Risk Management, Lecture 3
Stress test
Urban water logging and nuisance
JEAN-MARIE BUIJS
JASPER VAN DEN HEUVEL
IN THE NEWS
https://www.nu.nl/binnenland/6303017/zware-regenval-en-hoge-grondwaterstand-zorgen-voor-meer-stroomstoringen.html
AGENDA
• Stress test
• Urban water system
• Break
• Climate scenario’s and water nuisance
• Assignment
• Apply lessons learned and assignment to your project
DELTA PROGRAMME
By 2050, the lay-out of the Netherlands must be as climate-proof
and water-resilient as possible to accommodate water nuisance,
drought, heat, and (urban) flooding, while (re)developments must
not entail any additional risks of damage and fatalities insofar as this
is reasonably feasible.
To attain this goal, the Delta Decision sets out the interim target of
having climate-proof and water-resilient spatial planning
incorporated into the policies and actions of government
authorities: in regional and local spatial considerations, the
authorities will factor in the water resilience and climate proofing of
their own region.
DELTA PROGRAMME MOVIE
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APPROACH OF CLIMATE STRESS TEST
THE STEPS
What do we need to Analyse to estimate impact of climate effects?
• Probability of climate effects (now and in the future)
• Consequences. Which systems are affected, what is vulnerable?
(now and in the future?)
What are difficulties in considering Ambition?
• Awareness of e.g. politicians (availability of budget, capacity etc)
• To get all specialists at the table (e.g. impact on health care)
What are challenges considering Action?
• What are effective measures? Again: short term – long term
• Implement this in daily practice (e.g. how often do they replace
the pavement of a street?)
BACHELOR THESIS WAGENAAR
Stress test what is looks like
The city/area is split up in smaller areas to discuss along spatial
boundaries, or, the session is split over the 4 climate themes
Get together with experts on all fields, people from the
municipality, companies, the national government, the province
and other stakeholders as inhabitants
Use of data
Water nuisance with 70 mm of rain in 2 hours
Neighborhood typology
Stress test, the summary of Middelburg
Where to find information (check updates
version with new options like drawing)
Klimaateffectatlas: https://www.klimaateffectatlas.nl/en/
Climate scenario KNMI WH
Exactly what our future climate will look like is as yet uncertain. Based
on the global rise in temperature, KNMI has developed four climate
scenarios for the Netherlands. The G scenarios assume a global
temperature rise of 1°C by 2050, the W scenarios assume a rise of 2°C.
The GH and WH scenarios additionally assume a change in air flow
patterns, causing, e.g., summers to become drier.
The KNMI'23 scenarios are now available. You can read more about
these new scenarios on the KNMI website. Over the next few years, we
will work on developing new maps in the Climate Impact Atlas based
on the new KNMI'23 scenarios.
A map of water nuisance showing percentage paved surface
Get your information
The klimaateffectatlas provides a lot of information on the climate challenges, now and for the future in 2050.
Also information on the surfaces of green, grey and blue.
The basic website https://klimaatadaptatienederland.nl/ provides a lot of information on climate and adaptation.
The maps in the Climate Impact Atlas have been developed on the basis of national models. The results provide a
picture at the regional scale level; at the local level, the picture is usually approximate and indicative. At the
national level, the maps reflect the best data publicly available. The data scale level differs from one map layer to
the next. Maps featuring statistics, such as Number of tropical days or Precipitation shortage, reflect differences at
the national level. Other maps, such as the Heat map – perceived temperature, are more detailed.
For your assignment data by the climate impact atlas, learn page and public available data is sufficient. There is no
need to ask around for more detailed information. The assignment is about the right analysis and interpretation
of available data.
Other sources (check Learn page ‘Project’
Municipality Middelburg has a Waterplan document stating several facts like the type of sewer system and
groundwater facts. It is provided on Learn.
Vlissingen has a document on water management, also provided on Learn.
