variable. Lower water levels
during periods of drought have coincided with water temperatures rising more than 5 ̊C above normal.
This loss of cooling efficiency above 30 ̊C has resulted in a 5% reduction in electricity generation for every
1 degree increase in temperature, at a time when hotter (air) temperatures have increased the demand
for air conditioning. Increased water flows and embankment erosion has accompanied two flood events,
in 1998 during the centennial flood and a comparable flood in 2013. The centennial flood caused major
damage to the Transmission Towers, crippled a Transmission Step-Up Transformer, and wiped out the
Utility Poles that cross the KaribuRiver, knocking out power to the Western Banks. As a result of climate
proofing of the Transmission Step-Up Transformer and Transmission Towers there was limited damage
to this ancillary infrastructure during the flood of 2013, but it is believed that they may not hold up to
larger storms, especially Transmission and Distribution Lines that are vulnerable to freezing rain
events/ice storms. Further, a F1 tornado last year knocked down Power Lines supported by the
Transmission Towers, took out some of the Utility Poles, and severely damaged the Transmission Step-
Down Transformer. The F1 tornado resulted in a widespread blackout across Metropolis, and also made
the LRT line inoperative. In 1998 the Utility Poles were replaced to the existing design standard and were
wiped out again in 2013. Plans to upgrade them to withstand a future (climate change projection to
2050) 100-year storm and flood is under review, that may be incorporated into their asset lifecycle
management plans. Fortunately, the Hospital had installed a back-up power generator after the
centennial flood that allowed the facility to provide limited health services for 48 hours during and after
the 2013 flood. There are expectations however that the Hospital must be able to function normally
during extended power outages in the future, and additional back-up power may be needed. There are
plans to provide backup power to the LRT route, with lithium batteries the preferred option over natural
gas.
Engineering specificities of the Energy system
Components
Design loads
Generating station
Design life = 100 years
Design temperatures for water cooling max. 30°C
Sustained flood protection against 90 mm in 2h rainfall and 4,500m3/s
river discharge in the basin
Step-up transformers
Design life = 75 years
Sustained flood protection against 90 mm in 2h rainfall and 4,500m3/s
river discharge in the basin
Transmission lines & towers
Designed for wind speeds max. 120 km/hr
Deign life = 75 years
Sustained flood protection up to 90 mm in 2h rainfall and 4,500m3/s river
discharge in the basin
Susceptible to ice accretion from freezing rain >25 mm
Step down transformer
Design life = 50 years
Sustained flood protection against 70 mm in 2h rainfall and 3,000m3/s
river discharge in the basin
Sub-transmission to customer
Sustained flood protection against 70 mm in 2h rainfall and 3,000 m3/s
river discharge in the basin
Utility Poles
Design life = 35 years
Sustained flood protection against 58 mm in 2 h rainfall and 2,500 m3/s
river discharge in the basin
Susceptible to high wind gusts > 90 km/h
Susceptible to ice accretion from freezing rain >12.5 mm
The Karibu Power Plants and Transmission System is managed by the Metropolis Hydro Utility
Authority in cooperation with the Province’s Ministry of Energy. The electricity Distribution
system is operated and maintained entirely by the local hydro authority. The integrity and
resiliency of the Transmission and Distribution System will be examined on a regular basis,
while the Power plant is scheduled for a major refurbishment after the Hydro Dam is up and
running. More renewables from solar and wind may also be incorporated into the energy system
in the future. Enhancement of the existing Transmission and Distribution system is planned over
time, dependent upon the availability of funds for operations and asset lifecycle management.
3. ClimateInformation
3.1. Current climate and hydrology
The following graph shows the current climate conditions in the catchment on a monthly basis
for precipitation and on a daily basis for temperature.
The recent climate for Metropolis, South State & the Karibu River Hydrology
Month
Average Monthly
Precipitation
[mm]
Average Daily
Temperature
[° C]
The Karibu’s River flow is determined by the
precipitation patterns in the catchment – in
normal years: rainfall is fairly evenly
distributed, with more snow than rain falling as
precipitation during the winter. However,
during warm winters more precipitation has
been falling as rain, rather than as snow. During
the summer months there has been a shift
towards more intense convection storm events,
along with prolonged periods of drought.
The normal level of the river is at 2m (measure
point: +1.5m above sea level), with a mean
annual discharge pf 250m3/s. The highest
recorded water level was 8.43m, the highest
recorded discharge 4,500m3/s (1998 and
2013).
