Presentation by Kun Yan, Deltares, and Sanne Muis, VU University Amsterdam, at the Data Science Symposium, during Delft Software Days - Edition 2019. Thursday, 14 November 2019, Delft.

1. Climate Change
C3S_422_Lot2_Deltares - European Services
– Deltares in association with JBA, DMI, CNR-ISMAR, UCC MaREI
Kun Yan and Sanne Muis
15 Nov 2019
Understanding impact of extreme sea levels under climate change

2. Climate
Change
C l i m a t e i m p a c t o n c o a s t a l a r e a s
Netherlands under 2m Sea
Level Rise
Increased intensity and frequency of tropical cyclones
Higher storm surge, more floods, more barrier closure
Higher waves, changes in
wave direction, more
coastline erosion

3. Climate
Change
N o t a l w a y s b a d n e w s
Renewable energy production
Wind farm operation & Maintenance
Harbour & Port:
SLR and increased high tide allow larger container ship
Wind, Tide, Storm Surge, Sea Level, Currents, Waves
Need for a consistent coastal dataset reveal changes under
climate impact!!!

4. Climate
Change • New ERA 5 reanalysis data available, needs for new sea level reanalysis
• Needs for data based on climate scenarios with global/regional climate models (CMIP5)
• Needs for good practice and demonstration of climate information applied in coastal sectors
• Opportunity for commercial applications and services
T o w a r d s a n e w g l o b a l d a t a s e t
Wind velocity magnitude for the HIRHAM5 regional dataset (left) and combination with the
background EC-EARTH model for the same timestamp (right) Source: DMI
Global temperature in ERA5, source: Climate Data Store

5. Climate
Change
C 3 S S e c t o r a l d e m o n s t r a t i o n
C3S program brings the opportunity
We provide:
• Two Pan-European dataset: hydro and wave
• Five User Cases
• Dataset ingested to the CDS

6. Climate
Change
M o d e l l i n g
Model grid of GTSM in Southeast Asia and Europe
Domain and bathymetry of the ECMWF WAM model
WAM model:
• 0.1 x 0.1 degree (11 km x 11 km)
• Wave parameters along 20m depth
line
GTSM:
• 2D barotropic model, unstructured global grid
• 25 km ocean - 2.5km coastal/1.25km EU coasts
• 45,000 output locations
• See presentation Xiaohui/Martin Verlaan
• Modelling tools
• Hydrodynamic: Deltares Global Tide and Surge Model
(GTSM)
• Wave: ECMWF WAM

7. Climate
Change
S c e n a r i o s a n d e p o c h s
GTSM model mean-sea level when forced with 2100 RSLR field for RCP8.5 (CMIP5)

8. Climate
Change
Z o o m i n t o u s e c a s e s
Flood risk:
Adriatic Sea (Italy)
Baltic Sea (Denmark)
Irish Sea (Ireland)
Atlantic Ocean (Ireland)
Industrial:
Offshore wind, Port operations (UK)
Coastal erosion:
North Sea (Netherlands)
Use cases in C3S_422 Lot2
Set Examples of good practice in the development of climate services for coastal users

9. Climate
Change
C o p e n h a g e n s t o r m s u r g e ( D M I )
Overview map of the Baltic Sea region (Madsen et al., 2019);
The designed dike to protect the city of Copenhagen. Black: existing dike,
red: projected dike, yellow: need for coastal defence (source: Politiken).

10. Climate
Change
C o p e n h a g e n s t o r m s u r g e ( D M I )
Climate change indicators for the Copenhagen use case for the RCP8.5 mid-century (2041 – 2070) and RCP 4.5
end-century (2071 – 2100) periods relative to present day (1977-2005). (Muis et al., 2020. under review)
Overview map of the Baltic Sea region (Madsen et al., 2019);
The designed dike to protect the city of Copenhagen. Black: existing dike,
red: projected dike, yellow: need for coastal defence (source: Politiken).