Another source for climate risk of urban infrastructure: https://resin-cities.eu/resources/risk-typology/
Risk Management, Lecture 3
Urban water logging and nuisance
JEAN-MARIE BUIJS
JASPER VAN DEN HEUVEL
OBJECTIVES
• Understand the basics of the urban water system
• Understand the relation between urbanization and urban water
logging and nuisance (probability)
• Understand the role of climate change for urban water logging and
nuisance (probability)
• Explain the impact of extreme precipitation in urban areas
(consequences)
• Apply above knowledge in the stress test for an urban area
2 MAART 2024
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AGENDA
• Stress test
• Urban water system
• Break
• Climate scenario’s and water nuisance
• Assignment
• Apply lessons learned and assignment to your project
URBAN DRAINAGE
Drainage systems are needed in urban areas because of
interactions between human activity and natural water cycle
Two main forms of interactions:
• Abstraction of water from the natural cycle to provide a water
supply for human life
• Covering of land with impermeable surfaces that divert rainwater
away from the local natural system of drainage
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
TYPES OF WATER
Two types of water that require drainage:
• Waste water: supplied to human life, maintain a standard of living,
satisfy needs of industry. Can cause pollution and health risk
• Storm water: precipitation that has fallen on built-up area. Can
cause inconvenience, damage, flooding, further health risks
(pollutants)
Figure 1.1 Interfaces with the public and the environment
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
URBAN DRAINAGE SYSTEMS
Evidence by studies on the relation between water and diseases
(Cholera), around 1850 point of departure for modern sewerage
UDS: aim to manage impact on human life and the environment
• Most urban areas: completely superficial system of sewers
• Some isolated or low-income communities: no drainage, no or locally
treated waste-water, storm water drained naturally
Public: low awareness appreciation (“flush and forget”).
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
EFFECTS OF URBANIZATION
https://ccrmediator.wordpress.com/2012/09/23/storm-water-run-off-disputes-resolving-neighbor-wars/
SUB SOIL
Also the sub soil is changed a lot due human activity
https://www.dinoloket.nl/
• Cross section (Ondergrondmodellen, BRO Geotop). You can
check for soiltypes/layers, depth etc)
• E.g. samples of the subsoil for specific locations
(Ondergrondgegevens, in Dutch)
Partially in English
https://www.dinoloket.nl/en
BRO GEOTOP CROSS SECTION
URBANIZATION RESULTS IN
•
•
•
•
•
Increase in amount of runoff in relation to infiltration
Greater peak flow on natural runoff and sewer systems
Greater risk of flooding
Implications for water quality (more pollutants)
Higher need for wastewater treatment
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
P3
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
AIMS IN RELATION TO STORM WATER
Traditional aim: to remove water from surfaces (especially roads) as
quickly as possibly: pipe system to nearest water course. Can cause
damage to the environment and risk elsewhere.
Modern aim: to remove rainwater for storms up to a particular severity
with the minimum of inconvenience to activities on the surface
Acceptance of rainstorm on movement of people and goods varies in
relation to ‘development’ (and dependency)
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
REASSESSMENTS
• Nowadays: nature of progress in relation to urban drainage systems
(UDS), its consequences, desirability and limits, more closely and
frequently reassessed
• UDS need to protect people and property from storm water, limit
impact on receiving water.
• For this reason, and to achieve other environmental and social
benefits, interest in more natural methods of disposing storm water is
increasing: Infiltration, storage, and vegetated systems
• To decrease the peak flow of runoff and increase the time to reach the
watercourse and sewer system
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
TYPES OF SYSTEMS
Sewerage: whole of centralized infrastructure system: pipes,
manholes, structures, pumping stations
Two types of conventional sewerage:
• Combined system: wastewater and storm water flow together in
the same pipe
• Separate system: wastewater and storm water in separate pipes
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
INTERNATIONAL PERSPECTIVE
Dataset: Wastewater
treatment (% population
connected)
Variable Total public sewerage (% of resident population connected to
urban wastewater collecting system = PUBTOTTR + PUBNOTR)
Unit Percentage
2000
Year
2010
2018
Country
Australia
..
93
93
Belgium
65
82
..
C hile
93
96
..
Denmark
100
90
92
France
..
82
81
Germany
..
96
..
85
87
..
75
..
71
..
98
99
100
98
100
..
75
..
..