Besides the natural pastures at the Eastern &
Western Bank there are no flood
control/defence mechanisms in place. Intensive
agriculture may actually exacerbate run-off into
the Karibu River watershed, increasing riverine
flood risk towards the mouth of the river, and
extending inland to the Millennium Bridge and
beyond. Increased agricultural run-off is also
leading to lower water quality conditions, and
contributing increasing amounts of silt in the
bay. As a result there is growing concern over
decreasing draught at the Port, for both cargo
and passenger vessels.
Jan
95
1
Feb
80
2
Mar
110
6
Apr
145
12
May
120
17
Jun
120
23
Jul
125
26
Aug
110
24
Sep
90
20
Oct
100
14
Nov
110
8
Dec
105
3
Annual
mean
1310 mm
13.0°C
(Mean climate normal parameters 1981-2010)
3.2. Recent observed changes in climate and hydrology
The observed changes in annual mean temperature are +1.0°C since 1970. The lower parts of the
Karibu River catchment regularly experience high water levels from April through May, due to
the spring freshette. Overall, the frequency of strong rainfall events has increased. Although, the
average amount of annual rainfall is largely unchanged, especially during El-Niño events, more
intense convection storms have been experienced in the past decade, especially during the
summer. The bridge had been partly damaged by flooding in the past, however, the last severe
damage before the one leading to the reconstruction in 1998 had been before the beginning of
the 20th century (this information had to be looked up at the town’s archives). Thus, the flood in
1998 was called a centennial flood. However, the frequency of such disruptive high-water levels
appears to be increasing and a severe flood – similar to the one in 1998 – has reoccurred once
since.
A relatively new feature are random thunderstorms accompanied by strong rains in the northern
part of the watershed, where steep, bare rock slopes are common, leading to rapidly created
high-water levels, and eventually causing flooding of the cities original flood plain, that is now
urbanized. This includes embankment erosion near the Nuclear Plant that has been increasing.
The river basin where Metropolis is located is also slowly subsiding, which acts to amplify the
effects of sea level rise and storm surges. The other extremes experienced in recent years have
mainly occurred during La-Niña events, where precipitation has decreased accompanied by
drought conditions and heat waves, as wellas higher water temperatures about 5 ̊C warmer than
normal.
3.3. Climate projections in the Karibu River Watershed, based on
RCP4.5
Climate projections in the Karibu River Watershed, based on RCP4.5
Projections are to 2050 unless otherwise stated
Climate Variable
Probability of impact thresholds being exceeded
Temperature
Annual mean temperature rising by 2-3°C in the Upper Mountains and 1-3°C
in the river valley by the 2050s (compared to the 1970 to 2000 average).
By the 2080s annual mean temperature rising by at least 3°C in the Upper
Mountains and 2-4°C in the river valley
Increase in heat waves in summer and during La-Nina years with
o Very Likely occurrence of temperatures exceeding 35 ̊C in three
consecutive days.
o Likelyoccurrenceoftemperatureexceeding40 ̊Cononedayormore
leading to asphalt temperatures exceeding 64°C.
o Very Likely that the number of days >30°C will double by 2050, and
triple by 2080
• Warmer winters projected
o About as likely as not occurrence of extremely cold temperatures <-
20 ̊C.
Precipitation
Slight increase in mean annual precipitation by the 2050s (>5% compared to
the 1970 to 2000 average), and higher by the 2080 (>15%).
More intense precipitation in the late spring thru summer season and more
intense El-Nino related rains.
Overall slightly higher precipitation increase in the spring and summer than
the fall and winter.
Precipitation focused on shorter periods, with prolonged periods of drought.
Likely increase in thunderstorms with high intensity rainfall events in summer
(heavy rains over 70 mm/2-hr considered to be a 1-50 year event)
Very likely occurrence of freezing rain events, where ice accretion along the LRT
overhead catenary system and the Distribution lines/Utility polescould exceed
design standards of 12.5 mm.
Wind and storms
Likely Increase in extreme wind events with increased average and topwind
speed with sustained winds >90 km/hr and high wind gusts >120 km/hr.
Very Unlikely occurrence of F1 Tornadoes.
About as likely or not increase in the frequency and/or intensity of Typhoons.
Surface hydrology
More variable river flows likely.
Likely more frequent floods exceeding discharge of 4,300m3/s and exceeding
6.5m water level above sea level.
Longer periods without significant precipitation (dry spell).
Lower late summer river flows.