11. Climate
Change
O f f s h o r e W i n d E u r o p e ( J B A )
Changes
• Wind speed, Significant wave height
Impact
• Total available energy
• Operation and Maintenance (access, vessel, cost)
Results
• Generated Energy: 3% decrease in Europe (RCP8.5 2040-
2070), €1,000 million/year, 8 million tons CO2/year
Adaptation:
• Innovations in Turbine design/more turbines
• Innovations in maintenance strategies/vessels
Limitations:
• Offshore wind O&M not been widely considered
• Based on single GCM, subject to uncertainties
Locations used for O&M modelling in Europe (JBA)
Photo credits: JBA

12. Climate
Change
A v a i l a b l e o u t c o m e i n t h e C D S
• Hydro dataset European coast
• Hydro indicators European coast
• Wave dataset European coast
• Wave indicators European coast
• Use case: Offshore wind (EU)
• Use case: Ports (UK)
• Use case: Baltic Sea (Denmark)
• Use case: Mediterranean (Italy)
• Use case: Atlantic and Irish sea
(Ireland)
• Use case: North Sea (Netherlands)

13. Climate
Change Validation
• Comparison against GESLA tide gauges
• Good performance with mean bias of -10 cm
• No clear spatial pattern, although stronger
negative bias in areas prone to tropical cyclones
V a l i d a t i o n o f t h e 1 i n 1 0 - y e a r w a t e r l e v e l s
RP10 – ERA5 climate reanalysis (1979-2014)

14. Climate
Change
C h a n g e i n 1 i n 1 0 - y r w a t e r l e v e l
Water level (SLR + tide + surge), RCP8.5(2050) vs. HIST
Surge for RP10, RCP8.5(2050) vs. HIST
Water level (SLR + tide) for HAT,
RCP8.5(2050) vs. HIST

15. Climate
Change
• Changes in RP10 for RCP4.5 (2100) • Changes in RP10 for RCP4.5 (2100) minus
effects of SLR
C h a n g e s l a r g e l y d r i v e n b y s e a - l e v e l r i s e

16. Climate
Change
I m p r o v e m e n t s v e r s u s e x i s t i n g d a t a s e t
CoDEC dataset vs. existing datasets:
• High resolution at the coast (1.25km) and high-resolution climate forcing (0.25°)
• High resolution time-series along all coasts
• Nesting points included for regional to local-scale studies
• Non-linear interactions between SLR, tides and surges included
Comparison with GTSR dataset
• Muis et al, 2016, Nature Communications
– GTSMv2.0 vs GTSMv3.0
– ERA-Interim vs. ERA-5
• Performance is improve for 66% of the tide
gauge stations
• Mean absolute error reduced by 25%

17. Climate
Change • Better representation of tropical cyclones
• Maximum surge height for Irma increased from 0.8 tot 2.2
m (2.4 m was observed)
A d d e d v a l u e o f h i g h - r e s o l u t i o n c l i m a t e d a t a
Dullaart et al. Clim Dyn (2019).
https://doi.org/10.1007/s00382-
019-05044-0

18. Climate
Change
F u t u r e r e s e a r c h d i r e c t i o n s
• Explore additional links to the data and downscaling
– Regional/local studies to translate changes into morphological changes,
impact on ecology
– Socio-economic impacts, cultural heritage
• ERA5 will become available from 1950 onwards
– Longer record make it possible to improve extreme value statistics and
analyze climate variability
• Large uncertainty because of the use of a single climate model
– new GTSMip6 project will run the CMIP6 ensemble of IPCC climate
simulations

19. Climate
Change
G T S M - C M I P 6 : T o w a r d s I P C C A R - 6 ( 2 0 2 1 )
Objectives
• To develop future projections of TWL for the CMIP6 model ensemble (better physics, higher
resolution)
• To analyse differences historical vs. future differences and contributions
• To assess bias and spread in the model ensemble
Long term…
• To assess how coastal extremes and risks change
over time to inform policy-makers (AR6)
• To built a community that collaborates to jointly
develop future projections of extreme sea levels

20. Climate
Change • HighResMIP experiment (<50km, 1-3 hourly)
• Better representation of extremes
• Ensemble of 6 climate models
A p p r o a c h

21. Climate
Change International consortium:
• VU, Netherlands (Job Dullaart, Jeroen
Aerts)
• PIK, Germany (Matthias Mengel)
• UNESCO-IHE, Netherlands (Trang
Duong, Rosh Ranasinghe)
• USGS, USA (Li Erikson)
• KNMI, Netherlands (Rein Haarsma,
Dewi le Bars)
HPC in international clusters
• Cartesius (NL) with support from
SurfSARA (DECEI project)
• LRZ (DE)
• NASA (USA)
A p p r o a c h

22. Climate Change
Questions?
If you want to know more… get in touch!
Kun.yan@deltares.nl
Sanne.muis@vu.nl