Greece
Japan
Mexico
62
(E )
Netherlands
United Kingdom
(E )
United States
(E )
59
(E )
Data extracted on 18 Feb 2021 21:27 UTC (GMT) from OEC D.Stat
IN PRACTICE
High diversity of systems in the Netherlands, based on changing
perceptions about amongst others pollution of water:
Combined systems, improved combined systems, separated systems,
improved separated systems, Infiltration and transport (IT) sewerage,
wadi’s, store-and-settle basins (bergbezinkbassins), green buffers, water
squares, green roofs, et cetera.
Type of system has influence, just like the chance of a cloudburst in your
area, and the management and maintenance of the infrastructure
https://www.stowa.nl/sites/default/files/assets/PUBLICATIES/Publicaties%202019/STOWA%202019%2022%20WEB.pdf
DISCONNECTING
STOWA, 2019: ‘Afkoppelen: kans en risico’s van anders omgaan met hemelwater in de stad
‘Disconnnecting rainwater flows from the sewerage system’
https://www.stowa.nl/sites/default/files/assets/PUBLICATIES/Publicaties%202019/STOWA%202019%2022%20WEB.pdf
Levels of scale of water flows and potential solutions:
• Private space;
• Street level (public space, urban);
• Total water system (regional);
• Waste water streams.
Chapter 2: Possible measures to deal with water flows on private and public spaces and their
potential effects on the water system and waste water streams
Chapter 4: Among others street profiles with storage capacity; and disconnecting without
reducing the amount of paved area can increase water nuisance; Disconnecting requires a
different type of approach.
STOWA report
2019, p25
https://www.stowa.nl/sites/default/files/assets/PUBLICATIES/Publicaties%202019/STOWA%202019%2022%20WEB.pdf
SUDS
• Non-pipe systems / SUDS (sustainable urban drainage systems)
manage stormwater flows closer to the source to which they are
generated (decentralized)
• Using infiltration and storage properties of semi-natural features
• Can be combined with other aims (biodiversity, recreation)
• Take also potential disadvantages into account in design and
management (e.g. pollution by heavy metals)
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
RETENTION, STORAGE, DRAINAGE
Dutch policy since 2000
https://geografie.nl/artikel/water-op-het-schoolplein
SPONGE CITY CONCEPT
International literature on the ‘sponge city’- concept:
- The urban water cycle -> similar to natural cycle;
- With a lot of infiltration and minimal run off
- Water can be stored in the ground for usage in dry periods
https://www.stowa.nl/sites/default/files/assets/PUBLICATIES/Publicaties%202019/STOWA%202019%2022%20WEB.pdf
RESEARCH ABOUT FUNCTIONING,
MAINTENANCE AND PERCEPTIONS OF WADIS
URBAN DRAINAGE AS ENV. CHALLENGE
Environmental challenge, a need for:
• cost-effective and socially acceptable technical improvements in
existing systems
• assessment of the impact of those systems
• search for sustainable and resilient solutions
Partnership needed by policy makers, engineers, planners, builders,
environment specialists, together with all citizens
Butler, D., Digman, C. J., Makropoulos, C., & Davies, J. W. (2018). Urban drainage. Crc Press.
3 POINT APPROACH
Fratini, C. F., Geldof, G.
D., Kluck, J., &
Mikkelsen, P. S. (2012).
Three Points Approach
(3PA) for urban flood risk
management: A tool to
support climate change
adaptation through
transdisciplinarity and
multifunctionality. Urban
Water Journal, 9(5), 317331.
Figure 1. The Three Points Approach scheme. Both the axes are on a logarithmic scale. The horizontal axis represents the
flood return period and the vertical axis represents the magnitude of the rain event in terms of costs of maintenance
and damage of the urban infrastructure.
SYSTEMS AND PROFESSIONALS
Fratini, C. F., Geldof, G.
D., Kluck, J., &
Mikkelsen, P. S. (2012).
Three Points Approach
(3PA) for urban flood risk
management: A tool to
support climate change
adaptation through
transdisciplinarity and
multifunctionality. Urban
Water Journal, 9(5), 317331.