Very likely occurrence of variable water temperatures above 30 deg C. in the
Karibu River more than 5 days.
About as likely as not increase in the erosion of sloping land and reservoir
catchments.
Likely larger sediment loads occurring in the lower Karibu River.
Sea-level
Very likely sea-level increases of 30-50 cm by the year 2050, 50-70 cm by the
year 2080
Storm surges are likely to occur and are expected to have severe impacts
inland, depending upon elevation.
3.4. Climate projections in the Karibu River Watershed, based on
RCP8.5
Projections are to 2050 unless otherwise stated
Climate Variable
Probability of impact thresholds being exceeded
Temperature
Annual mean temperature rising by 3-4°C in the Upper Mountains and 2-4°C
in the river valley by the 2050s (compared to the 1970 to 2000 average);
By the 2080s annual mean temperature rising by at least 4-5°C in the Upper
Mountains and 4-6°C in the river valley
Increase in heat waves in summer and during La-Nina years with
o Virtually certain occurrence of temperatures exceeding 35 ̊C in three
consecutive days.
o Very likely occurrence of temperature exceeding 40 ̊C in one day or
more leading to asphalt temperatures exceeding 64°C.
o Virtually certain that the number of days >30°C will double by 2050,
and quadruple by 2080
• Warmer winters projected
o Unlikelyoccurrenceofextremelycoldtemperatures<-20 ̊C.
Precipitation
Slight increase in mean annual precipitation by the 2050s (15% compared to
the 1970 to 2000 average), and higher by the 2080 (>25%).
More intense precipitation in the late spring thru summer season and more
intense El-Nino related rains.
Overall higher precipitation increase in the spring and summer than the fall
and winter.
Precipitation occurring shorter periods, with prolonged periods of drought.
Virtually certain increase in thunderstorms with high intensity rainfall events
in summer (short and heavy rains with up to 60 mm/2 h).
Virtually certain increase in freezing rain events, where ice accretion along the
LRT overhead catenary system and the Distribution lines/Utility polescould
exceed design standards of 12.5 mm.
Wind and storms
Vitually certain increase in extreme wind events with increased average and
top wind speed with sustained winds >90 km/hr and high wind gusts >120
km/hr.
Unlikely occurrence of F1 Tornadoes.
Likely increase in the frequency and/or intensity of Typhoons.
Surface hydrology
More variable river flows very likely.
Very likely more frequent floods exceeding discharge of 4,500m3/s and
exceeding 6.5m water level above sea level.
Longer periods without significant precipitation (dry spell).
Lower late summer river flows.
Virtually certain occurrence of variable water temperatures above 30 deg C. in
the Karibu River.
Likely increase in the erosion of sloping land and reservoir catchments.
Very likely larger sediment loads occurring in the low Karibu River
Sea-level
Very likely sea-level increases of 40-70 cm by the year 2050, 80 cm – 1 m by the
year 2080
Storm surges are very likely to occur and are expected to have severe impacts
inland, depending upon elevation.
3.5. Climate projections in the Karibu River Watershed
(Pleasantville and Metropolis weather stations) for 2-hr
rainfall for 3 storm events, based on RCP4.5 and RCP8.5
Total
PPT
Pleasantville
T(years)
Historical
2030
2050
2080
GEV
RCP4.5
RCP8.5
RCP4.5
RCP8.5
RCP4.5
RCP8.5
25
56
58
59
61
62
62
66
50
66
67
68
70
73
71
76
100
76
77
78
79
82
81
88
Metropolis
T(years)
Historical
2030
2050
2080
GEV
RCP4.5
RCP8.5
RCP4.5
RCP8.5
RCP4.5
RCP8.5
25
54
55
56
59
60
60
63
50
61
63
64
66
69
67
71
100
68
69
70
71
74
72
79
3.6. Further uncertainty in projections for the 2-hr, 1-100 year
storm event in Pleasantville and Metropolis: low, 25%
quartile, median, 75% quartile, and high, for the RCP8.5
70.49
81.42
88.08
96.12
118.18
low
Q1
Median
Q3
high
67.11
73.13
79.23
89.3
113.56
low
Q1
Median
Q3
high
Appendix B: IPCC Likelihood Scale
Term
Likelihood of the Outcome
Virtually Certain
99-100% probability
Very Likely
90-100% probability
Likely
66-100% probability
About as likely as not
33 to 66% probability
Unlikely
0-33% probability
Very unlikely
0-10% probability
Exceptionally unlikely
0-1% probability