Figure 2. A conceptual description of the urban area as context of the decision making process in UFRM. This is just a
representation of the complexity characterising an urban context where the technical, social and natural systems
interact. However, the characteristics of the context change from project to project and from location to location.
WATER NUISANCE & FLOOD RISK
Water logging
and nuisance
Flood risk
BREAK
CLIMATE SCENARIOS
A climate scenario is a plausible representation of the future climate that
has been constructed for investigating the potential consequences of
human-induced climate change (IPCC)
• Climate impact atlas works today with the KNMI’14 Climate
Scenarios, which are also main input for the Delta Scenarios;
• Based on IPCC reports: Expected changes for 2050 and 2085 with
1981-2010 as reference;
• Extent of global temperature rise (moderate, warm) and change in
air circulation pattern (Low – High);
• KNMI (Dutch meteorological institute) new Climate Scenarios in 2023
More in depth insights: https://edepot.wur.nl/328690
KNMI‘14 climate scenarios for the Netherlands
CLIMATE IMPACT ATLAS:
WH SCENARIO FOR 2050
Exactly what our future climate will look
like is as yet uncertain. Based on the global
rise in temperature, KNMI has developed
four climate scenarios for the Netherlands.
The G scenarios assume a global
temperature rise of 1°C by 2050,
the W scenarios assume a rise of 2°C. The
GH and WH scenarios additionally assume
a change in air flow patterns, causing, e.g.,
summers to become drier.
Global temperature
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GLOBAL TEMPERATURE RISE
FUTURE CHANGES
IPCC: Changes in precipitation will not be uniform over the globe.
Contrast in precipitation between wet and dry regions, and between
wet and dry seasons, will generally increase
Dutch climate scenarios:
• Uncertainty about mean precipitation in summer
• In all scenarios, precipitation extremes increase throughout the year
• The change in precipitation extremes for a particular summer
scenario is quite uncertain. Also, rain showers are less dependent on
changes in air circulation, but more dependent on the processes
acting on the local scale.
• The probability for heavy rain showers increases in all scenarios,
albeit with a large uncertainty band.
2023 CLIMATE SCENARIOS
Available in Climate impact atlas after summer 2024 (some
sooner than others, e.g. groundwater level needed for
subsidence and foundation risks)
Reports and tools, several also available in English
https://www.knmi.nl/klimaatscenarios23-toolkit
https://www.youtube.com/watch?v=hthdPG8SX60
PRECIPATION RISKS
Short extreme events
• Cloudbursts
• Summer
• Local
Long periods with(out) rains
• Longer periods
• Winter
• Larger areas
UNKNOWN EXTREME EVENTS (LIMBURG 2021)
https://nltimes.nl/2022/01/24/limburg-flood-beyond-worst-case-scenario-report
PRECIPITATION  WATER NUISANCE
Watercourses
• Standards based on National Agreement Water (NBW
normen, Nationaal Bestuursakkoord Water)
• 1/100 year for built environment
• Ditches will overflow
• Both for short extreme events and long during
precipitation
Sewerage
• Standards for design
• Water not able to enter sewerage results in overflow
• Allowed to overflow 1 per 2 year (‘rainshower 8’)
Water on the streets
• Precipitation which cannot infiltrate directly or
runoff to surface water or sewerage
• Part of design
EXPECTED FOR 2050 HAPPENS NOWADAYS
Average of showers for
different periods of time:
+9,9 %
APPLIED TO URBAN AREAS
Short, extreme showers (cloudbursts) main risk, because of:
• High % paved surface (asphalt, pavement, roofs), low % green;
• Vulnerabilities (infrastructure, functions, facilities, housing, social)
which can result in high consequences
Statistics:
• Short events: varies between 10 minutes and 12 hours
• Cloudburst 1/500 year event, now a return time of 1/100 year event
• Including more hail and thunder
STRESSTEST STANDARDIZATION
First guide: Stresstest light
Based on public info to explore vulnerabilities and main issues
Standardized stress test: instructions for generic and applicable
components, to increase: Intercomparability and Quality of outcomes
Includes:
-
Starting points
Input data
Steps of information analysis
Method for model calculations
Display of results
Transmission of information
60
CLIMATE IMPACT ATLAS
Read: https://www.klimaateffectatlas.nl/en/how-to-use
4 Climate risks
Use the 2050 High Scenario (stress test = test for extreme events)
Map narratives for each climate risk
And basic maps: e.g. Neighborhood typology (usefull for area analyis)
https://www.klimaateffectatlas.nl/en/map-narratives
Results in first impressions
More detailed information needed based on local knowledge
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ASSIGNMENT CLIMATE IMPACT ATLAS
Go to:
https://www.klimaateffectatlas.nl/en/map-narratives
Waterlogging
Collaborate as Dutch and international team members (most
available in English, but e.g. not all info on maps)
Apply following tests and use the main Climate Impact Atlas to assess
urban flood risk for now and available 2050 scenario.
TYPOLOGY OF AREA
Go to: https://www.klimaateffectatlas.nl/en/map-narratives
• Check the map ‘Neighborhood typology’
• Zoom in to your area and check for the dominant typology and variety
within the area
• Use tools like maps.google / google earth and other relevant sources
to support the typology or provide additional insights with pictures
and/or maps
• Check with table Kleerekooper for urban flood risk of the type of area
FLOOD DEPTH
Check flood depth for your area for two extreme events
• 70mm/2 hours (1/100 years) and 140mm/2 hours (1/1000 years)
• What is the max. waterdepth in the area?
• Does it differ per event?
• Which locations are at risk for water nuisance in your area?
• Name the streets and add the (max) water depths
• The model on Climate impact atlas based on national scale: this can
be used as first indication (high uncertainty).
• Check if possible with other available information (website
municipality, local stress test, water plan)
DEVELOPMENT CHANCES
GROUND WATER NUISANCE
• Check the tab ‘Probability of excessive groundwater levels’ (only
scenario 2050 High)
• Compare the colored cells in your neighbourhoods with the range
of grey – small chance to red – very high chance of ground water
nuisance
COMPLETING WATER LOGGING
AND NUISANCE
Use available other sources in Climate Impact Atlas
• At least Water depth 70 mm/ 2hours and 140 mm / 2 hours
for now and 2050 high
Use other sources that provide insight in the local situation, like
height maps and water network (e.g. to consider runoff)
We will put on learn what we have available
MORE DETAILS (NOT MANDATORY)
More detailed underpinning and explanation for further studies
•
•
https://ruimtelijkeadaptatie.nl/publish/pages/156667/190131_notitie_standaarden_stresstest_wateroverlast.pdf
https://www.stowa.nl/sites/default/files/assets/PUBLICATIES/Publicaties%202019/STOWA%20201919%20neerslagstatistieken.pdf
Repetition times of 100, 250, 1000 years (100 + 1000 in Climate impact
atlas) for different stresses on system and different types of problems
Short (1 – 2 hours) and long (48h) to see effects on fast and slow
responding water systems, respectively urban and rural
7 standard events
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OPTIONS TO ASSES CONSEQUENCES (MANDATORY)
Waterdepth buildings (not in GIS built environment) characteristics:
• User function (vital infrastructure and vulnerable functions?)
• Basements, soutterain etc which can flood?
• Threshold water level ~15 cm (door, ventilation)
• Access to underground parking areas
• Critical and vital functions in basements or low levels
Infrastructure
• Also for roads and other infrastrucrture: check water depth and its
functions
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OTHER SOURCES (EU-LEVEL)
Another insight in climate change effects:
http://european-crt.org/map.html
(regional level: cities + surrounding areas)
EU satellite data
https://climate.copernicus.eu/
THIS WEEK AND NEXT WEEKS:
• Project lecture: Coaching meeting
• Conduct the Urban water logging and nuisance assessment
(pluvial flooding and water logging)
Next week
• Next lecture: Heat stress and drought
• Project lecture: Presentation area analysis + water nuisance
MAIN TYPES (NBW NORMS)
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EXPECTATIONS
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STANDARDS WATER NUISANCE
1/100 years for Built
environment (incl. urban areas)
Effort obligation and not a
result obligation for regional
water authorities
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